drivers/usb/host/ehci-q.c

   1 /*
   2  * Copyright (C) 2001-2004 by David Brownell
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License as published by the
   6  * Free Software Foundation; either version 2 of the License, or (at your
   7  * option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  11  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software Foundation,
  16  * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 /* this file is part of ehci-hcd.c */
  20
  21 /*-------------------------------------------------------------------------*/
  22
  23 /*
  24  * EHCI hardware queue manipulation ... the core.  QH/QTD manipulation.
  25  *
  26  * Control, bulk, and interrupt traffic all use "qh" lists.  They list "qtd"
  27  * entries describing USB transactions, max 16-20kB/entry (with 4kB-aligned
  28  * buffers needed for the larger number).  We use one QH per endpoint, queue
  29  * multiple urbs (all three types) per endpoint.  URBs may need several qtds.
  30  *
  31  * ISO traffic uses "ISO TD" (itd, and sitd) records, and (along with
  32  * interrupts) needs careful scheduling.  Performance improvements can be
  33  * an ongoing challenge.  That's in "ehci-sched.c".
  34  *
  35  * USB 1.1 devices are handled (a) by "companion" OHCI or UHCI root hubs,
  36  * or otherwise through transaction translators (TTs) in USB 2.0 hubs using
  37  * (b) special fields in qh entries or (c) split iso entries.  TTs will
  38  * buffer low/full speed data so the host collects it at high speed.
  39  */
  40
  41 /*-------------------------------------------------------------------------*/
  42
  43 /* fill a qtd, returning how much of the buffer we were able to queue up */
  44
  45 static int
  46 qtd_fill(struct ehci_hcd *ehci, struct ehci_qtd *qtd, dma_addr_t buf,
  47                   size_t len, int token, int maxpacket)
  48 {
  49         int     i, count;
  50         u64     addr = buf;
  51
  52         /* one buffer entry per 4K ... first might be short or unaligned */
  53         qtd->hw_buf[0] = cpu_to_hc32(ehci, (u32)addr);
  54         qtd->hw_buf_hi[0] = cpu_to_hc32(ehci, (u32)(addr >> 32));
  55         count = 0x1000 - (buf & 0x0fff);        /* rest of that page */
  56         if (likely (len < count))               /* ... iff needed */
  57                 count = len;
  58         else {
  59                 buf +=  0x1000;
  60                 buf &= ~0x0fff;
  61
  62                 /* per-qtd limit: from 16K to 20K (best alignment) */
  63                 for (i = 1; count < len && i < 5; i++) {
  64                         addr = buf;
  65                         qtd->hw_buf[i] = cpu_to_hc32(ehci, (u32)addr);
  66                         qtd->hw_buf_hi[i] = cpu_to_hc32(ehci,
  67                                         (u32)(addr >> 32));
  68                         buf += 0x1000;
  69                         if ((count + 0x1000) < len)
  70                                 count += 0x1000;
  71                         else
  72                                 count = len;
  73                 }
  74
  75                 /* short packets may only terminate transfers */
  76                 if (count != len)
  77                         count -= (count % maxpacket);
  78         }
  79         qtd->hw_token = cpu_to_hc32(ehci, (count << 16) | token);
  80         qtd->length = count;
  81
  82         return count;
  83 }
  84
  85 /*-------------------------------------------------------------------------*/
  86
  87 static inline void
  88 qh_update (struct ehci_hcd *ehci, struct ehci_qh *qh, struct ehci_qtd *qtd)
  89 {
  90         struct ehci_qh_hw *hw = qh->hw;
  91
  92         /* writes to an active overlay are unsafe */
  93         BUG_ON(qh->qh_state != QH_STATE_IDLE);
  94
  95         hw->hw_qtd_next = QTD_NEXT(ehci, qtd->qtd_dma);
  96         hw->hw_alt_next = EHCI_LIST_END(ehci);
  97
  98         /* Except for control endpoints, we make hardware maintain data
  99          * toggle (like OHCI) ... here (re)initialize the toggle in the QH,
 100          * and set the pseudo-toggle in udev. Only usb_clear_halt() will
 101          * ever clear it.
 102          */
 103         if (!(hw->hw_info1 & cpu_to_hc32(ehci, 1 << 14))) {
 104                 unsigned        is_out, epnum;
 105
 106                 is_out = qh->is_out;
 107                 epnum = (hc32_to_cpup(ehci, &hw->hw_info1) >> 8) & 0x0f;
 108                 if (unlikely (!usb_gettoggle (qh->dev, epnum, is_out))) {
 109                         hw->hw_token &= ~cpu_to_hc32(ehci, QTD_TOGGLE);
 110                         usb_settoggle (qh->dev, epnum, is_out, 1);
 111                 }
 112         }
 113
 114         hw->hw_token &= cpu_to_hc32(ehci, QTD_TOGGLE | QTD_STS_PING);
 115 }
 116
 117 /* if it weren't for a common silicon quirk (writing the dummy into the qh
 118  * overlay, so qh->hw_token wrongly becomes inactive/halted), only fault
 119  * recovery (including urb dequeue) would need software changes to a QH...
 120  */
 121 static void
 122 qh_refresh (struct ehci_hcd *ehci, struct ehci_qh *qh)
 123 {
 124         struct ehci_qtd *qtd;
 125
 126         if (list_empty (&qh->qtd_list))
 127                 qtd = qh->dummy;
 128         else {
 129                 qtd = list_entry (qh->qtd_list.next,
 130                                 struct ehci_qtd, qtd_list);
 131                 /*
 132                  * first qtd may already be partially processed.
 133                  * If we come here during unlink, the QH overlay region
 134                  * might have reference to the just unlinked qtd. The
 135                  * qtd is updated in qh_completions(). Update the QH
 136                  * overlay here.
 137                  */
 138                 if (cpu_to_hc32(ehci, qtd->qtd_dma) == qh->hw->hw_current) {
 139                         qh->hw->hw_qtd_next = qtd->hw_next;
 140                         qtd = NULL;
 141                 }
 142         }
 143
 144         if (qtd)
 145                 qh_update (ehci, qh, qtd);
 146 }
 147
 148 /*-------------------------------------------------------------------------*/
 149
 150 static void qh_link_async(struct ehci_hcd *ehci, struct ehci_qh *qh);
 151
 152 static void ehci_clear_tt_buffer_complete(struct usb_hcd *hcd,
 153                 struct usb_host_endpoint *ep)
 154 {
 155         struct ehci_hcd         *ehci = hcd_to_ehci(hcd);
 156         struct ehci_qh          *qh = ep->hcpriv;
 157         unsigned long           flags;
 158
 159         spin_lock_irqsave(&ehci->lock, flags);
 160         qh->clearing_tt = 0;
 161         if (qh->qh_state == QH_STATE_IDLE && !list_empty(&qh->qtd_list)
 162                         && ehci->rh_state == EHCI_RH_RUNNING)
 163                 qh_link_async(ehci, qh);
 164         spin_unlock_irqrestore(&ehci->lock, flags);
 165 }
 166
 167 static void ehci_clear_tt_buffer(struct ehci_hcd *ehci, struct ehci_qh *qh,
 168                 struct urb *urb, u32 token)
 169 {
 170
 171         /* If an async split transaction gets an error or is unlinked,
 172          * the TT buffer may be left in an indeterminate state.  We
 173          * have to clear the TT buffer.
