5871944e61459cca9cbd9fa85a992186b838c691
[pandora-kernel.git] / drivers / usb / host / ehci-sched.c
1 /*
2  * Copyright (c) 2001-2004 by David Brownell
3  * Copyright (c) 2003 Michal Sojka, for high-speed iso transfers
4  * 
5  * This program is free software; you can redistribute it and/or modify it
6  * under the terms of the GNU General Public License as published by the
7  * Free Software Foundation; either version 2 of the License, or (at your
8  * option) any later version.
9  *
10  * This program is distributed in the hope that it will be useful, but
11  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
12  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
13  * for more details.
14  *
15  * You should have received a copy of the GNU General Public License
16  * along with this program; if not, write to the Free Software Foundation,
17  * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
18  */
19
20 /* this file is part of ehci-hcd.c */
21
22 /*-------------------------------------------------------------------------*/
23
24 /*
25  * EHCI scheduled transaction support:  interrupt, iso, split iso
26  * These are called "periodic" transactions in the EHCI spec.
27  *
28  * Note that for interrupt transfers, the QH/QTD manipulation is shared
29  * with the "asynchronous" transaction support (control/bulk transfers).
30  * The only real difference is in how interrupt transfers are scheduled.
31  *
32  * For ISO, we make an "iso_stream" head to serve the same role as a QH.
33  * It keeps track of every ITD (or SITD) that's linked, and holds enough
34  * pre-calculated schedule data to make appending to the queue be quick.
35  */
36
37 static int ehci_get_frame (struct usb_hcd *hcd);
38
39 /*-------------------------------------------------------------------------*/
40
41 /*
42  * periodic_next_shadow - return "next" pointer on shadow list
43  * @periodic: host pointer to qh/itd/sitd
44  * @tag: hardware tag for type of this record
45  */
46 static union ehci_shadow *
47 periodic_next_shadow (union ehci_shadow *periodic, __le32 tag)
48 {
49         switch (tag) {
50         case Q_TYPE_QH:
51                 return &periodic->qh->qh_next;
52         case Q_TYPE_FSTN:
53                 return &periodic->fstn->fstn_next;
54         case Q_TYPE_ITD:
55                 return &periodic->itd->itd_next;
56         // case Q_TYPE_SITD:
57         default:
58                 return &periodic->sitd->sitd_next;
59         }
60 }
61
62 /* caller must hold ehci->lock */
63 static void periodic_unlink (struct ehci_hcd *ehci, unsigned frame, void *ptr)
64 {
65         union ehci_shadow       *prev_p = &ehci->pshadow [frame];
66         __le32                  *hw_p = &ehci->periodic [frame];
67         union ehci_shadow       here = *prev_p;
68
69         /* find predecessor of "ptr"; hw and shadow lists are in sync */
70         while (here.ptr && here.ptr != ptr) {
71                 prev_p = periodic_next_shadow (prev_p, Q_NEXT_TYPE (*hw_p));
72                 hw_p = here.hw_next;
73                 here = *prev_p;
74         }
75         /* an interrupt entry (at list end) could have been shared */
76         if (!here.ptr)
77                 return;
78
79         /* update shadow and hardware lists ... the old "next" pointers
80          * from ptr may still be in use, the caller updates them.
81          */
82         *prev_p = *periodic_next_shadow (&here, Q_NEXT_TYPE (*hw_p));
83         *hw_p = *here.hw_next;
84 }
85
86 /* how many of the uframe's 125 usecs are allocated? */
87 static unsigned short
88 periodic_usecs (struct ehci_hcd *ehci, unsigned frame, unsigned uframe)
89 {
90         __le32                  *hw_p = &ehci->periodic [frame];
91         union ehci_shadow       *q = &ehci->pshadow [frame];
92         unsigned                usecs = 0;
93
94         while (q->ptr) {
95                 switch (Q_NEXT_TYPE (*hw_p)) {
96                 case Q_TYPE_QH:
97                         /* is it in the S-mask? */
98                         if (q->qh->hw_info2 & cpu_to_le32 (1 << uframe))
99                                 usecs += q->qh->usecs;
100                         /* ... or C-mask? */
101                         if (q->qh->hw_info2 & cpu_to_le32 (1 << (8 + uframe)))
102                                 usecs += q->qh->c_usecs;
103                         hw_p = &q->qh->hw_next;
104                         q = &q->qh->qh_next;
105                         break;
106                 // case Q_TYPE_FSTN:
107                 default:
108                         /* for "save place" FSTNs, count the relevant INTR
109                          * bandwidth from the previous frame
110                          */
111                         if (q->fstn->hw_prev != EHCI_LIST_END) {
112                                 ehci_dbg (ehci, "ignoring FSTN cost ...\n");
113                         }
114                         hw_p = &q->fstn->hw_next;
115                         q = &q->fstn->fstn_next;
116                         break;
117                 case Q_TYPE_ITD:
118                         usecs += q->itd->usecs [uframe];
119                         hw_p = &q->itd->hw_next;
120                         q = &q->itd->itd_next;
121                         break;
122                 case Q_TYPE_SITD:
123                         /* is it in the S-mask?  (count SPLIT, DATA) */
124                         if (q->sitd->hw_uframe & cpu_to_le32 (1 << uframe)) {
125                                 if (q->sitd->hw_fullspeed_ep &
126                                                 __constant_cpu_to_le32 (1<<31))
127                                         usecs += q->sitd->stream->usecs;
128                                 else    /* worst case for OUT start-split */
129                                         usecs += HS_USECS_ISO (188);
130                         }
131
132                         /* ... C-mask?  (count CSPLIT, DATA) */
133                         if (q->sitd->hw_uframe &
134                                         cpu_to_le32 (1 << (8 + uframe))) {
135                                 /* worst case for IN complete-split */
136                                 usecs += q->sitd->stream->c_usecs;
137                         }
138
139                         hw_p = &q->sitd->hw_next;
140                         q = &q->sitd->sitd_next;
141                         break;
142                 }
143         }
144 #ifdef  DEBUG
145         if (usecs > 100)
146                 ehci_err (ehci, "uframe %d sched overrun: %d usecs\n",
147                         frame * 8 + uframe, usecs);
148 #endif
149         return usecs;
150 }
151
152 /*-------------------------------------------------------------------------*/
153
154 static int same_tt (struct usb_device *dev1, struct usb_device *dev2)
155 {
156         if (!dev1->tt || !dev2->tt)
157                 return 0;
158         if (dev1->tt != dev2->tt)
159                 return 0;
160         if (dev1->tt->multi)
161                 return dev1->ttport == dev2->ttport;
162         else
163                 return 1;
164 }
165
166 /* return true iff the device's transaction translator is available
167  * for a periodic transfer starting at the specified frame, using
168  * all the uframes in the mask.
169  */
170 static int tt_no_collision (
171         struct ehci_hcd         *ehci,
172         unsigned                period,
173         struct usb_device       *dev,
174         unsigned                frame,
175         u32                     uf_mask
176 )
177 {
178         if (period == 0)        /* error */
179                 return 0;
180
181         /* note bandwidth wastage:  split never follows csplit
182          * (different dev or endpoint) until the next uframe.
183          * calling convention doesn't make that distinction.
184          */
185         for (; frame < ehci->periodic_size; frame += period) {
186                 union ehci_shadow       here;
187                 __le32                  type;
188
189                 here = ehci->pshadow [frame];
190                 type = Q_NEXT_TYPE (ehci->periodic [frame]);
191                 while (here.ptr) {
192                         switch (type) {
193                         case Q_TYPE_ITD:
194                                 type = Q_NEXT_TYPE (here.itd->hw_next);
195                                 here = here.itd->itd_next;
196                                 continue;
197                         case Q_TYPE_QH:
198                                 if (same_tt (dev, here.qh->dev)) {
199                                         u32             mask;
200
201                                         mask = le32_to_cpu (here.qh->hw_info2);
202                                         /* "knows" no gap is needed */
203                                         mask |= mask >> 8;
204                                         if (mask & uf_mask)
205                                                 break;
206                                 }
207                                 type = Q_NEXT_TYPE (here.qh->hw_next);
208                                 here = here.qh->qh_next;
209                                 continue;
210                         case Q_TYPE_SITD:
211                                 if (same_tt (dev, here.sitd->urb->dev)) {
212                                         u16             mask;
213
214                                         mask = le32_to_cpu (here.sitd
215                                                                 ->hw_uframe);
216                                         /* FIXME assumes no gap for IN! */
217                                         mask |= mask >> 8;
218                                         if (mask & uf_mask)
219                                                 break;
220                                 }
221                                 type = Q_NEXT_TYPE (here.sitd->hw_next);
222                                 here = here.sitd->sitd_next;
223                                 continue;
224                         // case Q_TYPE_FSTN:
225                         default:
226                                 ehci_dbg (ehci,
227                                         "periodic frame %d bogus type %d\n",
228                                         frame, type);
229                         }
230
231                         /* collision or error */
232                         return 0;
233                 }
234         }
235
236         /* no collision */
237         return 1;
238 }
239
240 /*-------------------------------------------------------------------------*/
241
242 static int enable_periodic (struct ehci_hcd *ehci)
243 {
244         u32     cmd;
245         int     status;
246
247         /* did clearing PSE did take effect yet?
248          * takes effect only at frame boundaries...
