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, QH_TOGGLE_CTL))) {
 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 (unlikely(urb->unlinked)) {
 273                 COUNT(ehci->stats.unlink);
 274         } else {
 275                 /* report non-error and short read status as zero */
 276                 if (status == -EINPROGRESS || status == -EREMOTEIO)
 277                         status = 0;
 278                 COUNT(ehci->stats.complete);
 279         }
 280
 281 #ifdef EHCI_URB_TRACE
 282         ehci_dbg (ehci,
 283                 "%s %s urb %p ep%d%s status %d len %d/%d\n",
 284                 __func__, urb->dev->devpath, urb,
 285                 usb_pipeendpoint (urb->pipe),
 286                 usb_pipein (urb->pipe) ? "in" : "out",
 287                 status,
 288                 urb->actual_length, urb->transfer_buffer_length);
 289 #endif
 290
 291         /* complete() can reenter this HCD */
 292         usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
 293         spin_unlock (&ehci->lock);
 294         usb_hcd_giveback_urb(ehci_to_hcd(ehci), urb, status);
 295         spin_lock (&ehci->lock);
 296 }
 297
 298 static int qh_schedule (struct ehci_hcd *ehci, struct ehci_qh *qh);
 299
 300 /*
 301  * Process and free completed qtds for a qh, returning URBs to drivers.
 302  * Chases up to qh->hw_current.  Returns number of completions called,
 303  * indicating how much "real" work we did.
 304  */
 305 static unsigned
 306 qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
 307 {
 308         struct ehci_qtd         *last, *end = qh->dummy;
 309         struct list_head        *entry, *tmp;
 310         int                     last_status;
 311         int                     stopped;
 312         unsigned                count = 0;
 313         u8                      state;
 314         struct ehci_qh_hw       *hw = qh->hw;
 315
 316         if (unlikely (list_empty (&qh->qtd_list)))
 317                 return count;
 318
 319         /* completions (or tasks on other cpus) must never clobber HALT
 320          * till we've gone through and cleaned everything up, even when
 321          * they add urbs to this qh's queue or mark them for unlinking.
 322          *
 323          * NOTE:  unlinking expects to be done in queue order.
 324          *
 325          * It's a bug for qh->qh_state to be anything other than
 326          * QH_STATE_IDLE, unless our caller is scan_async() or
 327          * scan_intr().
 328          */
 329         state = qh->qh_state;
 330         qh->qh_state = QH_STATE_COMPLETING;
 331         stopped = (state == QH_STATE_IDLE);
 332
 333  rescan:
 334         last = NULL;
 335         last_status = -EINPROGRESS;
 336         qh->needs_rescan = 0;
 337
 338         /* remove de-activated QTDs from front of queue.
 339          * after faults (including short reads), cleanup this urb
 340          * then let the queue advance.
 341          * if queue is stopped, handles unlinks.
 342          */
 343         list_for_each_safe (entry, tmp, &qh->qtd_list) {
 344                 struct ehci_qtd *qtd;
 345                 struct urb      *urb;
 346                 u32             token = 0;
 347
 348                 qtd = list_entry (entry, struct ehci_qtd, qtd_list);
 349                 urb = qtd->urb;
 350
 351                 /* clean up any state from previous QTD ...*/
 352                 if (last) {
 353                         if (likely (last->urb != urb)) {
 354                                 ehci_urb_done(ehci, last->urb, last_status);
 355                                 count++;
 356                                 last_status = -EINPROGRESS;
 357                         }
 358                         ehci_qtd_free (ehci, last);
 359                         last = NULL;
 360                 }
 361
 362                 /* ignore urbs submitted during completions we reported */
 363                 if (qtd == end)
 364                         break;
 365
 366                 /* hardware copies qtd out of qh overlay */
 367                 rmb ();
 368                 token = hc32_to_cpu(ehci, qtd->hw_token);
 369
 370                 /* always clean up qtds the hc de-activated */
 371  retry_xacterr:
 372                 if ((token & QTD_STS_ACTIVE) == 0) {
 373
 374                         /* Report Data Buffer Error: non-fatal but useful */
 375                         if (token & QTD_STS_DBE)
 376                                 ehci_dbg(ehci,
 377                                         "detected DataBufferErr for urb %p ep%d%s len %d, qtd %p [qh %p]\n",
 378                                         urb,
 379                                         usb_endpoint_num(&urb->ep->desc),
 380                                         usb_endpoint_dir_in(&urb->ep->desc) ? "in" : "out",
 381                                         urb->transfer_buffer_length,
 382                                         qtd,
 383                                         qh);
 384
 385                         /* on STALL, error, and short reads this urb must
 386                          * complete and all its qtds must be recycled.