 174          *
 175          * Note: this routine is never called for Isochronous transfers.
 176          */
 177         if (urb->dev->tt && !usb_pipeint(urb->pipe) && !qh->clearing_tt) {
 178 #ifdef DEBUG
 179                 struct usb_device *tt = urb->dev->tt->hub;
 180                 dev_dbg(&tt->dev,
 181                         "clear tt buffer port %d, a%d ep%d t%08x\n",
 182                         urb->dev->ttport, urb->dev->devnum,
 183                         usb_pipeendpoint(urb->pipe), token);
 184 #endif /* DEBUG */
 185                 if (!ehci_is_TDI(ehci)
 186                                 || urb->dev->tt->hub !=
 187                                    ehci_to_hcd(ehci)->self.root_hub) {
 188                         if (usb_hub_clear_tt_buffer(urb) == 0)
 189                                 qh->clearing_tt = 1;
 190                 } else {
 191
 192                         /* REVISIT ARC-derived cores don't clear the root
 193                          * hub TT buffer in this way...
 194                          */
 195                 }
 196         }
 197 }
 198
 199 static int qtd_copy_status (
 200         struct ehci_hcd *ehci,
 201         struct urb *urb,
 202         size_t length,
 203         u32 token
 204 )
 205 {
 206         int     status = -EINPROGRESS;
 207
 208         /* count IN/OUT bytes, not SETUP (even short packets) */
 209         if (likely (QTD_PID (token) != 2))
 210                 urb->actual_length += length - QTD_LENGTH (token);
 211
 212         /* don't modify error codes */
 213         if (unlikely(urb->unlinked))
 214                 return status;
 215
 216         /* force cleanup after short read; not always an error */
 217         if (unlikely (IS_SHORT_READ (token)))
 218                 status = -EREMOTEIO;
 219
 220         /* serious "can't proceed" faults reported by the hardware */
 221         if (token & QTD_STS_HALT) {
 222                 if (token & QTD_STS_BABBLE) {
 223                         /* FIXME "must" disable babbling device's port too */
 224                         status = -EOVERFLOW;
 225                 /* CERR nonzero + halt --> stall */
 226                 } else if (QTD_CERR(token)) {
 227                         status = -EPIPE;
 228
 229                 /* In theory, more than one of the following bits can be set
 230                  * since they are sticky and the transaction is retried.
 231                  * Which to test first is rather arbitrary.
 232                  */
 233                 } else if (token & QTD_STS_MMF) {
 234                         /* fs/ls interrupt xfer missed the complete-split */
 235                         status = -EPROTO;
 236                 } else if (token & QTD_STS_DBE) {
 237                         status = (QTD_PID (token) == 1) /* IN ? */
 238                                 ? -ENOSR  /* hc couldn't read data */
 239                                 : -ECOMM; /* hc couldn't write data */
 240                 } else if (token & QTD_STS_XACT) {
 241                         /* timeout, bad CRC, wrong PID, etc */
 242                         ehci_dbg(ehci, "devpath %s ep%d%s 3strikes\n",
 243                                 urb->dev->devpath,
 244                                 usb_pipeendpoint(urb->pipe),
 245                                 usb_pipein(urb->pipe) ? "in" : "out");
 246                         status = -EPROTO;
 247                 } else {        /* unknown */
 248                         status = -EPROTO;
 249                 }
 250
 251                 ehci_vdbg (ehci,
 252                         "dev%d ep%d%s qtd token %08x --> status %d\n",
 253                         usb_pipedevice (urb->pipe),
 254                         usb_pipeendpoint (urb->pipe),
 255                         usb_pipein (urb->pipe) ? "in" : "out",
 256                         token, status);
 257         }
 258
 259         return status;
 260 }
 261
 262 static void
 263 ehci_urb_done(struct ehci_hcd *ehci, struct urb *urb, int status)
 264 __releases(ehci->lock)
 265 __acquires(ehci->lock)
 266 {
 267         if (likely (urb->hcpriv != NULL)) {
 268                 struct ehci_qh  *qh = (struct ehci_qh *) urb->hcpriv;
 269
 270                 /* S-mask in a QH means it's an interrupt urb */
 271                 if ((qh->hw->hw_info2 & cpu_to_hc32(ehci, QH_SMASK)) != 0) {
 272
 273                         /* ... update hc-wide periodic stats (for usbfs) */
 274                         ehci_to_hcd(ehci)->self.bandwidth_int_reqs--;
 275                 }
 276                 qh_put (qh);
 277         }
 278
 279         if (unlikely(urb->unlinked)) {
 280                 COUNT(ehci->stats.unlink);
 281         } else {
 282                 /* report non-error and short read status as zero */
 283                 if (status == -EINPROGRESS || status == -EREMOTEIO)
 284                         status = 0;
 285                 COUNT(ehci->stats.complete);
 286         }
 287
 288 #ifdef EHCI_URB_TRACE
 289         ehci_dbg (ehci,
 290                 "%s %s urb %p ep%d%s status %d len %d/%d\n",
 291                 __func__, urb->dev->devpath, urb,
 292                 usb_pipeendpoint (urb->pipe),
 293                 usb_pipein (urb->pipe) ? "in" : "out",
 294                 status,
 295                 urb->actual_length, urb->transfer_buffer_length);
 296 #endif
 297
 298         /* complete() can reenter this HCD */
 299         usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
 300         spin_unlock (&ehci->lock);
 301         usb_hcd_giveback_urb(ehci_to_hcd(ehci), urb, status);
 302         spin_lock (&ehci->lock);
 303 }
 304
 305 static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh);
 306 static void unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh);
 307
 308 static int qh_schedule (struct ehci_hcd *ehci, struct ehci_qh *qh);
 309
 310 /*
 311  * Process and free completed qtds for a qh, returning URBs to drivers.
 312  * Chases up to qh->hw_current.  Returns number of completions called,
 313  * indicating how much "real" work we did.
 314  */
 315 static unsigned
 316 qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
 317 {
 318         struct ehci_qtd         *last, *end = qh->dummy;
 319         struct list_head        *entry, *tmp;
 320         int                     last_status;
 321         int                     stopped;
 322         unsigned                count = 0;
 323         u8                      state;
 324         struct ehci_qh_hw       *hw = qh->hw;
 325
 326         if (unlikely (list_empty (&qh->qtd_list)))
 327                 return count;
 328
 329         /* completions (or tasks on other cpus) must never clobber HALT
 330          * till we've gone through and cleaned everything up, even when
 331          * they add urbs to this qh's queue or mark them for unlinking.