249          */
250         status = handshake (&ehci->regs->status, STS_PSS, 0, 9 * 125);
251         if (status != 0) {
252                 ehci_to_hcd(ehci)->state = HC_STATE_HALT;
253                 return status;
254         }
255
256         cmd = readl (&ehci->regs->command) | CMD_PSE;
257         writel (cmd, &ehci->regs->command);
258         /* posted write ... PSS happens later */
259         ehci_to_hcd(ehci)->state = HC_STATE_RUNNING;
260
261         /* make sure ehci_work scans these */
262         ehci->next_uframe = readl (&ehci->regs->frame_index)
263                                 % (ehci->periodic_size << 3);
264         return 0;
265 }
266
267 static int disable_periodic (struct ehci_hcd *ehci)
268 {
269         u32     cmd;
270         int     status;
271
272         /* did setting PSE not take effect yet?
273          * takes effect only at frame boundaries...
274          */
275         status = handshake (&ehci->regs->status, STS_PSS, STS_PSS, 9 * 125);
276         if (status != 0) {
277                 ehci_to_hcd(ehci)->state = HC_STATE_HALT;
278                 return status;
279         }
280
281         cmd = readl (&ehci->regs->command) & ~CMD_PSE;
282         writel (cmd, &ehci->regs->command);
283         /* posted write ... */
284
285         ehci->next_uframe = -1;
286         return 0;
287 }
288
289 /*-------------------------------------------------------------------------*/
290
291 /* periodic schedule slots have iso tds (normal or split) first, then a
292  * sparse tree for active interrupt transfers.
293  *
294  * this just links in a qh; caller guarantees uframe masks are set right.
295  * no FSTN support (yet; ehci 0.96+)
296  */
297 static int qh_link_periodic (struct ehci_hcd *ehci, struct ehci_qh *qh)
298 {
299         unsigned        i;
300         unsigned        period = qh->period;
301
302         dev_dbg (&qh->dev->dev,
303                 "link qh%d-%04x/%p start %d [%d/%d us]\n",
304                 period, le32_to_cpup (&qh->hw_info2) & (QH_CMASK | QH_SMASK),
305                 qh, qh->start, qh->usecs, qh->c_usecs);
306
307         /* high bandwidth, or otherwise every microframe */
308         if (period == 0)
309                 period = 1;
310
311         for (i = qh->start; i < ehci->periodic_size; i += period) {
312                 union ehci_shadow       *prev = &ehci->pshadow [i];
313                 __le32                  *hw_p = &ehci->periodic [i];
314                 union ehci_shadow       here = *prev;
315                 __le32                  type = 0;
316
317                 /* skip the iso nodes at list head */
318                 while (here.ptr) {
319                         type = Q_NEXT_TYPE (*hw_p);
320                         if (type == Q_TYPE_QH)
321                                 break;
322                         prev = periodic_next_shadow (prev, type);
323                         hw_p = &here.qh->hw_next;
324                         here = *prev;
325                 }
326
327                 /* sorting each branch by period (slow-->fast)
328                  * enables sharing interior tree nodes
329                  */
330                 while (here.ptr && qh != here.qh) {
331                         if (qh->period > here.qh->period)
332                                 break;
333                         prev = &here.qh->qh_next;
334                         hw_p = &here.qh->hw_next;
335                         here = *prev;
336                 }
337                 /* link in this qh, unless some earlier pass did that */
338                 if (qh != here.qh) {
339                         qh->qh_next = here;
340                         if (here.qh)
341                                 qh->hw_next = *hw_p;
342                         wmb ();
343                         prev->qh = qh;
344                         *hw_p = QH_NEXT (qh->qh_dma);
345                 }
346         }
347         qh->qh_state = QH_STATE_LINKED;
348         qh_get (qh);
349
350         /* update per-qh bandwidth for usbfs */
351         ehci_to_hcd(ehci)->self.bandwidth_allocated += qh->period
352                 ? ((qh->usecs + qh->c_usecs) / qh->period)
353                 : (qh->usecs * 8);
354
355         /* maybe enable periodic schedule processing */
356         if (!ehci->periodic_sched++)
357                 return enable_periodic (ehci);
358
359         return 0;
360 }
361
362 static void qh_unlink_periodic (struct ehci_hcd *ehci, struct ehci_qh *qh)
363 {
364         unsigned        i;
365         unsigned        period;
366
367         // FIXME:
368         // IF this isn't high speed
369         //   and this qh is active in the current uframe
370         //   (and overlay token SplitXstate is false?)
371         // THEN
372         //   qh->hw_info1 |= __constant_cpu_to_le32 (1 << 7 /* "ignore" */);
373
374         /* high bandwidth, or otherwise part of every microframe */
375         if ((period = qh->period) == 0)
376                 period = 1;
377
378         for (i = qh->start; i < ehci->periodic_size; i += period)
379                 periodic_unlink (ehci, i, qh);
380
381         /* update per-qh bandwidth for usbfs */
382         ehci_to_hcd(ehci)->self.bandwidth_allocated -= qh->period
383                 ? ((qh->usecs + qh->c_usecs) / qh->period)
384                 : (qh->usecs * 8);
385
386         dev_dbg (&qh->dev->dev,
387                 "unlink qh%d-%04x/%p start %d [%d/%d us]\n",
388                 qh->period,
389                 le32_to_cpup (&qh->hw_info2) & (QH_CMASK | QH_SMASK),
390                 qh, qh->start, qh->usecs, qh->c_usecs);
391
392         /* qh->qh_next still "live" to HC */
393         qh->qh_state = QH_STATE_UNLINK;
394         qh->qh_next.ptr = NULL;
395         qh_put (qh);
396
397         /* maybe turn off periodic schedule */
398         ehci->periodic_sched--;
399         if (!ehci->periodic_sched)
400                 (void) disable_periodic (ehci);
401 }
402
403 static void intr_deschedule (struct ehci_hcd *ehci, struct ehci_qh *qh)
404 {
405         unsigned        wait;
406
407         qh_unlink_periodic (ehci, qh);
408
409         /* simple/paranoid:  always delay, expecting the HC needs to read
410          * qh->hw_next or finish a writeback after SPLIT/CSPLIT ... and
411          * expect khubd to clean up after any CSPLITs we won't issue.
412          * active high speed queues may need bigger delays...
413          */
414         if (list_empty (&qh->qtd_list)
415                         || (__constant_cpu_to_le32 (QH_CMASK)
416                                         & qh->hw_info2) != 0)
417                 wait = 2;
418         else
419                 wait = 55;      /* worst case: 3 * 1024 */
420
421         udelay (wait);
422         qh->qh_state = QH_STATE_IDLE;
423         qh->hw_next = EHCI_LIST_END;
424         wmb ();
425 }
426
427 /*-------------------------------------------------------------------------*/
428
429 static int check_period (
430         struct ehci_hcd *ehci, 
431         unsigned        frame,
432         unsigned        uframe,
433         unsigned        period,
434         unsigned        usecs
435 ) {
436         int             claimed;
437
438         /* complete split running into next frame?
439          * given FSTN support, we could sometimes check...
440          */
441         if (uframe >= 8)
442                 return 0;
443
444         /*
445          * 80% periodic == 100 usec/uframe available
446          * convert "usecs we need" to "max already claimed" 
447          */
448         usecs = 100 - usecs;
449
450         /* we "know" 2 and 4 uframe intervals were rejected; so
451          * for period 0, check _every_ microframe in the schedule.
452          */
453         if (unlikely (period == 0)) {
454                 do {
455                         for (uframe = 0; uframe < 7; uframe++) {
456                                 claimed = periodic_usecs (ehci, frame, uframe);
457                                 if (claimed > usecs)
458                                         return 0;
459                         }
460                 } while ((frame += 1) < ehci->periodic_size);
461
462         /* just check the specified uframe, at that period */
463         } else {
464                 do {
465                         claimed = periodic_usecs (ehci, frame, uframe);
466                         if (claimed > usecs)
467                                 return 0;
468                 } while ((frame += period) < ehci->periodic_size);
469         }
470
471         // success!
472         return 1;
473 }
474
475 static int check_intr_schedule (
476         struct ehci_hcd         *ehci, 
477         unsigned                frame,
478         unsigned                uframe,
479         const struct ehci_qh    *qh,
480         __le32                  *c_maskp
481 )
482 {
483         int             retval = -ENOSPC;
484         u8              mask;
485
486         if (qh->c_usecs && uframe >= 6)         /* FSTN territory? */
487                 goto done;
488
489         if (!check_period (ehci, frame, uframe, qh->period, qh->usecs))
490                 goto done;
491         if (!qh->c_usecs) {
492                 retval = 0;
493                 *c_maskp = 0;
494                 goto done;
495         }
496
497         /* Make sure this tt's buffer is also available for CSPLITs.
498          * We pessimize a bit; probably the typical full speed case
499          * doesn't need the second CSPLIT.
500          * 
501          * NOTE:  both SPLIT and CSPLIT could be checked in just
502          * one smart pass...
503          */
504         mask = 0x03 << (uframe + qh->gap_uf);
505         *c_maskp = cpu_to_le32 (mask << 8);
506
507         mask |= 1 << uframe;
508         if (tt_no_collision (ehci, qh->period, qh->dev, frame, mask)) {
509                 if (!check_period (ehci, frame, uframe + qh->gap_uf + 1,
510                                         qh->period, qh->c_usecs))
511                         goto done;
512                 if (!check_period (ehci, frame, uframe + qh->gap_uf,
513                                         qh->period, qh->c_usecs))
514                         goto done;
515                 retval = 0;
516         }
517 done:
518         return retval;
519 }
520
521 /* "first fit" scheduling policy used the first time through,
522  * or when the previous schedule slot can't be re-used.