 387                          */
 388                         if ((token & QTD_STS_HALT) != 0) {
 389
 390                                 /* retry transaction errors until we
 391                                  * reach the software xacterr limit
 392                                  */
 393                                 if ((token & QTD_STS_XACT) &&
 394                                                 QTD_CERR(token) == 0 &&
 395                                                 ++qh->xacterrs < QH_XACTERR_MAX &&
 396                                                 !urb->unlinked) {
 397                                         ehci_dbg(ehci,
 398         "detected XactErr len %zu/%zu retry %d\n",
 399         qtd->length - QTD_LENGTH(token), qtd->length, qh->xacterrs);
 400
 401                                         /* reset the token in the qtd and the
 402                                          * qh overlay (which still contains
 403                                          * the qtd) so that we pick up from
 404                                          * where we left off
 405                                          */
 406                                         token &= ~QTD_STS_HALT;
 407                                         token |= QTD_STS_ACTIVE |
 408                                                         (EHCI_TUNE_CERR << 10);
 409                                         qtd->hw_token = cpu_to_hc32(ehci,
 410                                                         token);
 411                                         wmb();
 412                                         hw->hw_token = cpu_to_hc32(ehci,
 413                                                         token);
 414                                         goto retry_xacterr;
 415                                 }
 416                                 stopped = 1;
 417
 418                         /* magic dummy for some short reads; qh won't advance.
 419                          * that silicon quirk can kick in with this dummy too.
 420                          *
 421                          * other short reads won't stop the queue, including
 422                          * control transfers (status stage handles that) or
 423                          * most other single-qtd reads ... the queue stops if
 424                          * URB_SHORT_NOT_OK was set so the driver submitting
 425                          * the urbs could clean it up.
 426                          */
 427                         } else if (IS_SHORT_READ (token)
 428                                         && !(qtd->hw_alt_next
 429                                                 & EHCI_LIST_END(ehci))) {
 430                                 stopped = 1;
 431                         }
 432
 433                 /* stop scanning when we reach qtds the hc is using */
 434                 } else if (likely (!stopped
 435                                 && ehci->rh_state >= EHCI_RH_RUNNING)) {
 436                         break;
 437
 438                 /* scan the whole queue for unlinks whenever it stops */
 439                 } else {
 440                         stopped = 1;
 441
 442                         /* cancel everything if we halt, suspend, etc */
 443                         if (ehci->rh_state < EHCI_RH_RUNNING)
 444                                 last_status = -ESHUTDOWN;
 445
 446                         /* this qtd is active; skip it unless a previous qtd
 447                          * for its urb faulted, or its urb was canceled.
 448                          */
 449                         else if (last_status == -EINPROGRESS && !urb->unlinked)
 450                                 continue;
 451
 452                         /* qh unlinked; token in overlay may be most current */
 453                         if (state == QH_STATE_IDLE
 454                                         && cpu_to_hc32(ehci, qtd->qtd_dma)
 455                                                 == hw->hw_current) {
 456                                 token = hc32_to_cpu(ehci, hw->hw_token);
 457
 458                                 /* An unlink may leave an incomplete
 459                                  * async transaction in the TT buffer.