 332          *
 333          * NOTE:  unlinking expects to be done in queue order.
 334          *
 335          * It's a bug for qh->qh_state to be anything other than
 336          * QH_STATE_IDLE, unless our caller is scan_async() or
 337          * scan_periodic().
 338          */
 339         state = qh->qh_state;
 340         qh->qh_state = QH_STATE_COMPLETING;
 341         stopped = (state == QH_STATE_IDLE);
 342
 343  rescan:
 344         last = NULL;
 345         last_status = -EINPROGRESS;
 346         qh->needs_rescan = 0;
 347
 348         /* remove de-activated QTDs from front of queue.
 349          * after faults (including short reads), cleanup this urb
 350          * then let the queue advance.
 351          * if queue is stopped, handles unlinks.
 352          */
 353         list_for_each_safe (entry, tmp, &qh->qtd_list) {
 354                 struct ehci_qtd *qtd;
 355                 struct urb      *urb;
 356                 u32             token = 0;
 357
 358                 qtd = list_entry (entry, struct ehci_qtd, qtd_list);
 359                 urb = qtd->urb;
 360
 361                 /* clean up any state from previous QTD ...*/
 362                 if (last) {
 363                         if (likely (last->urb != urb)) {
 364                                 ehci_urb_done(ehci, last->urb, last_status);
 365                                 count++;
 366                                 last_status = -EINPROGRESS;
 367                         }
 368                         ehci_qtd_free (ehci, last);
 369                         last = NULL;
 370                 }
 371
 372                 /* ignore urbs submitted during completions we reported */
 373                 if (qtd == end)
 374                         break;
 375
 376                 /* hardware copies qtd out of qh overlay */
 377                 rmb ();
 378                 token = hc32_to_cpu(ehci, qtd->hw_token);
 379
 380                 /* always clean up qtds the hc de-activated */
 381  retry_xacterr:
 382                 if ((token & QTD_STS_ACTIVE) == 0) {
 383
 384                         /* on STALL, error, and short reads this urb must
 385                          * complete and all its qtds must be recycled.
 386                          */
 387                         if ((token & QTD_STS_HALT) != 0) {
 388
 389                                 /* retry transaction errors until we
 390                                  * reach the software xacterr limit
 391                                  */
 392                                 if ((token & QTD_STS_XACT) &&
 393                                                 QTD_CERR(token) == 0 &&
 394                                                 ++qh->xacterrs < QH_XACTERR_MAX &&
 395                                                 !urb->unlinked) {
 396                                         ehci_dbg(ehci,
 397         "detected XactErr len %zu/%zu retry %d\n",
 398         qtd->length - QTD_LENGTH(token), qtd->length, qh->xacterrs);
 399
 400                                         /* reset the token in the qtd and the
 401                                          * qh overlay (which still contains
 402                                          * the qtd) so that we pick up from
 403                                          * where we left off
 404                                          */
 405                                         token &= ~QTD_STS_HALT;
 406                                         token |= QTD_STS_ACTIVE |
 407                                                         (EHCI_TUNE_CERR << 10);
 408                                         qtd->hw_token = cpu_to_hc32(ehci,
 409                                                         token);
 410                                         wmb();
 411                                         hw->hw_token = cpu_to_hc32(ehci,
 412                                                         token);
 413                                         goto retry_xacterr;
 414                                 }
 415                                 stopped = 1;
 416
 417                         /* magic dummy for some short reads; qh won't advance.
 418                          * that silicon quirk can kick in with this dummy too.
 419                          *
 420                          * other short reads won't stop the queue, including
 421                          * control transfers (status stage handles that) or
 422                          * most other single-qtd reads ... the queue stops if
 423                          * URB_SHORT_NOT_OK was set so the driver submitting
 424                          * the urbs could clean it up.
 425                          */
 426                         } else if (IS_SHORT_READ (token)
 427                                         && !(qtd->hw_alt_next
 428                                                 & EHCI_LIST_END(ehci))) {
 429                                 stopped = 1;
 430                         }
 431
 432                 /* stop scanning when we reach qtds the hc is using */
 433                 } else if (likely (!stopped
 434                                 && ehci->rh_state == EHCI_RH_RUNNING)) {
 435                         break;
 436
 437                 /* scan the whole queue for unlinks whenever it stops */
 438                 } else {
 439                         stopped = 1;
 440
 441                         /* cancel everything if we halt, suspend, etc */
 442                         if (ehci->rh_state != EHCI_RH_RUNNING)
 443                                 last_status = -ESHUTDOWN;
 444
 445                         /* this qtd is active; skip it unless a previous qtd
 446                          * for its urb faulted, or its urb was canceled.
 447                          */
 448                         else if (last_status == -EINPROGRESS && !urb->unlinked)
 449                                 continue;
 450
 451                         /* qh unlinked; token in overlay may be most current */
 452                         if (state == QH_STATE_IDLE
 453                                         && cpu_to_hc32(ehci, qtd->qtd_dma)
 454                                                 == hw->hw_current) {
 455                                 token = hc32_to_cpu(ehci, hw->hw_token);
 456
 457                                 /* An unlink may leave an incomplete
 458                                  * async transaction in the TT buffer.
 459                                  * We have to clear it.
 460                                  */
 461                                 ehci_clear_tt_buffer(ehci, qh, urb, token);
 462                         }
 463                 }
 464
 465                 /* unless we already know the urb's status, collect qtd status
 466                  * and update count of bytes transferred.  in common short read
 467                  * cases with only one data qtd (including control transfers),
 468                  * queue processing won't halt.  but with two or more qtds (for
 469                  * example, with a 32 KB transfer), when the first qtd gets a
 470                  * short read the second must be removed by hand.
 471                  */
 472                 if (last_status == -EINPROGRESS) {
 473                         last_status = qtd_copy_status(ehci, urb,
 474                                         qtd->length, token);
 475                         if (last_status == -EREMOTEIO
 476                                         && (qtd->hw_alt_next
 477                                                 & EHCI_LIST_END(ehci)))
 478                                 last_status = -EINPROGRESS;
 479
 480                         /* As part of low/full-speed endpoint-halt processing
 481                          * we must clear the TT buffer (11.17.5).
 482                          */
 483                         if (unlikely(last_status != -EINPROGRESS &&
 484                                         last_status != -EREMOTEIO)) {
 485                                 /* The TT's in some hubs malfunction when they
 486                                  * receive this request following a STALL (they
 487                                  * stop sending isochronous packets).  Since a
 488                                  * STALL can't leave the TT buffer in a busy
 489                                  * state (if you believe Figures 11-48 - 11-51
 490                                  * in the USB 2.0 spec), we won't clear the TT
 491                                  * buffer in this case.  Strictly speaking this
 492                                  * is a violation of the spec.