523  */
524 static int qh_schedule (struct ehci_hcd *ehci, struct ehci_qh *qh)
525 {
526         int             status;
527         unsigned        uframe;
528         __le32          c_mask;
529         unsigned        frame;          /* 0..(qh->period - 1), or NO_FRAME */
530
531         qh_refresh(ehci, qh);
532         qh->hw_next = EHCI_LIST_END;
533         frame = qh->start;
534
535         /* reuse the previous schedule slots, if we can */
536         if (frame < qh->period) {
537                 uframe = ffs (le32_to_cpup (&qh->hw_info2) & QH_SMASK);
538                 status = check_intr_schedule (ehci, frame, --uframe,
539                                 qh, &c_mask);
540         } else {
541                 uframe = 0;
542                 c_mask = 0;
543                 status = -ENOSPC;
544         }
545
546         /* else scan the schedule to find a group of slots such that all
547          * uframes have enough periodic bandwidth available.
548          */
549         if (status) {
550                 /* "normal" case, uframing flexible except with splits */
551                 if (qh->period) {
552                         frame = qh->period - 1;
553                         do {
554                                 for (uframe = 0; uframe < 8; uframe++) {
555                                         status = check_intr_schedule (ehci,
556                                                         frame, uframe, qh,
557                                                         &c_mask);
558                                         if (status == 0)
559                                                 break;
560                                 }
561                         } while (status && frame--);
562
563                 /* qh->period == 0 means every uframe */
564                 } else {
565                         frame = 0;
566                         status = check_intr_schedule (ehci, 0, 0, qh, &c_mask);
567                 }
568                 if (status)
569                         goto done;
570                 qh->start = frame;
571
572                 /* reset S-frame and (maybe) C-frame masks */
573                 qh->hw_info2 &= __constant_cpu_to_le32(~(QH_CMASK | QH_SMASK));
574                 qh->hw_info2 |= qh->period
575                         ? cpu_to_le32 (1 << uframe)
576                         : __constant_cpu_to_le32 (QH_SMASK);
577                 qh->hw_info2 |= c_mask;
578         } else
579                 ehci_dbg (ehci, "reused qh %p schedule\n", qh);
580
581         /* stuff into the periodic schedule */
582         status = qh_link_periodic (ehci, qh);
583 done:
584         return status;
585 }
586
587 static int intr_submit (
588         struct ehci_hcd         *ehci,
589         struct usb_host_endpoint *ep,
590         struct urb              *urb,
591         struct list_head        *qtd_list,
592         gfp_t                   mem_flags
593 ) {
594         unsigned                epnum;
595         unsigned long           flags;
596         struct ehci_qh          *qh;
597         int                     status = 0;
598         struct list_head        empty;
599
600         /* get endpoint and transfer/schedule data */
601         epnum = ep->desc.bEndpointAddress;
602
603         spin_lock_irqsave (&ehci->lock, flags);
604
605         if (unlikely(!test_bit(HCD_FLAG_HW_ACCESSIBLE,
606                                &ehci_to_hcd(ehci)->flags))) {
607                 status = -ESHUTDOWN;
608                 goto done;
609         }
610
611         /* get qh and force any scheduling errors */
612         INIT_LIST_HEAD (&empty);
613         qh = qh_append_tds (ehci, urb, &empty, epnum, &ep->hcpriv);
614         if (qh == NULL) {
615                 status = -ENOMEM;
616                 goto done;
617         }
618         if (qh->qh_state == QH_STATE_IDLE) {
619                 if ((status = qh_schedule (ehci, qh)) != 0)
620                         goto done;
621         }
622
623         /* then queue the urb's tds to the qh */
624         qh = qh_append_tds (ehci, urb, qtd_list, epnum, &ep->hcpriv);
625         BUG_ON (qh == NULL);
626
627         /* ... update usbfs periodic stats */
628         ehci_to_hcd(ehci)->self.bandwidth_int_reqs++;
629
630 done:
631         spin_unlock_irqrestore (&ehci->lock, flags);
632         if (status)
633                 qtd_list_free (ehci, urb, qtd_list);
634
635         return status;
636 }
637
638 /*-------------------------------------------------------------------------*/
639
640 /* ehci_iso_stream ops work with both ITD and SITD */
641
642 static struct ehci_iso_stream *
643 iso_stream_alloc (gfp_t mem_flags)
644 {
645         struct ehci_iso_stream *stream;
646
647         stream = kzalloc(sizeof *stream, mem_flags);
648         if (likely (stream != NULL)) {
649                 INIT_LIST_HEAD(&stream->td_list);
650                 INIT_LIST_HEAD(&stream->free_list);
651                 stream->next_uframe = -1;
652                 stream->refcount = 1;
653         }
654         return stream;
655 }
656
657 static void
658 iso_stream_init (
659         struct ehci_hcd         *ehci,
660         struct ehci_iso_stream  *stream,
661         struct usb_device       *dev,
662         int                     pipe,
663         unsigned                interval
664 )
665 {
666         static const u8 smask_out [] = { 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f };
667
668         u32                     buf1;
669         unsigned                epnum, maxp;
670         int                     is_input;
671         long                    bandwidth;
672
673         /*
674          * this might be a "high bandwidth" highspeed endpoint,
675          * as encoded in the ep descriptor's wMaxPacket field
676          */
677         epnum = usb_pipeendpoint (pipe);
678         is_input = usb_pipein (pipe) ? USB_DIR_IN : 0;
679         maxp = usb_maxpacket(dev, pipe, !is_input);
680         if (is_input) {
681                 buf1 = (1 << 11);
682         } else {
683                 buf1 = 0;
684         }
685
686         /* knows about ITD vs SITD */
687         if (dev->speed == USB_SPEED_HIGH) {
688                 unsigned multi = hb_mult(maxp);
689
690                 stream->highspeed = 1;
691
692                 maxp = max_packet(maxp);
693                 buf1 |= maxp;
694                 maxp *= multi;
695
696                 stream->buf0 = cpu_to_le32 ((epnum << 8) | dev->devnum);
697                 stream->buf1 = cpu_to_le32 (buf1);
698                 stream->buf2 = cpu_to_le32 (multi);
699
700                 /* usbfs wants to report the average usecs per frame tied up
701                  * when transfers on this endpoint are scheduled ...
702                  */
703                 stream->usecs = HS_USECS_ISO (maxp);
704                 bandwidth = stream->usecs * 8;
705                 bandwidth /= 1 << (interval - 1);
706
707         } else {
708                 u32             addr;
709                 int             think_time;
710                 int             hs_transfers;
711
712                 addr = dev->ttport << 24;
713                 if (!ehci_is_TDI(ehci)
714                                 || (dev->tt->hub !=
715                                         ehci_to_hcd(ehci)->self.root_hub))
716                         addr |= dev->tt->hub->devnum << 16;
717                 addr |= epnum << 8;
718                 addr |= dev->devnum;
719                 stream->usecs = HS_USECS_ISO (maxp);
720                 think_time = dev->tt ? dev->tt->think_time : 0;
721                 stream->tt_usecs = NS_TO_US (think_time + usb_calc_bus_time (
722                                 dev->speed, is_input, 1, maxp));
723                 hs_transfers = max (1u, (maxp + 187) / 188);
724                 if (is_input) {
725                         u32     tmp;
726
727                         addr |= 1 << 31;
728                         stream->c_usecs = stream->usecs;
729                         stream->usecs = HS_USECS_ISO (1);
730                         stream->raw_mask = 1;
731
732                         /* c-mask as specified in USB 2.0 11.18.4 3.c */
733                         tmp = (1 << (hs_transfers + 2)) - 1;
734                         stream->raw_mask |= tmp << (8 + 2);
735                 } else
736                         stream->raw_mask = smask_out [hs_transfers - 1];
737                 bandwidth = stream->usecs + stream->c_usecs;
738                 bandwidth /= 1 << (interval + 2);
739
740                 /* stream->splits gets created from raw_mask later */
741                 stream->address = cpu_to_le32 (addr);
742         }
743         stream->bandwidth = bandwidth;
744
745         stream->udev = dev;
746
747         stream->bEndpointAddress = is_input | epnum;
748         stream->interval = interval;
749         stream->maxp = maxp;
750 }
751
752 static void
753 iso_stream_put(struct ehci_hcd *ehci, struct ehci_iso_stream *stream)
754 {
755         stream->refcount--;
756
757         /* free whenever just a dev->ep reference remains.