 460                                  * We have to clear it.
 461                                  */
 462                                 ehci_clear_tt_buffer(ehci, qh, urb, token);
 463                         }
 464                 }
 465
 466                 /* unless we already know the urb's status, collect qtd status
 467                  * and update count of bytes transferred.  in common short read
 468                  * cases with only one data qtd (including control transfers),
 469                  * queue processing won't halt.  but with two or more qtds (for
 470                  * example, with a 32 KB transfer), when the first qtd gets a
 471                  * short read the second must be removed by hand.
 472                  */
 473                 if (last_status == -EINPROGRESS) {
 474                         last_status = qtd_copy_status(ehci, urb,
 475                                         qtd->length, token);
 476                         if (last_status == -EREMOTEIO
 477                                         && (qtd->hw_alt_next
 478                                                 & EHCI_LIST_END(ehci)))
 479                                 last_status = -EINPROGRESS;
 480
 481                         /* As part of low/full-speed endpoint-halt processing
 482                          * we must clear the TT buffer (11.17.5).
 483                          */
 484                         if (unlikely(last_status != -EINPROGRESS &&
 485                                         last_status != -EREMOTEIO)) {
 486                                 /* The TT's in some hubs malfunction when they
 487                                  * receive this request following a STALL (they
 488                                  * stop sending isochronous packets).  Since a
 489                                  * STALL can't leave the TT buffer in a busy
 490                                  * state (if you believe Figures 11-48 - 11-51
 491                                  * in the USB 2.0 spec), we won't clear the TT
 492                                  * buffer in this case.  Strictly speaking this
 493                                  * is a violation of the spec.
 494                                  */
 495                                 if (last_status != -EPIPE)
 496                                         ehci_clear_tt_buffer(ehci, qh, urb,
 497                                                         token);
 498                         }
 499                 }
 500
 501                 /* if we're removing something not at the queue head,
 502                  * patch the hardware queue pointer.
 503                  */
 504                 if (stopped && qtd->qtd_list.prev != &qh->qtd_list) {
 505                         last = list_entry (qtd->qtd_list.prev,
 506                                         struct ehci_qtd, qtd_list);
 507                         last->hw_next = qtd->hw_next;
 508                 }
 509
 510                 /* remove qtd; it's recycled after possible urb completion */
 511                 list_del (&qtd->qtd_list);
 512                 last = qtd;
 513
 514                 /* reinit the xacterr counter for the next qtd */
 515                 qh->xacterrs = 0;
 516         }
 517
 518         /* last urb's completion might still need calling */
 519         if (likely (last != NULL)) {
 520                 ehci_urb_done(ehci, last->urb, last_status);
 521                 count++;
 522                 ehci_qtd_free (ehci, last);
 523         }
 524
 525         /* Do we need to rescan for URBs dequeued during a giveback? */
 526         if (unlikely(qh->needs_rescan)) {
 527                 /* If the QH is already unlinked, do the rescan now. */
 528                 if (state == QH_STATE_IDLE)
 529                         goto rescan;
 530
 531                 /* Otherwise we have to wait until the QH is fully unlinked.
 532                  * Our caller will start an unlink if qh->needs_rescan is
 533                  * set.  But if an unlink has already started, nothing needs
 534                  * to be done.
 535                  */
 536                 if (state != QH_STATE_LINKED)
 537                         qh->needs_rescan = 0;
 538         }
 539
 540         /* restore original state; caller must unlink or relink */
 541         qh->qh_state = state;
 542
 543         /* be sure the hardware's done with the qh before refreshing
 544          * it after fault cleanup, or recovering from silicon wrongly
 545          * overlaying the dummy qtd (which reduces DMA chatter).