 493                                  */
 494                                 if (last_status != -EPIPE)
 495                                         ehci_clear_tt_buffer(ehci, qh, urb,
 496                                                         token);
 497                         }
 498                 }
 499
 500                 /* if we're removing something not at the queue head,
 501                  * patch the hardware queue pointer.
 502                  */
 503                 if (stopped && qtd->qtd_list.prev != &qh->qtd_list) {
 504                         last = list_entry (qtd->qtd_list.prev,
 505                                         struct ehci_qtd, qtd_list);
 506                         last->hw_next = qtd->hw_next;
 507                 }
 508
 509                 /* remove qtd; it's recycled after possible urb completion */
 510                 list_del (&qtd->qtd_list);
 511                 last = qtd;
 512
 513                 /* reinit the xacterr counter for the next qtd */
 514                 qh->xacterrs = 0;
 515         }
 516
 517         /* last urb's completion might still need calling */
 518         if (likely (last != NULL)) {
 519                 ehci_urb_done(ehci, last->urb, last_status);
 520                 count++;
 521                 ehci_qtd_free (ehci, last);
 522         }
 523
 524         /* Do we need to rescan for URBs dequeued during a giveback? */
 525         if (unlikely(qh->needs_rescan)) {
 526                 /* If the QH is already unlinked, do the rescan now. */
 527                 if (state == QH_STATE_IDLE)
 528                         goto rescan;
 529
 530                 /* Otherwise we have to wait until the QH is fully unlinked.
 531                  * Our caller will start an unlink if qh->needs_rescan is
 532                  * set.  But if an unlink has already started, nothing needs
 533                  * to be done.
 534                  */
 535                 if (state != QH_STATE_LINKED)
 536                         qh->needs_rescan = 0;
 537         }
 538
 539         /* restore original state; caller must unlink or relink */
 540         qh->qh_state = state;
 541
 542         /* be sure the hardware's done with the qh before refreshing
 543          * it after fault cleanup, or recovering from silicon wrongly
 544          * overlaying the dummy qtd (which reduces DMA chatter).
 545          */
 546         if (stopped != 0 || hw->hw_qtd_next == EHCI_LIST_END(ehci)) {
 547                 switch (state) {
 548                 case QH_STATE_IDLE:
 549                         qh_refresh(ehci, qh);
 550                         break;
 551                 case QH_STATE_LINKED:
 552                         /* We won't refresh a QH that's linked (after the HC
 553                          * stopped the queue).  That avoids a race:
 554                          *  - HC reads first part of QH;
 555                          *  - CPU updates that first part and the token;
 556                          *  - HC reads rest of that QH, including token
 557                          * Result:  HC gets an inconsistent image, and then
 558                          * DMAs to/from the wrong memory (corrupting it).
 559                          *
 560                          * That should be rare for interrupt transfers,
 561                          * except maybe high bandwidth ...
 562                          */
 563
 564                         /* Tell the caller to start an unlink */
 565                         qh->needs_rescan = 1;
 566                         break;
 567                 /* otherwise, unlink already started */
 568                 }
 569         }
 570
 571         return count;
 572 }
 573
 574 /*-------------------------------------------------------------------------*/
 575
 576 // high bandwidth multiplier, as encoded in highspeed endpoint descriptors
 577 #define hb_mult(wMaxPacketSize) (1 + (((wMaxPacketSize) >> 11) & 0x03))
 578 // ... and packet size, for any kind of endpoint descriptor
 579 #define max_packet(wMaxPacketSize) ((wMaxPacketSize) & 0x07ff)
 580
 581 /*
 582  * reverse of qh_urb_transaction:  free a list of TDs.
 583  * used for cleanup after errors, before HC sees an URB's TDs.
 584  */
 585 static void qtd_list_free (
 586         struct ehci_hcd         *ehci,
 587         struct urb              *urb,
 588         struct list_head        *qtd_list
 589 ) {
 590         struct list_head        *entry, *temp;
 591
 592         list_for_each_safe (entry, temp, qtd_list) {
 593                 struct ehci_qtd *qtd;
 594
 595                 qtd = list_entry (entry, struct ehci_qtd, qtd_list);
 596                 list_del (&qtd->qtd_list);
 597                 ehci_qtd_free (ehci, qtd);
 598         }
 599 }
 600
 601 /*
 602  * create a list of filled qtds for this URB; won't link into qh.
 603  */
 604 static struct list_head *
 605 qh_urb_transaction (
 606         struct ehci_hcd         *ehci,
 607         struct urb              *urb,
 608         struct list_head        *head,
 609         gfp_t                   flags
 610 ) {
 611         struct ehci_qtd         *qtd, *qtd_prev;
 612         dma_addr_t              buf;
 613         int                     len, this_sg_len, maxpacket;
 614         int                     is_input;
 615         u32                     token;
 616         int                     i;
 617         struct scatterlist      *sg;
 618
 619         /*
 620          * URBs map to sequences of QTDs:  one logical transaction
 621          */
 622         qtd = ehci_qtd_alloc (ehci, flags);
 623         if (unlikely (!qtd))
 624                 return NULL;
 625         list_add_tail (&qtd->qtd_list, head);
 626         qtd->urb = urb;
 627
 628         token = QTD_STS_ACTIVE;
 629         token |= (EHCI_TUNE_CERR << 10);
 630         /* for split transactions, SplitXState initialized to zero */
 631
 632         len = urb->transfer_buffer_length;
 633         is_input = usb_pipein (urb->pipe);
 634         if (usb_pipecontrol (urb->pipe)) {
 635                 /* SETUP pid */
 636                 qtd_fill(ehci, qtd, urb->setup_dma,
 637                                 sizeof (struct usb_ctrlrequest),
 638                                 token | (2 /* "setup" */ << 8), 8);
 639
 640                 /* ... and always at least one more pid */
 641                 token ^= QTD_TOGGLE;
 642                 qtd_prev = qtd;
 643                 qtd = ehci_qtd_alloc (ehci, flags);
 644                 if (unlikely (!qtd))
 645                         goto cleanup;
 646                 qtd->urb = urb;
 647                 qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 648                 list_add_tail (&qtd->qtd_list, head);
 649
 650                 /* for zero length DATA stages, STATUS is always IN */
 651                 if (len == 0)
 652                         token |= (1 /* "in" */ << 8);
 653         }
 654
 655         /*
 656          * data transfer stage:  buffer setup
 657          */
 658         i = urb->num_mapped_sgs;
 659         if (len > 0 && i > 0) {
 660                 sg = urb->sg;
 661                 buf = sg_dma_address(sg);
 662
 663                 /* urb->transfer_buffer_length may be smaller than the
 664                  * size of the scatterlist (or vice versa)
 665                  */
 666                 this_sg_len = min_t(int, sg_dma_len(sg), len);
 667         } else {
 668                 sg = NULL;
 669                 buf = urb->transfer_dma;
 670                 this_sg_len = len;
 671         }
 672
 673         if (is_input)
 674                 token |= (1 /* "in" */ << 8);
 675         /* else it's already initted to "out" pid (0 << 8) */
 676
 677         maxpacket = max_packet(usb_maxpacket(urb->dev, urb->pipe, !is_input));
 678
 679         /*
 680          * buffer gets wrapped in one or more qtds;
 681          * last one may be "short" (including zero len)
 682          * and may serve as a control status ack
 683          */
 684         for (;;) {
 685                 int this_qtd_len;
 686
 687                 this_qtd_len = qtd_fill(ehci, qtd, buf, this_sg_len, token,
 688                                 maxpacket);
 689                 this_sg_len -= this_qtd_len;
 690                 len -= this_qtd_len;
 691                 buf += this_qtd_len;
 692
 693                 /*
 694                  * short reads advance to a "magic" dummy instead of the next
 695                  * qtd ... that forces the queue to stop, for manual cleanup.