758          * not like a QH -- no persistent state (toggle, halt)
759          */
760         if (stream->refcount == 1) {
761                 int             is_in;
762
763                 // BUG_ON (!list_empty(&stream->td_list));
764
765                 while (!list_empty (&stream->free_list)) {
766                         struct list_head        *entry;
767
768                         entry = stream->free_list.next;
769                         list_del (entry);
770
771                         /* knows about ITD vs SITD */
772                         if (stream->highspeed) {
773                                 struct ehci_itd         *itd;
774
775                                 itd = list_entry (entry, struct ehci_itd,
776                                                 itd_list);
777                                 dma_pool_free (ehci->itd_pool, itd,
778                                                 itd->itd_dma);
779                         } else {
780                                 struct ehci_sitd        *sitd;
781
782                                 sitd = list_entry (entry, struct ehci_sitd,
783                                                 sitd_list);
784                                 dma_pool_free (ehci->sitd_pool, sitd,
785                                                 sitd->sitd_dma);
786                         }
787                 }
788
789                 is_in = (stream->bEndpointAddress & USB_DIR_IN) ? 0x10 : 0;
790                 stream->bEndpointAddress &= 0x0f;
791                 stream->ep->hcpriv = NULL;
792
793                 if (stream->rescheduled) {
794                         ehci_info (ehci, "ep%d%s-iso rescheduled "
795                                 "%lu times in %lu seconds\n",
796                                 stream->bEndpointAddress, is_in ? "in" : "out",
797                                 stream->rescheduled,
798                                 ((jiffies - stream->start)/HZ)
799                                 );
800                 }
801
802                 kfree(stream);
803         }
804 }
805
806 static inline struct ehci_iso_stream *
807 iso_stream_get (struct ehci_iso_stream *stream)
808 {
809         if (likely (stream != NULL))
810                 stream->refcount++;
811         return stream;
812 }
813
814 static struct ehci_iso_stream *
815 iso_stream_find (struct ehci_hcd *ehci, struct urb *urb)
816 {
817         unsigned                epnum;
818         struct ehci_iso_stream  *stream;
819         struct usb_host_endpoint *ep;
820         unsigned long           flags;
821
822         epnum = usb_pipeendpoint (urb->pipe);
823         if (usb_pipein(urb->pipe))
824                 ep = urb->dev->ep_in[epnum];
825         else
826                 ep = urb->dev->ep_out[epnum];
827
828         spin_lock_irqsave (&ehci->lock, flags);
829         stream = ep->hcpriv;
830
831         if (unlikely (stream == NULL)) {
832                 stream = iso_stream_alloc(GFP_ATOMIC);
833                 if (likely (stream != NULL)) {
834                         /* dev->ep owns the initial refcount */
835                         ep->hcpriv = stream;
836                         stream->ep = ep;
837                         iso_stream_init(ehci, stream, urb->dev, urb->pipe,
838                                         urb->interval);
839                 }
840
841         /* if dev->ep [epnum] is a QH, info1.maxpacket is nonzero */
842         } else if (unlikely (stream->hw_info1 != 0)) {
843                 ehci_dbg (ehci, "dev %s ep%d%s, not iso??\n",
844                         urb->dev->devpath, epnum,
845                         usb_pipein(urb->pipe) ? "in" : "out");
846                 stream = NULL;
847         }
848
849         /* caller guarantees an eventual matching iso_stream_put */
850         stream = iso_stream_get (stream);
851
852         spin_unlock_irqrestore (&ehci->lock, flags);
853         return stream;
854 }
855
856 /*-------------------------------------------------------------------------*/
857
858 /* ehci_iso_sched ops can be ITD-only or SITD-only */
859
860 static struct ehci_iso_sched *
861 iso_sched_alloc (unsigned packets, gfp_t mem_flags)
862 {
863         struct ehci_iso_sched   *iso_sched;
864         int                     size = sizeof *iso_sched;
865
866         size += packets * sizeof (struct ehci_iso_packet);
867         iso_sched = kzalloc(size, mem_flags);
868         if (likely (iso_sched != NULL)) {
869                 INIT_LIST_HEAD (&iso_sched->td_list);
870         }
871         return iso_sched;
872 }
873
874 static inline void
875 itd_sched_init (
876         struct ehci_iso_sched   *iso_sched,
877         struct ehci_iso_stream  *stream,
878         struct urb              *urb
879 )
880 {
881         unsigned        i;
882         dma_addr_t      dma = urb->transfer_dma;
883
884         /* how many uframes are needed for these transfers */
885         iso_sched->span = urb->number_of_packets * stream->interval;
886
887         /* figure out per-uframe itd fields that we'll need later
888          * when we fit new itds into the schedule.
889          */
890         for (i = 0; i < urb->number_of_packets; i++) {
891                 struct ehci_iso_packet  *uframe = &iso_sched->packet [i];
892                 unsigned                length;
893                 dma_addr_t              buf;
894                 u32                     trans;
895
896                 length = urb->iso_frame_desc [i].length;
897                 buf = dma + urb->iso_frame_desc [i].offset;
898
899                 trans = EHCI_ISOC_ACTIVE;
900                 trans |= buf & 0x0fff;
901                 if (unlikely (((i + 1) == urb->number_of_packets))
902                                 && !(urb->transfer_flags & URB_NO_INTERRUPT))
903                         trans |= EHCI_ITD_IOC;
904                 trans |= length << 16;
905                 uframe->transaction = cpu_to_le32 (trans);
906
907                 /* might need to cross a buffer page within a uframe */
908                 uframe->bufp = (buf & ~(u64)0x0fff);
909                 buf += length;
910                 if (unlikely ((uframe->bufp != (buf & ~(u64)0x0fff))))
911                         uframe->cross = 1;
912         }
913 }
914
915 static void
916 iso_sched_free (
917         struct ehci_iso_stream  *stream,
918         struct ehci_iso_sched   *iso_sched
919 )
920 {
921         if (!iso_sched)
922                 return;
923         // caller must hold ehci->lock!
924         list_splice (&iso_sched->td_list, &stream->free_list);
925         kfree (iso_sched);
926 }
927
928 static int
929 itd_urb_transaction (
930         struct ehci_iso_stream  *stream,
931         struct ehci_hcd         *ehci,
932         struct urb              *urb,
933         gfp_t                   mem_flags
934 )
935 {
936         struct ehci_itd         *itd;
937         dma_addr_t              itd_dma;
938         int                     i;
939         unsigned                num_itds;
940         struct ehci_iso_sched   *sched;
941         unsigned long           flags;
942
943         sched = iso_sched_alloc (urb->number_of_packets, mem_flags);
944         if (unlikely (sched == NULL))
945                 return -ENOMEM;
946
947         itd_sched_init (sched, stream, urb);
948
949         if (urb->interval < 8)
950                 num_itds = 1 + (sched->span + 7) / 8;
951         else
952                 num_itds = urb->number_of_packets;
953
954         /* allocate/init ITDs */
955         spin_lock_irqsave (&ehci->lock, flags);
956         for (i = 0; i < num_itds; i++) {
957
958                 /* free_list.next might be cache-hot ... but maybe
959                  * the HC caches it too. avoid that issue for now.
960                  */
961
962                 /* prefer previously-allocated itds */
963                 if (likely (!list_empty(&stream->free_list))) {
964                         itd = list_entry (stream->free_list.prev,
965                                          struct ehci_itd, itd_list);
966                         list_del (&itd->itd_list);
967                         itd_dma = itd->itd_dma;
968                 } else
969                         itd = NULL;
970
971                 if (!itd) {
972                         spin_unlock_irqrestore (&ehci->lock, flags);
973                         itd = dma_pool_alloc (ehci->itd_pool, mem_flags,
974                                         &itd_dma);
975                         spin_lock_irqsave (&ehci->lock, flags);
976                 }
977
978                 if (unlikely (NULL == itd)) {
979                         iso_sched_free (stream, sched);
980                         spin_unlock_irqrestore (&ehci->lock, flags);
981                         return -ENOMEM;
982                 }
983                 memset (itd, 0, sizeof *itd);
984                 itd->itd_dma = itd_dma;
985                 list_add (&itd->itd_list, &sched->td_list);
986         }
987         spin_unlock_irqrestore (&ehci->lock, flags);
988
989         /* temporarily store schedule info in hcpriv */
990         urb->hcpriv = sched;
991         urb->error_count = 0;
992         return 0;
993 }
994
995 /*-------------------------------------------------------------------------*/
996
997 static inline int
998 itd_slot_ok (
999         struct ehci_hcd         *ehci,
1000         u32                     mod,
1001         u32                     uframe,
1002         u8                      usecs,
1003         u32                     period
1004 )
1005 {
1006         uframe %= period;
1007         do {
1008                 /* can't commit more than 80% periodic == 100 usec */
1009                 if (periodic_usecs (ehci, uframe >> 3, uframe & 0x7)
1010                                 > (100 - usecs))
1011                         return 0;
1012
1013                 /* we know urb->interval is 2^N uframes */
1014                 uframe += period;
1015         } while (uframe < mod);
1016         return 1;
1017 }
1018
1019 static inline int
1020 sitd_slot_ok (
1021         struct ehci_hcd         *ehci,
1022         u32                     mod,
1023         struct ehci_iso_stream  *stream,
1024         u32                     uframe,
1025         struct ehci_iso_sched   *sched,
1026         u32                     period_uframes
1027 )
1028 {
1029         u32                     mask, tmp;
1030         u32                     frame, uf;
1031
1032         mask = stream->raw_mask << (uframe & 7);
1033
1034         /* for IN, don't wrap CSPLIT into the next frame */
1035         if (mask & ~0xffff)
1036                 return 0;
1037
1038         /* this multi-pass logic is simple, but performance may
1039          * suffer when the schedule data isn't cached.
1040          */
1041
1042         /* check bandwidth */
1043         uframe %= period_uframes;
1044         do {
1045                 u32             max_used;
1046
1047                 frame = uframe >> 3;
1048                 uf = uframe & 7;
1049
1050                 /* tt must be idle for start(s), any gap, and csplit.
1051                  * assume scheduling slop leaves 10+% for control/bulk.