 546          */
 547         if (stopped != 0 || hw->hw_qtd_next == EHCI_LIST_END(ehci)) {
 548                 switch (state) {
 549                 case QH_STATE_IDLE:
 550                         qh_refresh(ehci, qh);
 551                         break;
 552                 case QH_STATE_LINKED:
 553                         /* We won't refresh a QH that's linked (after the HC
 554                          * stopped the queue).  That avoids a race:
 555                          *  - HC reads first part of QH;
 556                          *  - CPU updates that first part and the token;
 557                          *  - HC reads rest of that QH, including token
 558                          * Result:  HC gets an inconsistent image, and then
 559                          * DMAs to/from the wrong memory (corrupting it).
 560                          *
 561                          * That should be rare for interrupt transfers,
 562                          * except maybe high bandwidth ...
 563                          */
 564
 565                         /* Tell the caller to start an unlink */
 566                         qh->needs_rescan = 1;
 567                         break;
 568                 /* otherwise, unlink already started */
 569                 }
 570         }
 571
 572         return count;
 573 }
 574
 575 /*-------------------------------------------------------------------------*/
 576
 577 // high bandwidth multiplier, as encoded in highspeed endpoint descriptors
 578 #define hb_mult(wMaxPacketSize) (1 + (((wMaxPacketSize) >> 11) & 0x03))
 579 // ... and packet size, for any kind of endpoint descriptor
 580 #define max_packet(wMaxPacketSize) ((wMaxPacketSize) & 0x07ff)
 581
 582 /*
 583  * reverse of qh_urb_transaction:  free a list of TDs.
 584  * used for cleanup after errors, before HC sees an URB's TDs.
 585  */
 586 static void qtd_list_free (
 587         struct ehci_hcd         *ehci,
 588         struct urb              *urb,
 589         struct list_head        *qtd_list
 590 ) {
 591         struct list_head        *entry, *temp;
 592
 593         list_for_each_safe (entry, temp, qtd_list) {
 594                 struct ehci_qtd *qtd;
 595
 596                 qtd = list_entry (entry, struct ehci_qtd, qtd_list);
 597                 list_del (&qtd->qtd_list);
 598                 ehci_qtd_free (ehci, qtd);
 599         }
 600 }
 601
 602 /*
 603  * create a list of filled qtds for this URB; won't link into qh.
 604  */
 605 static struct list_head *
 606 qh_urb_transaction (
 607         struct ehci_hcd         *ehci,
 608         struct urb              *urb,
 609         struct list_head        *head,
 610         gfp_t                   flags
 611 ) {
 612         struct ehci_qtd         *qtd, *qtd_prev;
 613         dma_addr_t              buf;
 614         int                     len, this_sg_len, maxpacket;
 615         int                     is_input;
 616         u32                     token;
 617         int                     i;
 618         struct scatterlist      *sg;
 619
 620         /*
 621          * URBs map to sequences of QTDs:  one logical transaction
 622          */
 623         qtd = ehci_qtd_alloc (ehci, flags);
 624         if (unlikely (!qtd))
 625                 return NULL;
 626         list_add_tail (&qtd->qtd_list, head);
 627         qtd->urb = urb;
 628
 629         token = QTD_STS_ACTIVE;
 630         token |= (EHCI_TUNE_CERR << 10);
 631         /* for split transactions, SplitXState initialized to zero */
 632
 633         len = urb->transfer_buffer_length;
 634         is_input = usb_pipein (urb->pipe);
 635         if (usb_pipecontrol (urb->pipe)) {
 636                 /* SETUP pid */
 637                 qtd_fill(ehci, qtd, urb->setup_dma,
 638                                 sizeof (struct usb_ctrlrequest),
 639                                 token | (2 /* "setup" */ << 8), 8);
 640
 641                 /* ... and always at least one more pid */
