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