1052                  */
1053                 if (!tt_no_collision (ehci, period_uframes << 3,
1054                                 stream->udev, frame, mask))
1055                         return 0;
1056
1057                 /* check starts (OUT uses more than one) */
1058                 max_used = 100 - stream->usecs;
1059                 for (tmp = stream->raw_mask & 0xff; tmp; tmp >>= 1, uf++) {
1060                         if (periodic_usecs (ehci, frame, uf) > max_used)
1061                                 return 0;
1062                 }
1063
1064                 /* for IN, check CSPLIT */
1065                 if (stream->c_usecs) {
1066                         uf = uframe & 7;
1067                         max_used = 100 - stream->c_usecs;
1068                         do {
1069                                 tmp = 1 << uf;
1070                                 tmp <<= 8;
1071                                 if ((stream->raw_mask & tmp) == 0)
1072                                         continue;
1073                                 if (periodic_usecs (ehci, frame, uf)
1074                                                 > max_used)
1075                                         return 0;
1076                         } while (++uf < 8);
1077                 }
1078
1079                 /* we know urb->interval is 2^N uframes */
1080                 uframe += period_uframes;
1081         } while (uframe < mod);
1082
1083         stream->splits = cpu_to_le32(stream->raw_mask << (uframe & 7));
1084         return 1;
1085 }
1086
1087 /*
1088  * This scheduler plans almost as far into the future as it has actual
1089  * periodic schedule slots.  (Affected by TUNE_FLS, which defaults to
1090  * "as small as possible" to be cache-friendlier.)  That limits the size
1091  * transfers you can stream reliably; avoid more than 64 msec per urb.
1092  * Also avoid queue depths of less than ehci's worst irq latency (affected
1093  * by the per-urb URB_NO_INTERRUPT hint, the log2_irq_thresh module parameter,
1094  * and other factors); or more than about 230 msec total (for portability,
1095  * given EHCI_TUNE_FLS and the slop).  Or, write a smarter scheduler!
1096  */
1097
1098 #define SCHEDULE_SLOP   10      /* frames */
1099
1100 static int
1101 iso_stream_schedule (
1102         struct ehci_hcd         *ehci,
1103         struct urb              *urb,
1104         struct ehci_iso_stream  *stream
1105 )
1106 {
1107         u32                     now, start, max, period;
1108         int                     status;
1109         unsigned                mod = ehci->periodic_size << 3;
1110         struct ehci_iso_sched   *sched = urb->hcpriv;
1111
1112         if (sched->span > (mod - 8 * SCHEDULE_SLOP)) {
1113                 ehci_dbg (ehci, "iso request %p too long\n", urb);
1114                 status = -EFBIG;
1115                 goto fail;
1116         }
1117
1118         if ((stream->depth + sched->span) > mod) {
1119                 ehci_dbg (ehci, "request %p would overflow (%d+%d>%d)\n",
1120                         urb, stream->depth, sched->span, mod);
1121                 status = -EFBIG;
1122                 goto fail;
1123         }
1124
1125         now = readl (&ehci->regs->frame_index) % mod;
1126
1127         /* when's the last uframe this urb could start? */
1128         max = now + mod;
1129
1130         /* typical case: reuse current schedule. stream is still active,
1131          * and no gaps from host falling behind (irq delays etc)
1132          */
1133         if (likely (!list_empty (&stream->td_list))) {
1134                 start = stream->next_uframe;
1135                 if (start < now)
1136                         start += mod;
1137                 if (likely ((start + sched->span) < max))
1138                         goto ready;
1139                 /* else fell behind; someday, try to reschedule */
1140                 status = -EL2NSYNC;
1141                 goto fail;
1142         }
1143
1144         /* need to schedule; when's the next (u)frame we could start?
1145          * this is bigger than ehci->i_thresh allows; scheduling itself
1146          * isn't free, the slop should handle reasonably slow cpus.  it
1147          * can also help high bandwidth if the dma and irq loads don't
1148          * jump until after the queue is primed.
1149          */
1150         start = SCHEDULE_SLOP * 8 + (now & ~0x07);
1151         start %= mod;
1152         stream->next_uframe = start;
1153
1154         /* NOTE:  assumes URB_ISO_ASAP, to limit complexity/bugs */
1155
1156         period = urb->interval;
1157         if (!stream->highspeed)
1158                 period <<= 3;
1159
1160         /* find a uframe slot with enough bandwidth */
1161         for (; start < (stream->next_uframe + period); start++) {
1162                 int             enough_space;
1163
1164                 /* check schedule: enough space? */
1165                 if (stream->highspeed)
1166                         enough_space = itd_slot_ok (ehci, mod, start,
1167                                         stream->usecs, period);
1168                 else {
1169                         if ((start % 8) >= 6)
1170                                 continue;
1171                         enough_space = sitd_slot_ok (ehci, mod, stream,
1172                                         start, sched, period);
1173                 }
1174
1175                 /* schedule it here if there's enough bandwidth */
1176                 if (enough_space) {
1177                         stream->next_uframe = start % mod;
1178                         goto ready;
1179                 }
1180         }
1181
1182         /* no room in the schedule */
1183         ehci_dbg (ehci, "iso %ssched full %p (now %d max %d)\n",
1184                 list_empty (&stream->td_list) ? "" : "re",
1185                 urb, now, max);
1186         status = -ENOSPC;
1187
1188 fail:
1189         iso_sched_free (stream, sched);
1190         urb->hcpriv = NULL;
1191         return status;
1192
1193 ready:
1194         /* report high speed start in uframes; full speed, in frames */
1195         urb->start_frame = stream->next_uframe;
1196         if (!stream->highspeed)
1197                 urb->start_frame >>= 3;
1198         return 0;
1199 }
1200
1201 /*-------------------------------------------------------------------------*/
1202
1203 static inline void
1204 itd_init (struct ehci_iso_stream *stream, struct ehci_itd *itd)
1205 {
1206         int i;
1207
1208         /* it's been recently zeroed */
1209         itd->hw_next = EHCI_LIST_END;
1210         itd->hw_bufp [0] = stream->buf0;
1211         itd->hw_bufp [1] = stream->buf1;
1212         itd->hw_bufp [2] = stream->buf2;
1213
1214         for (i = 0; i < 8; i++)
1215                 itd->index[i] = -1;
1216
1217         /* All other fields are filled when scheduling */
1218 }
1219
1220 static inline void
1221 itd_patch (
1222         struct ehci_itd         *itd,
1223         struct ehci_iso_sched   *iso_sched,
1224         unsigned                index,
1225         u16                     uframe
1226 )
1227 {
1228         struct ehci_iso_packet  *uf = &iso_sched->packet [index];
1229         unsigned                pg = itd->pg;
1230
1231         // BUG_ON (pg == 6 && uf->cross);
1232
1233         uframe &= 0x07;
1234         itd->index [uframe] = index;
1235
1236         itd->hw_transaction [uframe] = uf->transaction;
1237         itd->hw_transaction [uframe] |= cpu_to_le32 (pg << 12);
1238         itd->hw_bufp [pg] |= cpu_to_le32 (uf->bufp & ~(u32)0);
1239         itd->hw_bufp_hi [pg] |= cpu_to_le32 ((u32)(uf->bufp >> 32));
1240
1241         /* iso_frame_desc[].offset must be strictly increasing */
1242         if (unlikely (uf->cross)) {
1243                 u64     bufp = uf->bufp + 4096;
1244                 itd->pg = ++pg;
1245                 itd->hw_bufp [pg] |= cpu_to_le32 (bufp & ~(u32)0);
1246                 itd->hw_bufp_hi [pg] |= cpu_to_le32 ((u32)(bufp >> 32));
1247         }
1248 }
1249
1250 static inline void
1251 itd_link (struct ehci_hcd *ehci, unsigned frame, struct ehci_itd *itd)
1252 {
1253         /* always prepend ITD/SITD ... only QH tree is order-sensitive */
1254         itd->itd_next = ehci->pshadow [frame];
1255         itd->hw_next = ehci->periodic [frame];
1256         ehci->pshadow [frame].itd = itd;
1257         itd->frame = frame;
1258         wmb ();
1259         ehci->periodic [frame] = cpu_to_le32 (itd->itd_dma) | Q_TYPE_ITD;
1260 }
1261
1262 /* fit urb's itds into the selected schedule slot; activate as needed */
1263 static int
1264 itd_link_urb (
1265         struct ehci_hcd         *ehci,
1266         struct urb              *urb,
1267         unsigned                mod,
1268         struct ehci_iso_stream  *stream
1269 )
1270 {
1271         int                     packet;
1272         unsigned                next_uframe, uframe, frame;
1273         struct ehci_iso_sched   *iso_sched = urb->hcpriv;
1274         struct ehci_itd         *itd;
1275
1276         next_uframe = stream->next_uframe % mod;
1277
1278         if (unlikely (list_empty(&stream->td_list))) {
1279                 ehci_to_hcd(ehci)->self.bandwidth_allocated
1280                                 += stream->bandwidth;
1281                 ehci_vdbg (ehci,
1282                         "schedule devp %s ep%d%s-iso period %d start %d.%d\n",
1283                         urb->dev->devpath, stream->bEndpointAddress & 0x0f,
1284                         (stream->bEndpointAddress & USB_DIR_IN) ? "in" : "out",
1285                         urb->interval,
1286                         next_uframe >> 3, next_uframe & 0x7);
1287                 stream->start = jiffies;
1288         }
1289         ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs++;
1290
1291         /* fill iTDs uframe by uframe */
1292         for (packet = 0, itd = NULL; packet < urb->number_of_packets; ) {
1293                 if (itd == NULL) {
1294                         /* ASSERT:  we have all necessary itds */
1295                         // BUG_ON (list_empty (&iso_sched->td_list));
1296
1297                         /* ASSERT:  no itds for this endpoint in this uframe */
1298
1299                         itd = list_entry (iso_sched->td_list.next,
1300                                         struct ehci_itd, itd_list);
1301                         list_move_tail (&itd->itd_list, &stream->td_list);
1302                         itd->stream = iso_stream_get (stream);
1303                         itd->urb = usb_get_urb (urb);
1304                         itd_init (stream, itd);
1305                 }
1306
1307                 uframe = next_uframe & 0x07;