 642                 token ^= QTD_TOGGLE;
 643                 qtd_prev = qtd;
 644                 qtd = ehci_qtd_alloc (ehci, flags);
 645                 if (unlikely (!qtd))
 646                         goto cleanup;
 647                 qtd->urb = urb;
 648                 qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 649                 list_add_tail (&qtd->qtd_list, head);
 650
 651                 /* for zero length DATA stages, STATUS is always IN */
 652                 if (len == 0)
 653                         token |= (1 /* "in" */ << 8);
 654         }
 655
 656         /*
 657          * data transfer stage:  buffer setup
 658          */
 659         i = urb->num_mapped_sgs;
 660         if (len > 0 && i > 0) {
 661                 sg = urb->sg;
 662                 buf = sg_dma_address(sg);
 663
 664                 /* urb->transfer_buffer_length may be smaller than the
 665                  * size of the scatterlist (or vice versa)
 666                  */
 667                 this_sg_len = min_t(int, sg_dma_len(sg), len);
 668         } else {
 669                 sg = NULL;
 670                 buf = urb->transfer_dma;
 671                 this_sg_len = len;
 672         }
 673
 674         if (is_input)
 675                 token |= (1 /* "in" */ << 8);
 676         /* else it's already initted to "out" pid (0 << 8) */
 677
 678         maxpacket = max_packet(usb_maxpacket(urb->dev, urb->pipe, !is_input));
 679
 680         /*
 681          * buffer gets wrapped in one or more qtds;
 682          * last one may be "short" (including zero len)
 683          * and may serve as a control status ack
 684          */
 685         for (;;) {
 686                 int this_qtd_len;
 687
 688                 this_qtd_len = qtd_fill(ehci, qtd, buf, this_sg_len, token,
 689                                 maxpacket);
 690                 this_sg_len -= this_qtd_len;
 691                 len -= this_qtd_len;
 692                 buf += this_qtd_len;
 693
 694                 /*
 695                  * short reads advance to a "magic" dummy instead of the next
 696                  * qtd ... that forces the queue to stop, for manual cleanup.
 697                  * (this will usually be overridden later.)
 698                  */
 699                 if (is_input)
 700                         qtd->hw_alt_next = ehci->async->hw->hw_alt_next;
 701
 702                 /* qh makes control packets use qtd toggle; maybe switch it */
 703                 if ((maxpacket & (this_qtd_len + (maxpacket - 1))) == 0)
 704                         token ^= QTD_TOGGLE;
 705
 706                 if (likely(this_sg_len <= 0)) {
 707                         if (--i <= 0 || len <= 0)
 708                                 break;
 709                         sg = sg_next(sg);
 710                         buf = sg_dma_address(sg);
 711                         this_sg_len = min_t(int, sg_dma_len(sg), len);
 712                 }
 713
 714                 qtd_prev = qtd;
 715                 qtd = ehci_qtd_alloc (ehci, flags);
 716                 if (unlikely (!qtd))
 717                         goto cleanup;
 718                 qtd->urb = urb;
 719                 qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 720                 list_add_tail (&qtd->qtd_list, head);
 721         }
 722
 723         /*
 724          * unless the caller requires manual cleanup after short reads,
 725          * have the alt_next mechanism keep the queue running after the
 726          * last data qtd (the only one, for control and most other cases).
 727          */
 728         if (likely ((urb->transfer_flags & URB_SHORT_NOT_OK) == 0
 729                                 || usb_pipecontrol (urb->pipe)))
 730                 qtd->hw_alt_next = EHCI_LIST_END(ehci);
 731
 732         /*
 733          * control requests may need a terminating data "status" ack;
 734          * other OUT ones may need a terminating short packet
 735          * (zero length).