 696                  * (this will usually be overridden later.)
 697                  */
 698                 if (is_input)
 699                         qtd->hw_alt_next = ehci->async->hw->hw_alt_next;
 700
 701                 /* qh makes control packets use qtd toggle; maybe switch it */
 702                 if ((maxpacket & (this_qtd_len + (maxpacket - 1))) == 0)
 703                         token ^= QTD_TOGGLE;
 704
 705                 if (likely(this_sg_len <= 0)) {
 706                         if (--i <= 0 || len <= 0)
 707                                 break;
 708                         sg = sg_next(sg);
 709                         buf = sg_dma_address(sg);
 710                         this_sg_len = min_t(int, sg_dma_len(sg), len);
 711                 }
 712
 713                 qtd_prev = qtd;
 714                 qtd = ehci_qtd_alloc (ehci, flags);
 715                 if (unlikely (!qtd))
 716                         goto cleanup;
 717                 qtd->urb = urb;
 718                 qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 719                 list_add_tail (&qtd->qtd_list, head);
 720         }
 721
 722         /*
 723          * unless the caller requires manual cleanup after short reads,
 724          * have the alt_next mechanism keep the queue running after the
 725          * last data qtd (the only one, for control and most other cases).
 726          */
 727         if (likely ((urb->transfer_flags & URB_SHORT_NOT_OK) == 0
 728                                 || usb_pipecontrol (urb->pipe)))
 729                 qtd->hw_alt_next = EHCI_LIST_END(ehci);
 730
 731         /*
 732          * control requests may need a terminating data "status" ack;
 733          * other OUT ones may need a terminating short packet
 734          * (zero length).
 735          */
 736         if (likely (urb->transfer_buffer_length != 0)) {
 737                 int     one_more = 0;
 738
 739                 if (usb_pipecontrol (urb->pipe)) {
 740                         one_more = 1;
 741                         token ^= 0x0100;        /* "in" <--> "out"  */
 742                         token |= QTD_TOGGLE;    /* force DATA1 */
 743                 } else if (usb_pipeout(urb->pipe)
 744                                 && (urb->transfer_flags & URB_ZERO_PACKET)
 745                                 && !(urb->transfer_buffer_length % maxpacket)) {
 746                         one_more = 1;
 747                 }
 748                 if (one_more) {
 749                         qtd_prev = qtd;
 750                         qtd = ehci_qtd_alloc (ehci, flags);
 751                         if (unlikely (!qtd))
 752                                 goto cleanup;
 753                         qtd->urb = urb;
 754                         qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 755                         list_add_tail (&qtd->qtd_list, head);
 756
 757                         /* never any data in such packets */
 758                         qtd_fill(ehci, qtd, 0, 0, token, 0);
 759                 }
 760         }
 761
 762         /* by default, enable interrupt on urb completion */
 763         if (likely (!(urb->transfer_flags & URB_NO_INTERRUPT)))
 764                 qtd->hw_token |= cpu_to_hc32(ehci, QTD_IOC);
 765         return head;
 766
 767 cleanup:
 768         qtd_list_free (ehci, urb, head);
 769         return NULL;
 770 }
 771
 772 /*-------------------------------------------------------------------------*/
 773
 774 // Would be best to create all qh's from config descriptors,
 775 // when each interface/altsetting is established.  Unlink
 776 // any previous qh and cancel its urbs first; endpoints are
 777 // implicitly reset then (data toggle too).
 778 // That'd mean updating how usbcore talks to HCDs. (2.7?)
 779
 780
 781 /*
 782  * Each QH holds a qtd list; a QH is used for everything except iso.
 783  *
 784  * For interrupt urbs, the scheduler must set the microframe scheduling
 785  * mask(s) each time the QH gets scheduled.  For highspeed, that's
 786  * just one microframe in the s-mask.  For split interrupt transactions
 787  * there are additional complications: c-mask, maybe FSTNs.
 788  */
 789 static struct ehci_qh *
 790 qh_make (
 791         struct ehci_hcd         *ehci,
 792         struct urb              *urb,
 793         gfp_t                   flags
 794 ) {
 795         struct ehci_qh          *qh = ehci_qh_alloc (ehci, flags);
 796         u32                     info1 = 0, info2 = 0;
 797         int                     is_input, type;
 798         int                     maxp = 0;
 799         struct usb_tt           *tt = urb->dev->tt;
 800         struct ehci_qh_hw       *hw;
 801
 802         if (!qh)
 803                 return qh;
 804
 805         /*
 806          * init endpoint/device data for this QH
 807          */
 808         info1 |= usb_pipeendpoint (urb->pipe) << 8;
 809         info1 |= usb_pipedevice (urb->pipe) << 0;
 810
 811         is_input = usb_pipein (urb->pipe);
 812         type = usb_pipetype (urb->pipe);
 813         maxp = usb_maxpacket (urb->dev, urb->pipe, !is_input);
 814
 815         /* 1024 byte maxpacket is a hardware ceiling.  High bandwidth
 816          * acts like up to 3KB, but is built from smaller packets.
 817          */
 818         if (max_packet(maxp) > 1024) {
 819                 ehci_dbg(ehci, "bogus qh maxpacket %d\n", max_packet(maxp));
 820                 goto done;
 821         }
 822
 823         /* Compute interrupt scheduling parameters just once, and save.
 824          * - allowing for high bandwidth, how many nsec/uframe are used?
 825          * - split transactions need a second CSPLIT uframe; same question
 826          * - splits also need a schedule gap (for full/low speed I/O)
 827          * - qh has a polling interval
 828          *
 829          * For control/bulk requests, the HC or TT handles these.