1308                 frame = next_uframe >> 3;
1309
1310                 itd->usecs [uframe] = stream->usecs;
1311                 itd_patch (itd, iso_sched, packet, uframe);
1312
1313                 next_uframe += stream->interval;
1314                 stream->depth += stream->interval;
1315                 next_uframe %= mod;
1316                 packet++;
1317
1318                 /* link completed itds into the schedule */
1319                 if (((next_uframe >> 3) != frame)
1320                                 || packet == urb->number_of_packets) {
1321                         itd_link (ehci, frame % ehci->periodic_size, itd);
1322                         itd = NULL;
1323                 }
1324         }
1325         stream->next_uframe = next_uframe;
1326
1327         /* don't need that schedule data any more */
1328         iso_sched_free (stream, iso_sched);
1329         urb->hcpriv = NULL;
1330
1331         timer_action (ehci, TIMER_IO_WATCHDOG);
1332         if (unlikely (!ehci->periodic_sched++))
1333                 return enable_periodic (ehci);
1334         return 0;
1335 }
1336
1337 #define ISO_ERRS (EHCI_ISOC_BUF_ERR | EHCI_ISOC_BABBLE | EHCI_ISOC_XACTERR)
1338
1339 static unsigned
1340 itd_complete (
1341         struct ehci_hcd *ehci,
1342         struct ehci_itd *itd,
1343         struct pt_regs  *regs
1344 ) {
1345         struct urb                              *urb = itd->urb;
1346         struct usb_iso_packet_descriptor        *desc;
1347         u32                                     t;
1348         unsigned                                uframe;
1349         int                                     urb_index = -1;
1350         struct ehci_iso_stream                  *stream = itd->stream;
1351         struct usb_device                       *dev;
1352
1353         /* for each uframe with a packet */
1354         for (uframe = 0; uframe < 8; uframe++) {
1355                 if (likely (itd->index[uframe] == -1))
1356                         continue;
1357                 urb_index = itd->index[uframe];
1358                 desc = &urb->iso_frame_desc [urb_index];
1359
1360                 t = le32_to_cpup (&itd->hw_transaction [uframe]);
1361                 itd->hw_transaction [uframe] = 0;
1362                 stream->depth -= stream->interval;
1363
1364                 /* report transfer status */
1365                 if (unlikely (t & ISO_ERRS)) {
1366                         urb->error_count++;
1367                         if (t & EHCI_ISOC_BUF_ERR)
1368                                 desc->status = usb_pipein (urb->pipe)
1369                                         ? -ENOSR  /* hc couldn't read */
1370                                         : -ECOMM; /* hc couldn't write */
1371                         else if (t & EHCI_ISOC_BABBLE)
1372                                 desc->status = -EOVERFLOW;
1373                         else /* (t & EHCI_ISOC_XACTERR) */
1374                                 desc->status = -EPROTO;
1375
1376                         /* HC need not update length with this error */
1377                         if (!(t & EHCI_ISOC_BABBLE))
1378                                 desc->actual_length = EHCI_ITD_LENGTH (t);
1379                 } else if (likely ((t & EHCI_ISOC_ACTIVE) == 0)) {
1380                         desc->status = 0;
1381                         desc->actual_length = EHCI_ITD_LENGTH (t);
1382                 }
1383         }
1384
1385         usb_put_urb (urb);
1386         itd->urb = NULL;
1387         itd->stream = NULL;
1388         list_move (&itd->itd_list, &stream->free_list);
1389         iso_stream_put (ehci, stream);
1390
1391         /* handle completion now? */
1392         if (likely ((urb_index + 1) != urb->number_of_packets))
1393                 return 0;
1394
1395         /* ASSERT: it's really the last itd for this urb
1396         list_for_each_entry (itd, &stream->td_list, itd_list)
1397                 BUG_ON (itd->urb == urb);
1398          */
1399
1400         /* give urb back to the driver ... can be out-of-order */
1401         dev = urb->dev;
1402         ehci_urb_done (ehci, urb, regs);
1403         urb = NULL;
1404
1405         /* defer stopping schedule; completion can submit */
1406         ehci->periodic_sched--;
1407         if (unlikely (!ehci->periodic_sched))
1408                 (void) disable_periodic (ehci);
1409         ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs--;
1410
1411         if (unlikely (list_empty (&stream->td_list))) {
1412                 ehci_to_hcd(ehci)->self.bandwidth_allocated
1413                                 -= stream->bandwidth;
1414                 ehci_vdbg (ehci,
1415                         "deschedule devp %s ep%d%s-iso\n",
1416                         dev->devpath, stream->bEndpointAddress & 0x0f,
1417                         (stream->bEndpointAddress & USB_DIR_IN) ? "in" : "out");
1418         }
1419         iso_stream_put (ehci, stream);
1420
1421         return 1;
1422 }
1423
1424 /*-------------------------------------------------------------------------*/
1425
1426 static int itd_submit (struct ehci_hcd *ehci, struct urb *urb,
1427         gfp_t mem_flags)
1428 {
1429         int                     status = -EINVAL;
1430         unsigned long           flags;
1431         struct ehci_iso_stream  *stream;
1432
1433         /* Get iso_stream head */
1434         stream = iso_stream_find (ehci, urb);
1435         if (unlikely (stream == NULL)) {
1436                 ehci_dbg (ehci, "can't get iso stream\n");
1437                 return -ENOMEM;
1438         }
1439         if (unlikely (urb->interval != stream->interval)) {
1440                 ehci_dbg (ehci, "can't change iso interval %d --> %d\n",
1441                         stream->interval, urb->interval);
1442                 goto done;
1443         }
1444
1445 #ifdef EHCI_URB_TRACE
1446         ehci_dbg (ehci,
1447                 "%s %s urb %p ep%d%s len %d, %d pkts %d uframes [%p]\n",
1448                 __FUNCTION__, urb->dev->devpath, urb,
1449                 usb_pipeendpoint (urb->pipe),
1450                 usb_pipein (urb->pipe) ? "in" : "out",
1451                 urb->transfer_buffer_length,
1452                 urb->number_of_packets, urb->interval,
1453                 stream);
1454 #endif
1455
1456         /* allocate ITDs w/o locking anything */
1457         status = itd_urb_transaction (stream, ehci, urb, mem_flags);
1458         if (unlikely (status < 0)) {
1459                 ehci_dbg (ehci, "can't init itds\n");
1460                 goto done;
1461         }
1462
1463         /* schedule ... need to lock */
1464         spin_lock_irqsave (&ehci->lock, flags);
1465         if (unlikely(!test_bit(HCD_FLAG_HW_ACCESSIBLE,
1466                                &ehci_to_hcd(ehci)->flags)))
1467                 status = -ESHUTDOWN;
1468         else
1469                 status = iso_stream_schedule (ehci, urb, stream);
1470         if (likely (status == 0))
1471                 itd_link_urb (ehci, urb, ehci->periodic_size << 3, stream);
1472         spin_unlock_irqrestore (&ehci->lock, flags);
1473
1474 done:
1475         if (unlikely (status < 0))
1476                 iso_stream_put (ehci, stream);
1477         return status;
1478 }
1479
1480 #ifdef CONFIG_USB_EHCI_SPLIT_ISO
1481
1482 /*-------------------------------------------------------------------------*/
1483
1484 /*
1485  * "Split ISO TDs" ... used for USB 1.1 devices going through the
1486  * TTs in USB 2.0 hubs.  These need microframe scheduling.
1487  */
1488
1489 static inline void
1490 sitd_sched_init (
1491         struct ehci_iso_sched   *iso_sched,
1492         struct ehci_iso_stream  *stream,
1493         struct urb              *urb
1494 )
1495 {
1496         unsigned        i;
1497         dma_addr_t      dma = urb->transfer_dma;
1498
1499         /* how many frames are needed for these transfers */
1500         iso_sched->span = urb->number_of_packets * stream->interval;
1501
1502         /* figure out per-frame sitd fields that we'll need later
1503          * when we fit new sitds into the schedule.
1504          */
1505         for (i = 0; i < urb->number_of_packets; i++) {
1506                 struct ehci_iso_packet  *packet = &iso_sched->packet [i];
1507                 unsigned                length;
1508                 dma_addr_t              buf;
1509                 u32                     trans;
1510
1511                 length = urb->iso_frame_desc [i].length & 0x03ff;
1512                 buf = dma + urb->iso_frame_desc [i].offset;
1513
1514                 trans = SITD_STS_ACTIVE;
1515                 if (((i + 1) == urb->number_of_packets)
1516                                 && !(urb->transfer_flags & URB_NO_INTERRUPT))
1517                         trans |= SITD_IOC;
1518                 trans |= length << 16;
1519                 packet->transaction = cpu_to_le32 (trans);
1520
1521                 /* might need to cross a buffer page within a td */
1522                 packet->bufp = buf;
1523                 packet->buf1 = (buf + length) & ~0x0fff;
1524                 if (packet->buf1 != (buf & ~(u64)0x0fff))
1525                         packet->cross = 1;
1526
1527                 /* OUT uses multiple start-splits */ 
1528                 if (stream->bEndpointAddress & USB_DIR_IN)
1529                         continue;
1530                 length = (length + 187) / 188;
1531                 if (length > 1) /* BEGIN vs ALL */
1532                         length |= 1 << 3;
1533                 packet->buf1 |= length;
1534         }
1535 }
1536
1537 static int
1538 sitd_urb_transaction (
1539         struct ehci_iso_stream  *stream,
1540         struct ehci_hcd         *ehci,
1541         struct urb              *urb,
1542         gfp_t                   mem_flags
1543 )
1544 {
1545         struct ehci_sitd        *sitd;
1546         dma_addr_t              sitd_dma;
1547         int                     i;
1548         struct ehci_iso_sched   *iso_sched;
1549         unsigned long           flags;
1550
1551         iso_sched = iso_sched_alloc (urb->number_of_packets, mem_flags);
1552         if (iso_sched == NULL)
1553                 return -ENOMEM;
1554
1555         sitd_sched_init (iso_sched, stream, urb);
1556
1557         /* allocate/init sITDs */
1558         spin_lock_irqsave (&ehci->lock, flags);
1559         for (i = 0; i < urb->number_of_packets; i++) {
1560
1561                 /* NOTE:  for now, we don't try to handle wraparound cases
1562                  * for IN (using sitd->hw_backpointer, like a FSTN), which
1563                  * means we never need two sitds for full speed packets.