 736          */
 737         if (likely (urb->transfer_buffer_length != 0)) {
 738                 int     one_more = 0;
 739
 740                 if (usb_pipecontrol (urb->pipe)) {
 741                         one_more = 1;
 742                         token ^= 0x0100;        /* "in" <--> "out"  */
 743                         token |= QTD_TOGGLE;    /* force DATA1 */
 744                 } else if (usb_pipeout(urb->pipe)
 745                                 && (urb->transfer_flags & URB_ZERO_PACKET)
 746                                 && !(urb->transfer_buffer_length % maxpacket)) {
 747                         one_more = 1;
 748                 }
 749                 if (one_more) {
 750                         qtd_prev = qtd;
 751                         qtd = ehci_qtd_alloc (ehci, flags);
 752                         if (unlikely (!qtd))
 753                                 goto cleanup;
 754                         qtd->urb = urb;
 755                         qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 756                         list_add_tail (&qtd->qtd_list, head);
 757
 758                         /* never any data in such packets */
 759                         qtd_fill(ehci, qtd, 0, 0, token, 0);
 760                 }
 761         }
 762
 763         /* by default, enable interrupt on urb completion */
 764         if (likely (!(urb->transfer_flags & URB_NO_INTERRUPT)))
 765                 qtd->hw_token |= cpu_to_hc32(ehci, QTD_IOC);
 766         return head;
 767
 768 cleanup:
 769         qtd_list_free (ehci, urb, head);
 770         return NULL;
 771 }
 772
 773 /*-------------------------------------------------------------------------*/
 774
 775 // Would be best to create all qh's from config descriptors,
 776 // when each interface/altsetting is established.  Unlink
 777 // any previous qh and cancel its urbs first; endpoints are
 778 // implicitly reset then (data toggle too).
 779 // That'd mean updating how usbcore talks to HCDs. (2.7?)
 780
 781
 782 /*
 783  * Each QH holds a qtd list; a QH is used for everything except iso.
 784  *
 785  * For interrupt urbs, the scheduler must set the microframe scheduling
 786  * mask(s) each time the QH gets scheduled.  For highspeed, that's
 787  * just one microframe in the s-mask.  For split interrupt transactions
 788  * there are additional complications: c-mask, maybe FSTNs.
 789  */
 790 static struct ehci_qh *
 791 qh_make (
 792         struct ehci_hcd         *ehci,
 793         struct urb              *urb,
 794         gfp_t                   flags
 795 ) {
 796         struct ehci_qh          *qh = ehci_qh_alloc (ehci, flags);
 797         u32                     info1 = 0, info2 = 0;
 798         int                     is_input, type;
 799         int                     maxp = 0;
 800         struct usb_tt           *tt = urb->dev->tt;
 801         struct ehci_qh_hw       *hw;
 802
 803         if (!qh)
 804                 return qh;
 805
 806         /*
 807          * init endpoint/device data for this QH
 808          */
 809         info1 |= usb_pipeendpoint (urb->pipe) << 8;
 810         info1 |= usb_pipedevice (urb->pipe) << 0;
 811
 812         is_input = usb_pipein (urb->pipe);
 813         type = usb_pipetype (urb->pipe);
 814         maxp = usb_maxpacket (urb->dev, urb->pipe, !is_input);
 815
 816         /* 1024 byte maxpacket is a hardware ceiling.  High bandwidth
 817          * acts like up to 3KB, but is built from smaller packets.
 818          */
 819         if (max_packet(maxp) > 1024) {
 820                 ehci_dbg(ehci, "bogus qh maxpacket %d\n", max_packet(maxp));
 821                 goto done;
 822         }
 823
 824         /* Compute interrupt scheduling parameters just once, and save.
 825          * - allowing for high bandwidth, how many nsec/uframe are used?
 826          * - split transactions need a second CSPLIT uframe; same question
 827          * - splits also need a schedule gap (for full/low speed I/O)
 828          * - qh has a polling interval
 829          *
 830          * For control/bulk requests, the HC or TT handles these.