 830          */
 831         if (type == PIPE_INTERRUPT) {
 832                 qh->usecs = NS_TO_US(usb_calc_bus_time(USB_SPEED_HIGH,
 833                                 is_input, 0,
 834                                 hb_mult(maxp) * max_packet(maxp)));
 835                 qh->start = NO_FRAME;
 836                 qh->stamp = ehci->periodic_stamp;
 837
 838                 if (urb->dev->speed == USB_SPEED_HIGH) {
 839                         qh->c_usecs = 0;
 840                         qh->gap_uf = 0;
 841
 842                         qh->period = urb->interval >> 3;
 843                         if (qh->period == 0 && urb->interval != 1) {
 844                                 /* NOTE interval 2 or 4 uframes could work.
 845                                  * But interval 1 scheduling is simpler, and
 846                                  * includes high bandwidth.
 847                                  */
 848                                 urb->interval = 1;
 849                         } else if (qh->period > ehci->periodic_size) {
 850                                 qh->period = ehci->periodic_size;
 851                                 urb->interval = qh->period << 3;
 852                         }
 853                 } else {
 854                         int             think_time;
 855
 856                         /* gap is f(FS/LS transfer times) */
 857                         qh->gap_uf = 1 + usb_calc_bus_time (urb->dev->speed,
 858                                         is_input, 0, maxp) / (125 * 1000);
 859
 860                         /* FIXME this just approximates SPLIT/CSPLIT times */
 861                         if (is_input) {         // SPLIT, gap, CSPLIT+DATA
 862                                 qh->c_usecs = qh->usecs + HS_USECS (0);
 863                                 qh->usecs = HS_USECS (1);
 864                         } else {                // SPLIT+DATA, gap, CSPLIT
 865                                 qh->usecs += HS_USECS (1);
 866                                 qh->c_usecs = HS_USECS (0);
 867                         }
 868
 869                         think_time = tt ? tt->think_time : 0;
 870                         qh->tt_usecs = NS_TO_US (think_time +
 871                                         usb_calc_bus_time (urb->dev->speed,
 872                                         is_input, 0, max_packet (maxp)));
 873                         qh->period = urb->interval;
 874                         if (qh->period > ehci->periodic_size) {
 875                                 qh->period = ehci->periodic_size;
 876                                 urb->interval = qh->period;
 877                         }
 878                 }
 879         }
 880
 881         /* support for tt scheduling, and access to toggles */
 882         qh->dev = urb->dev;
 883
 884         /* using TT? */
 885         switch (urb->dev->speed) {
 886         case USB_SPEED_LOW:
 887                 info1 |= (1 << 12);     /* EPS "low" */
 888                 /* FALL THROUGH */
 889
 890         case USB_SPEED_FULL:
 891                 /* EPS 0 means "full" */
 892                 if (type != PIPE_INTERRUPT)
 893                         info1 |= (EHCI_TUNE_RL_TT << 28);
 894                 if (type == PIPE_CONTROL) {
 895                         info1 |= (1 << 27);     /* for TT */
 896                         info1 |= 1 << 14;       /* toggle from qtd */
 897                 }
 898                 info1 |= maxp << 16;
 899
 900                 info2 |= (EHCI_TUNE_MULT_TT << 30);
 901
 902                 /* Some Freescale processors have an erratum in which the
 903                  * port number in the queue head was 0..N-1 instead of 1..N.
 904                  */
 905                 if (ehci_has_fsl_portno_bug(ehci))
 906                         info2 |= (urb->dev->ttport-1) << 23;
 907                 else
 908                         info2 |= urb->dev->ttport << 23;
 909
 910                 /* set the address of the TT; for TDI's integrated
 911                  * root hub tt, leave it zeroed.
 912                  */
 913                 if (tt && tt->hub != ehci_to_hcd(ehci)->self.root_hub)
 914                         info2 |= tt->hub->devnum << 16;
 915
 916                 /* NOTE:  if (PIPE_INTERRUPT) { scheduler sets c-mask } */
 917
 918                 break;
 919
 920         case USB_SPEED_HIGH:            /* no TT involved */
 921                 info1 |= (2 << 12);     /* EPS "high" */
 922                 if (type == PIPE_CONTROL) {
 923                         info1 |= (EHCI_TUNE_RL_HS << 28);
 924                         info1 |= 64 << 16;      /* usb2 fixed maxpacket */
 925                         info1 |= 1 << 14;       /* toggle from qtd */
 926                         info2 |= (EHCI_TUNE_MULT_HS << 30);
 927                 } else if (type == PIPE_BULK) {
 928                         info1 |= (EHCI_TUNE_RL_HS << 28);
 929                         /* The USB spec says that high speed bulk endpoints
 930                          * always use 512 byte maxpacket.  But some device
 931                          * vendors decided to ignore that, and MSFT is happy
 932                          * to help them do so.  So now people expect to use
 933                          * such nonconformant devices with Linux too; sigh.
 934                          */
 935                         info1 |= max_packet(maxp) << 16;
 936                         info2 |= (EHCI_TUNE_MULT_HS << 30);
 937                 } else {                /* PIPE_INTERRUPT */
 938                         info1 |= max_packet (maxp) << 16;
 939                         info2 |= hb_mult (maxp) << 30;
 940                 }
 941                 break;
 942         default:
 943                 dbg ("bogus dev %p speed %d", urb->dev, urb->dev->speed);
 944 done:
 945                 qh_put (qh);
 946                 return NULL;
 947         }
 948
 949         /* NOTE:  if (PIPE_INTERRUPT) { scheduler sets s-mask } */
 950
 951         /* init as live, toggle clear, advance to dummy */
 952         qh->qh_state = QH_STATE_IDLE;
 953         hw = qh->hw;
 954         hw->hw_info1 = cpu_to_hc32(ehci, info1);
 955         hw->hw_info2 = cpu_to_hc32(ehci, info2);
 956         qh->is_out = !is_input;
 957         usb_settoggle (urb->dev, usb_pipeendpoint (urb->pipe), !is_input, 1);
 958         qh_refresh (ehci, qh);
 959         return qh;
 960 }
 961
 962 /*-------------------------------------------------------------------------*/
 963
 964 /* move qh (and its qtds) onto async queue; maybe enable queue.  */
 965
 966 static void qh_link_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 967 {
 968         __hc32          dma = QH_NEXT(ehci, qh->qh_dma);
 969         struct ehci_qh  *head;
 970
 971         /* Don't link a QH if there's a Clear-TT-Buffer pending */
 972         if (unlikely(qh->clearing_tt))
 973                 return;
 974
 975         WARN_ON(qh->qh_state != QH_STATE_IDLE);
 976
 977         /* (re)start the async schedule? */
 978         head = ehci->async;
 979         timer_action_done (ehci, TIMER_ASYNC_OFF);
 980         if (!head->qh_next.qh) {
 981                 u32     cmd = ehci_readl(ehci, &ehci->regs->command);
 982
 983                 if (!(cmd & CMD_ASE)) {
 984                         /* in case a clear of CMD_ASE didn't take yet */
 985                         (void)handshake(ehci, &ehci->regs->status,
 986                                         STS_ASS, 0, 150);
 987                         cmd |= CMD_ASE;
 988                         ehci_writel(ehci, cmd, &ehci->regs->command);
 989                         /* posted write need not be known to HC yet ... */
 990                 }
 991         }
 992
 993         /* clear halt and/or toggle; and maybe recover from silicon quirk */
 994         qh_refresh(ehci, qh);
 995
 996         /* splice right after start */
 997         qh->qh_next = head->qh_next;
 998         qh->hw->hw_next = head->hw->hw_next;
 999         wmb ();
1000
1001         head->qh_next.qh = qh;
1002         head->hw->hw_next = dma;
1003
1004         qh_get(qh);
1005         qh->xacterrs = 0;
1006         qh->qh_state = QH_STATE_LINKED;
1007         /* qtd completions reported later by interrupt */
1008 }
1009
1010 /*-------------------------------------------------------------------------*/
1011
1012 /*
1013  * For control/bulk/interrupt, return QH with these TDs appended.