1564                  */
1565
1566                 /* free_list.next might be cache-hot ... but maybe
1567                  * the HC caches it too. avoid that issue for now.
1568                  */
1569
1570                 /* prefer previously-allocated sitds */
1571                 if (!list_empty(&stream->free_list)) {
1572                         sitd = list_entry (stream->free_list.prev,
1573                                          struct ehci_sitd, sitd_list);
1574                         list_del (&sitd->sitd_list);
1575                         sitd_dma = sitd->sitd_dma;
1576                 } else
1577                         sitd = NULL;
1578
1579                 if (!sitd) {
1580                         spin_unlock_irqrestore (&ehci->lock, flags);
1581                         sitd = dma_pool_alloc (ehci->sitd_pool, mem_flags,
1582                                         &sitd_dma);
1583                         spin_lock_irqsave (&ehci->lock, flags);
1584                 }
1585
1586                 if (!sitd) {
1587                         iso_sched_free (stream, iso_sched);
1588                         spin_unlock_irqrestore (&ehci->lock, flags);
1589                         return -ENOMEM;
1590                 }
1591                 memset (sitd, 0, sizeof *sitd);
1592                 sitd->sitd_dma = sitd_dma;
1593                 list_add (&sitd->sitd_list, &iso_sched->td_list);
1594         }
1595
1596         /* temporarily store schedule info in hcpriv */
1597         urb->hcpriv = iso_sched;
1598         urb->error_count = 0;
1599
1600         spin_unlock_irqrestore (&ehci->lock, flags);
1601         return 0;
1602 }
1603
1604 /*-------------------------------------------------------------------------*/
1605
1606 static inline void
1607 sitd_patch (
1608         struct ehci_iso_stream  *stream,
1609         struct ehci_sitd        *sitd,
1610         struct ehci_iso_sched   *iso_sched,
1611         unsigned                index
1612 )
1613 {
1614         struct ehci_iso_packet  *uf = &iso_sched->packet [index];
1615         u64                     bufp = uf->bufp;
1616
1617         sitd->hw_next = EHCI_LIST_END;
1618         sitd->hw_fullspeed_ep = stream->address;
1619         sitd->hw_uframe = stream->splits;
1620         sitd->hw_results = uf->transaction;
1621         sitd->hw_backpointer = EHCI_LIST_END;
1622
1623         bufp = uf->bufp;
1624         sitd->hw_buf [0] = cpu_to_le32 (bufp);
1625         sitd->hw_buf_hi [0] = cpu_to_le32 (bufp >> 32);
1626
1627         sitd->hw_buf [1] = cpu_to_le32 (uf->buf1);
1628         if (uf->cross)
1629                 bufp += 4096;
1630         sitd->hw_buf_hi [1] = cpu_to_le32 (bufp >> 32);
1631         sitd->index = index;
1632 }
1633
1634 static inline void
1635 sitd_link (struct ehci_hcd *ehci, unsigned frame, struct ehci_sitd *sitd)
1636 {
1637         /* note: sitd ordering could matter (CSPLIT then SSPLIT) */
1638         sitd->sitd_next = ehci->pshadow [frame];
1639         sitd->hw_next = ehci->periodic [frame];
1640         ehci->pshadow [frame].sitd = sitd;
1641         sitd->frame = frame;
1642         wmb ();
1643         ehci->periodic [frame] = cpu_to_le32 (sitd->sitd_dma) | Q_TYPE_SITD;
1644 }
1645
1646 /* fit urb's sitds into the selected schedule slot; activate as needed */
1647 static int
1648 sitd_link_urb (
1649         struct ehci_hcd         *ehci,
1650         struct urb              *urb,
1651         unsigned                mod,
1652         struct ehci_iso_stream  *stream
1653 )
1654 {
1655         int                     packet;
1656         unsigned                next_uframe;
1657         struct ehci_iso_sched   *sched = urb->hcpriv;
1658         struct ehci_sitd        *sitd;
1659
1660         next_uframe = stream->next_uframe;
1661
1662         if (list_empty(&stream->td_list)) {
1663                 /* usbfs ignores TT bandwidth */
1664                 ehci_to_hcd(ehci)->self.bandwidth_allocated
1665                                 += stream->bandwidth;
1666                 ehci_vdbg (ehci,
1667                         "sched devp %s ep%d%s-iso [%d] %dms/%04x\n",
1668                         urb->dev->devpath, stream->bEndpointAddress & 0x0f,
1669                         (stream->bEndpointAddress & USB_DIR_IN) ? "in" : "out",
1670                         (next_uframe >> 3) % ehci->periodic_size,
1671                         stream->interval, le32_to_cpu (stream->splits));
1672                 stream->start = jiffies;
1673         }
1674         ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs++;
1675
1676         /* fill sITDs frame by frame */
1677         for (packet = 0, sitd = NULL;
1678                         packet < urb->number_of_packets;
1679                         packet++) {
1680
1681                 /* ASSERT:  we have all necessary sitds */
1682                 BUG_ON (list_empty (&sched->td_list));
1683
1684                 /* ASSERT:  no itds for this endpoint in this frame */
1685
1686                 sitd = list_entry (sched->td_list.next,
1687                                 struct ehci_sitd, sitd_list);
1688                 list_move_tail (&sitd->sitd_list, &stream->td_list);
1689                 sitd->stream = iso_stream_get (stream);
1690                 sitd->urb = usb_get_urb (urb);
1691
1692                 sitd_patch (stream, sitd, sched, packet);
1693                 sitd_link (ehci, (next_uframe >> 3) % ehci->periodic_size,
1694                                 sitd);
1695
1696                 next_uframe += stream->interval << 3;
1697                 stream->depth += stream->interval << 3;
1698         }
1699         stream->next_uframe = next_uframe % mod;
1700
1701         /* don't need that schedule data any more */
1702         iso_sched_free (stream, sched);
1703         urb->hcpriv = NULL;
1704
1705         timer_action (ehci, TIMER_IO_WATCHDOG);
1706         if (!ehci->periodic_sched++)
1707                 return enable_periodic (ehci);
1708         return 0;
1709 }
1710
1711 /*-------------------------------------------------------------------------*/
1712
1713 #define SITD_ERRS (SITD_STS_ERR | SITD_STS_DBE | SITD_STS_BABBLE \
1714                                 | SITD_STS_XACT | SITD_STS_MMF)
1715
1716 static unsigned
1717 sitd_complete (
1718         struct ehci_hcd         *ehci,
1719         struct ehci_sitd        *sitd,
1720         struct pt_regs          *regs
1721 ) {
1722         struct urb                              *urb = sitd->urb;
1723         struct usb_iso_packet_descriptor        *desc;
1724         u32                                     t;
1725         int                                     urb_index = -1;
1726         struct ehci_iso_stream                  *stream = sitd->stream;
1727         struct usb_device                       *dev;
1728
1729         urb_index = sitd->index;
1730         desc = &urb->iso_frame_desc [urb_index];
1731         t = le32_to_cpup (&sitd->hw_results);
1732
1733         /* report transfer status */
1734         if (t & SITD_ERRS) {
1735                 urb->error_count++;
1736                 if (t & SITD_STS_DBE)
1737                         desc->status = usb_pipein (urb->pipe)
1738                                 ? -ENOSR  /* hc couldn't read */
1739                                 : -ECOMM; /* hc couldn't write */
1740                 else if (t & SITD_STS_BABBLE)
1741                         desc->status = -EOVERFLOW;
1742                 else /* XACT, MMF, etc */
1743                         desc->status = -EPROTO;
1744         } else {
1745                 desc->status = 0;
1746                 desc->actual_length = desc->length - SITD_LENGTH (t);
1747         }
1748
1749         usb_put_urb (urb);
1750         sitd->urb = NULL;
1751         sitd->stream = NULL;
1752         list_move (&sitd->sitd_list, &stream->free_list);
1753         stream->depth -= stream->interval << 3;
1754         iso_stream_put (ehci, stream);
1755
1756         /* handle completion now? */
1757         if ((urb_index + 1) != urb->number_of_packets)
1758                 return 0;
1759
1760         /* ASSERT: it's really the last sitd for this urb
1761         list_for_each_entry (sitd, &stream->td_list, sitd_list)
1762                 BUG_ON (sitd->urb == urb);
1763          */
1764
1765         /* give urb back to the driver */
1766         dev = urb->dev;
1767         ehci_urb_done (ehci, urb, regs);
1768         urb = NULL;
1769
1770         /* defer stopping schedule; completion can submit */
1771         ehci->periodic_sched--;
1772         if (!ehci->periodic_sched)
1773                 (void) disable_periodic (ehci);
1774         ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs--;
1775
1776         if (list_empty (&stream->td_list)) {
1777                 ehci_to_hcd(ehci)->self.bandwidth_allocated
1778                                 -= stream->bandwidth;
1779                 ehci_vdbg (ehci,
1780                         "deschedule devp %s ep%d%s-iso\n",
1781                         dev->devpath, stream->bEndpointAddress & 0x0f,
1782                         (stream->bEndpointAddress & USB_DIR_IN) ? "in" : "out");
1783         }
1784         iso_stream_put (ehci, stream);
1785
1786         return 1;
1787 }
1788
1789
1790 static int sitd_submit (struct ehci_hcd *ehci, struct urb *urb,
1791         gfp_t mem_flags)
1792 {
1793         int                     status = -EINVAL;
1794         unsigned long           flags;
1795         struct ehci_iso_stream  *stream;
1796
1797         /* Get iso_stream head */
1798         stream = iso_stream_find (ehci, urb);
1799         if (stream == NULL) {
1800                 ehci_dbg (ehci, "can't get iso stream\n");
1801                 return -ENOMEM;
1802         }