1014  * Allocates and initializes the QH if necessary.
1015  * Returns null if it can't allocate a QH it needs to.
1016  * If the QH has TDs (urbs) already, that's great.
1017  */
1018 static struct ehci_qh *qh_append_tds (
1019         struct ehci_hcd         *ehci,
1020         struct urb              *urb,
1021         struct list_head        *qtd_list,
1022         int                     epnum,
1023         void                    **ptr
1024 )
1025 {
1026         struct ehci_qh          *qh = NULL;
1027         __hc32                  qh_addr_mask = cpu_to_hc32(ehci, 0x7f);
1028
1029         qh = (struct ehci_qh *) *ptr;
1030         if (unlikely (qh == NULL)) {
1031                 /* can't sleep here, we have ehci->lock... */
1032                 qh = qh_make (ehci, urb, GFP_ATOMIC);
1033                 *ptr = qh;
1034         }
1035         if (likely (qh != NULL)) {
1036                 struct ehci_qtd *qtd;
1037
1038                 if (unlikely (list_empty (qtd_list)))
1039                         qtd = NULL;
1040                 else
1041                         qtd = list_entry (qtd_list->next, struct ehci_qtd,
1042                                         qtd_list);
1043
1044                 /* control qh may need patching ... */
1045                 if (unlikely (epnum == 0)) {
1046
1047                         /* usb_reset_device() briefly reverts to address 0 */
1048                         if (usb_pipedevice (urb->pipe) == 0)
1049                                 qh->hw->hw_info1 &= ~qh_addr_mask;
1050                 }
1051
1052                 /* just one way to queue requests: swap with the dummy qtd.
1053                  * only hc or qh_refresh() ever modify the overlay.
1054                  */
1055                 if (likely (qtd != NULL)) {
1056                         struct ehci_qtd         *dummy;
1057                         dma_addr_t              dma;
1058                         __hc32                  token;
1059
1060                         /* to avoid racing the HC, use the dummy td instead of
1061                          * the first td of our list (becomes new dummy).  both
1062                          * tds stay deactivated until we're done, when the
1063                          * HC is allowed to fetch the old dummy (4.10.2).
1064                          */
1065                         token = qtd->hw_token;
1066                         qtd->hw_token = HALT_BIT(ehci);
1067
1068                         dummy = qh->dummy;
1069
1070                         dma = dummy->qtd_dma;
1071                         *dummy = *qtd;
1072                         dummy->qtd_dma = dma;
1073
1074                         list_del (&qtd->qtd_list);
1075                         list_add (&dummy->qtd_list, qtd_list);
1076                         list_splice_tail(qtd_list, &qh->qtd_list);
1077
1078                         ehci_qtd_init(ehci, qtd, qtd->qtd_dma);
1079                         qh->dummy = qtd;
1080
1081                         /* hc must see the new dummy at list end */
1082                         dma = qtd->qtd_dma;
1083                         qtd = list_entry (qh->qtd_list.prev,
1084                                         struct ehci_qtd, qtd_list);
1085                         qtd->hw_next = QTD_NEXT(ehci, dma);
1086
1087                         /* let the hc process these next qtds */
1088                         wmb ();
1089                         dummy->hw_token = token;
1090
1091                         urb->hcpriv = qh_get (qh);
1092                 }
1093         }
1094         return qh;
1095 }
1096
1097 /*-------------------------------------------------------------------------*/
1098
1099 static int
1100 submit_async (
1101         struct ehci_hcd         *ehci,
1102         struct urb              *urb,
1103         struct list_head        *qtd_list,
1104         gfp_t                   mem_flags
1105 ) {
1106         int                     epnum;
1107         unsigned long           flags;
1108         struct ehci_qh          *qh = NULL;
1109         int                     rc;
1110
1111         epnum = urb->ep->desc.bEndpointAddress;
1112
1113 #ifdef EHCI_URB_TRACE
1114         {
1115                 struct ehci_qtd *qtd;
1116                 qtd = list_entry(qtd_list->next, struct ehci_qtd, qtd_list);
1117                 ehci_dbg(ehci,
1118                          "%s %s urb %p ep%d%s len %d, qtd %p [qh %p]\n",
1119                          __func__, urb->dev->devpath, urb,
1120                          epnum & 0x0f, (epnum & USB_DIR_IN) ? "in" : "out",
1121                          urb->transfer_buffer_length,
1122                          qtd, urb->ep->hcpriv);
1123         }
1124 #endif
1125
1126         spin_lock_irqsave (&ehci->lock, flags);
1127         if (unlikely(!HCD_HW_ACCESSIBLE(ehci_to_hcd(ehci)))) {
1128                 rc = -ESHUTDOWN;
1129                 goto done;
1130         }
1131         rc = usb_hcd_link_urb_to_ep(ehci_to_hcd(ehci), urb);
1132         if (unlikely(rc))
1133                 goto done;
1134
1135         qh = qh_append_tds(ehci, urb, qtd_list, epnum, &urb->ep->hcpriv);
1136         if (unlikely(qh == NULL)) {
1137                 usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
1138                 rc = -ENOMEM;
1139                 goto done;
1140         }
1141
1142         /* Control/bulk operations through TTs don't need scheduling,
1143          * the HC and TT handle it when the TT has a buffer ready.