1803         if (urb->interval != stream->interval) {
1804                 ehci_dbg (ehci, "can't change iso interval %d --> %d\n",
1805                         stream->interval, urb->interval);
1806                 goto done;
1807         }
1808
1809 #ifdef EHCI_URB_TRACE
1810         ehci_dbg (ehci,
1811                 "submit %p dev%s ep%d%s-iso len %d\n",
1812                 urb, urb->dev->devpath,
1813                 usb_pipeendpoint (urb->pipe),
1814                 usb_pipein (urb->pipe) ? "in" : "out",
1815                 urb->transfer_buffer_length);
1816 #endif
1817
1818         /* allocate SITDs */
1819         status = sitd_urb_transaction (stream, ehci, urb, mem_flags);
1820         if (status < 0) {
1821                 ehci_dbg (ehci, "can't init sitds\n");
1822                 goto done;
1823         }
1824
1825         /* schedule ... need to lock */
1826         spin_lock_irqsave (&ehci->lock, flags);
1827         if (unlikely(!test_bit(HCD_FLAG_HW_ACCESSIBLE,
1828                                &ehci_to_hcd(ehci)->flags)))
1829                 status = -ESHUTDOWN;
1830         else
1831                 status = iso_stream_schedule (ehci, urb, stream);
1832         if (status == 0)
1833                 sitd_link_urb (ehci, urb, ehci->periodic_size << 3, stream);
1834         spin_unlock_irqrestore (&ehci->lock, flags);
1835
1836 done:
1837         if (status < 0)
1838                 iso_stream_put (ehci, stream);
1839         return status;
1840 }
1841
1842 #else
1843
1844 static inline int
1845 sitd_submit (struct ehci_hcd *ehci, struct urb *urb, gfp_t mem_flags)
1846 {
1847         ehci_dbg (ehci, "split iso support is disabled\n");
1848         return -ENOSYS;
1849 }
1850
1851 static inline unsigned
1852 sitd_complete (
1853         struct ehci_hcd         *ehci,
1854         struct ehci_sitd        *sitd,
1855         struct pt_regs          *regs
1856 ) {
1857         ehci_err (ehci, "sitd_complete %p?\n", sitd);
1858         return 0;
1859 }
1860
1861 #endif /* USB_EHCI_SPLIT_ISO */
1862
1863 /*-------------------------------------------------------------------------*/
1864
1865 static void
1866 scan_periodic (struct ehci_hcd *ehci, struct pt_regs *regs)
1867 {
1868         unsigned        frame, clock, now_uframe, mod;
1869         unsigned        modified;
1870
1871         mod = ehci->periodic_size << 3;
1872
1873         /*
1874          * When running, scan from last scan point up to "now"
1875          * else clean up by scanning everything that's left.
1876          * Touches as few pages as possible:  cache-friendly.
1877          */
1878         now_uframe = ehci->next_uframe;
1879         if (HC_IS_RUNNING (ehci_to_hcd(ehci)->state))
1880                 clock = readl (&ehci->regs->frame_index);
1881         else
1882                 clock = now_uframe + mod - 1;
1883         clock %= mod;
1884
1885         for (;;) {
1886                 union ehci_shadow       q, *q_p;
1887                 __le32                  type, *hw_p;
1888                 unsigned                uframes;
1889
1890                 /* don't scan past the live uframe */
1891                 frame = now_uframe >> 3;
1892                 if (frame == (clock >> 3))
1893                         uframes = now_uframe & 0x07;
1894                 else {
1895                         /* safe to scan the whole frame at once */
1896                         now_uframe |= 0x07;
1897                         uframes = 8;
1898                 }
1899
1900 restart:
1901                 /* scan each element in frame's queue for completions */
1902                 q_p = &ehci->pshadow [frame];
1903                 hw_p = &ehci->periodic [frame];
1904                 q.ptr = q_p->ptr;
1905                 type = Q_NEXT_TYPE (*hw_p);
1906                 modified = 0;
1907
1908                 while (q.ptr != NULL) {
1909                         unsigned                uf;
1910                         union ehci_shadow       temp;
1911                         int                     live;
1912
1913                         live = HC_IS_RUNNING (ehci_to_hcd(ehci)->state);
1914                         switch (type) {
1915                         case Q_TYPE_QH:
1916                                 /* handle any completions */
1917                                 temp.qh = qh_get (q.qh);
1918                                 type = Q_NEXT_TYPE (q.qh->hw_next);
1919                                 q = q.qh->qh_next;
1920                                 modified = qh_completions (ehci, temp.qh, regs);
1921                                 if (unlikely (list_empty (&temp.qh->qtd_list)))
1922                                         intr_deschedule (ehci, temp.qh);
1923                                 qh_put (temp.qh);
1924                                 break;
1925                         case Q_TYPE_FSTN:
1926                                 /* for "save place" FSTNs, look at QH entries
1927                                  * in the previous frame for completions.
1928                                  */
1929                                 if (q.fstn->hw_prev != EHCI_LIST_END) {
1930                                         dbg ("ignoring completions from FSTNs");
1931                                 }
1932                                 type = Q_NEXT_TYPE (q.fstn->hw_next);
1933                                 q = q.fstn->fstn_next;
1934                                 break;
1935                         case Q_TYPE_ITD:
1936                                 /* skip itds for later in the frame */
1937                                 rmb ();
1938                                 for (uf = live ? uframes : 8; uf < 8; uf++) {
1939                                         if (0 == (q.itd->hw_transaction [uf]
1940                                                         & ITD_ACTIVE))
1941                                                 continue;
1942                                         q_p = &q.itd->itd_next;
1943                                         hw_p = &q.itd->hw_next;
1944                                         type = Q_NEXT_TYPE (q.itd->hw_next);
1945                                         q = *q_p;
1946                                         break;
1947                                 }
1948                                 if (uf != 8)
1949                                         break;
1950
1951                                 /* this one's ready ... HC won't cache the
1952                                  * pointer for much longer, if at all.
1953                                  */
1954                                 *q_p = q.itd->itd_next;
1955                                 *hw_p = q.itd->hw_next;
1956                                 type = Q_NEXT_TYPE (q.itd->hw_next);
1957                                 wmb();
1958                                 modified = itd_complete (ehci, q.itd, regs);
1959                                 q = *q_p;
1960                                 break;
1961                         case Q_TYPE_SITD:
1962                                 if ((q.sitd->hw_results & SITD_ACTIVE)
1963                                                 && live) {
1964                                         q_p = &q.sitd->sitd_next;
1965                                         hw_p = &q.sitd->hw_next;
1966                                         type = Q_NEXT_TYPE (q.sitd->hw_next);
1967                                         q = *q_p;
1968                                         break;
1969                                 }
1970                                 *q_p = q.sitd->sitd_next;
1971                                 *hw_p = q.sitd->hw_next;
1972                                 type = Q_NEXT_TYPE (q.sitd->hw_next);
1973                                 wmb();
1974                                 modified = sitd_complete (ehci, q.sitd, regs);
1975                                 q = *q_p;
1976                                 break;
1977                         default:
1978                                 dbg ("corrupt type %d frame %d shadow %p",
1979                                         type, frame, q.ptr);
1980                                 // BUG ();
1981                                 q.ptr = NULL;
1982                         }
1983
1984                         /* assume completion callbacks modify the queue */
1985                         if (unlikely (modified))
1986                                 goto restart;
1987                 }
1988
1989                 /* stop when we catch up to the HC */
1990
1991                 // FIXME:  this assumes we won't get lapped when
1992                 // latencies climb; that should be rare, but...
1993                 // detect it, and just go all the way around.
1994                 // FLR might help detect this case, so long as latencies
1995                 // don't exceed periodic_size msec (default 1.024 sec).
1996
1997                 // FIXME:  likewise assumes HC doesn't halt mid-scan
1998
1999                 if (now_uframe == clock) {
2000                         unsigned        now;
2001
2002                         if (!HC_IS_RUNNING (ehci_to_hcd(ehci)->state))
2003                                 break;
2004                         ehci->next_uframe = now_uframe;
2005                         now = readl (&ehci->regs->frame_index) % mod;
2006                         if (now_uframe == now)
2007                                 break;
2008
2009                         /* rescan the rest of this frame, then ... */
2010                         clock = now;
2011                 } else {
2012                         now_uframe++;
2013                         now_uframe %= mod;
2014                 }
2015         } 
2016 }