1144          */
1145         if (likely (qh->qh_state == QH_STATE_IDLE))
1146                 qh_link_async(ehci, qh);
1147  done:
1148         spin_unlock_irqrestore (&ehci->lock, flags);
1149         if (unlikely (qh == NULL))
1150                 qtd_list_free (ehci, urb, qtd_list);
1151         return rc;
1152 }
1153
1154 /*-------------------------------------------------------------------------*/
1155
1156 /* the async qh for the qtds being reclaimed are now unlinked from the HC */
1157
1158 static void end_unlink_async (struct ehci_hcd *ehci)
1159 {
1160         struct ehci_qh          *qh = ehci->reclaim;
1161         struct ehci_qh          *next;
1162
1163         iaa_watchdog_done(ehci);
1164
1165         // qh->hw_next = cpu_to_hc32(qh->qh_dma);
1166         qh->qh_state = QH_STATE_IDLE;
1167         qh->qh_next.qh = NULL;
1168         qh_put (qh);                    // refcount from reclaim
1169
1170         /* other unlink(s) may be pending (in QH_STATE_UNLINK_WAIT) */
1171         next = qh->reclaim;
1172         ehci->reclaim = next;
1173         qh->reclaim = NULL;
1174
1175         qh_completions (ehci, qh);
1176
1177         if (!list_empty(&qh->qtd_list) && ehci->rh_state == EHCI_RH_RUNNING) {
1178                 qh_link_async (ehci, qh);
1179         } else {
1180                 /* it's not free to turn the async schedule on/off; leave it
1181                  * active but idle for a while once it empties.
1182                  */
1183                 if (ehci->rh_state == EHCI_RH_RUNNING
1184                                 && ehci->async->qh_next.qh == NULL)
1185                         timer_action (ehci, TIMER_ASYNC_OFF);
1186         }
1187         qh_put(qh);                     /* refcount from async list */
1188
1189         if (next) {
1190                 ehci->reclaim = NULL;
1191                 start_unlink_async (ehci, next);
1192         }
1193
1194         if (ehci->has_synopsys_hc_bug)
1195                 ehci_writel(ehci, (u32) ehci->async->qh_dma,
1196                             &ehci->regs->async_next);
1197 }
1198
1199 /* makes sure the async qh will become idle */
1200 /* caller must own ehci->lock */
1201
1202 static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
1203 {
1204         int             cmd = ehci_readl(ehci, &ehci->regs->command);
1205         struct ehci_qh  *prev;
1206
1207 #ifdef DEBUG
1208         assert_spin_locked(&ehci->lock);
1209         if (ehci->reclaim
1210                         || (qh->qh_state != QH_STATE_LINKED
1211                                 && qh->qh_state != QH_STATE_UNLINK_WAIT)
1212                         )
1213                 BUG ();
1214 #endif
1215
1216         /* stop async schedule right now? */
1217         if (unlikely (qh == ehci->async)) {
1218                 /* can't get here without STS_ASS set */
1219                 if (ehci->rh_state != EHCI_RH_HALTED
1220                                 && !ehci->reclaim) {
1221                         /* ... and CMD_IAAD clear */
1222                         ehci_writel(ehci, cmd & ~CMD_ASE,
1223                                     &ehci->regs->command);
1224                         wmb ();
1225                         // handshake later, if we need to
1226                         timer_action_done (ehci, TIMER_ASYNC_OFF);
1227                 }
1228                 return;
1229         }
1230
1231         qh->qh_state = QH_STATE_UNLINK;
1232         ehci->reclaim = qh = qh_get (qh);
1233
1234         prev = ehci->async;
1235         while (prev->qh_next.qh != qh)
1236                 prev = prev->qh_next.qh;
1237
1238         prev->hw->hw_next = qh->hw->hw_next;
1239         prev->qh_next = qh->qh_next;
1240         if (ehci->qh_scan_next == qh)
1241                 ehci->qh_scan_next = qh->qh_next.qh;
1242         wmb ();
1243
1244         /* If the controller isn't running, we don't have to wait for it */
1245         if (unlikely(ehci->rh_state != EHCI_RH_RUNNING)) {
1246                 /* if (unlikely (qh->reclaim != 0))
1247                  *      this will recurse, probably not much
1248                  */
1249                 end_unlink_async (ehci);
1250                 return;
1251         }
1252
1253         cmd |= CMD_IAAD;
1254         ehci_writel(ehci, cmd, &ehci->regs->command);
1255         (void)ehci_readl(ehci, &ehci->regs->command);
1256         iaa_watchdog_start(ehci);
1257 }
1258
1259 /*-------------------------------------------------------------------------*/
1260
1261 static void scan_async (struct ehci_hcd *ehci)
1262 {
1263         bool                    stopped;
1264         struct ehci_qh          *qh;
1265         enum ehci_timer_action  action = TIMER_IO_WATCHDOG;
1266
1267         timer_action_done (ehci, TIMER_ASYNC_SHRINK);
1268         stopped = (ehci->rh_state != EHCI_RH_RUNNING);
1269
1270         ehci->qh_scan_next = ehci->async->qh_next.qh;
1271         while (ehci->qh_scan_next) {
1272                 qh = ehci->qh_scan_next;
1273                 ehci->qh_scan_next = qh->qh_next.qh;
1274  rescan:
1275                 /* clean any finished work for this qh */
1276                 if (!list_empty(&qh->qtd_list)) {
1277                         int temp;
1278
1279                         /*
1280                          * Unlinks could happen here; completion reporting
1281                          * drops the lock.  That's why ehci->qh_scan_next
1282                          * always holds the next qh to scan; if the next qh
1283                          * gets unlinked then ehci->qh_scan_next is adjusted
1284                          * in start_unlink_async().
1285                          */
1286                         qh = qh_get(qh);
1287                         temp = qh_completions(ehci, qh);
1288                         if (qh->needs_rescan)
1289                                 unlink_async(ehci, qh);
1290                         qh->unlink_time = jiffies + EHCI_SHRINK_JIFFIES;
1291                         qh_put(qh);
1292                         if (temp != 0)
1293                                 goto rescan;
1294                 }
1295
1296                 /* unlink idle entries, reducing DMA usage as well
1297                  * as HCD schedule-scanning costs.  delay for any qh
1298                  * we just scanned, there's a not-unusual case that it
1299                  * doesn't stay idle for long.
1300                  * (plus, avoids some kind of re-activation race.)
1301                  */
1302                 if (list_empty(&qh->qtd_list)
1303                                 && qh->qh_state == QH_STATE_LINKED) {
1304                         if (!ehci->reclaim && (stopped ||
1305                                         time_after_eq(jiffies, qh->unlink_time)))
1306                                 start_unlink_async(ehci, qh);
1307                         else
1308                                 action = TIMER_ASYNC_SHRINK;
1309                 }
1310         }
1311         if (action == TIMER_ASYNC_SHRINK)
1312                 timer_action (ehci, TIMER_ASYNC_SHRINK);
1313 }