 831          */
 832         if (type == PIPE_INTERRUPT) {
 833                 qh->usecs = NS_TO_US(usb_calc_bus_time(USB_SPEED_HIGH,
 834                                 is_input, 0,
 835                                 hb_mult(maxp) * max_packet(maxp)));
 836                 qh->start = NO_FRAME;
 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 |= QH_LOW_SPEED;
 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 |= QH_CONTROL_EP;         /* for TT */
 896                         info1 |= QH_TOGGLE_CTL;         /* 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 |= QH_HIGH_SPEED;
 922                 if (type == PIPE_CONTROL) {
 923                         info1 |= (EHCI_TUNE_RL_HS << 28);
 924                         info1 |= 64 << 16;      /* usb2 fixed maxpacket */
 925                         info1 |= QH_TOGGLE_CTL; /* 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                 ehci_dbg(ehci, "bogus dev %p speed %d\n", urb->dev,
 944                         urb->dev->speed);
 945 done:
 946                 qh_destroy(ehci, qh);
 947                 return NULL;
 948         }
 949
 950         /* NOTE:  if (PIPE_INTERRUPT) { scheduler sets s-mask } */
 951
 952         /* init as live, toggle clear, advance to dummy */
 953         qh->qh_state = QH_STATE_IDLE;
 954         hw = qh->hw;
 955         hw->hw_info1 = cpu_to_hc32(ehci, info1);
 956         hw->hw_info2 = cpu_to_hc32(ehci, info2);
 957         qh->is_out = !is_input;
 958         usb_settoggle (urb->dev, usb_pipeendpoint (urb->pipe), !is_input, 1);
 959         qh_refresh (ehci, qh);
 960         return qh;
 961 }
 962
 963 /*-------------------------------------------------------------------------*/
 964
 965 static void enable_async(struct ehci_hcd *ehci)
 966 {
 967         if (ehci->async_count++)
 968                 return;
 969
 970         /* Stop waiting to turn off the async schedule */
 971         ehci->enabled_hrtimer_events &= ~BIT(EHCI_HRTIMER_DISABLE_ASYNC);
 972
 973         /* Don't start the schedule until ASS is 0 */
 974         ehci_poll_ASS(ehci);
 975         turn_on_io_watchdog(ehci);
 976 }
 977
 978 static void disable_async(struct ehci_hcd *ehci)
 979 {
 980         if (--ehci->async_count)
 981                 return;
 982
 983         /* The async schedule and async_unlink list are supposed to be empty */
 984         WARN_ON(ehci->async->qh_next.qh || ehci->async_unlink);
 985
 986         /* Don't turn off the schedule until ASS is 1 */
 987         ehci_poll_ASS(ehci);
 988 }
 989
 990 /* move qh (and its qtds) onto async queue; maybe enable queue.  */
 991
 992 static void qh_link_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 993 {
 994         __hc32          dma = QH_NEXT(ehci, qh->qh_dma);
 995         struct ehci_qh  *head;
 996
 997         /* Don't link a QH if there's a Clear-TT-Buffer pending */
 998         if (unlikely(qh->clearing_tt))
 999                 return;
1000
1001         WARN_ON(qh->qh_state != QH_STATE_IDLE);
1002
1003         /* clear halt and/or toggle; and maybe recover from silicon quirk */
1004         qh_refresh(ehci, qh);
1005
1006         /* splice right after start */
1007         head = ehci->async;
1008         qh->qh_next = head->qh_next;
1009         qh->hw->hw_next = head->hw->hw_next;
1010         wmb ();
1011
1012         head->qh_next.qh = qh;
1013         head->hw->hw_next = dma;
1014
1015         qh->xacterrs = 0;
1016         qh->qh_state = QH_STATE_LINKED;
1017         /* qtd completions reported later by interrupt */
1018
1019         enable_async(ehci);
1020 }
1021
1022 /*-------------------------------------------------------------------------*/
1023
1024 /*
1025  * For control/bulk/interrupt, return QH with these TDs appended.
1026  * Allocates and initializes the QH if necessary.
1027  * Returns null if it can't allocate a QH it needs to.
1028  * If the QH has TDs (urbs) already, that's great.
1029  */
1030 static struct ehci_qh *qh_append_tds (
1031         struct ehci_hcd         *ehci,
1032         struct urb              *urb,
1033         struct list_head        *qtd_list,
1034         int                     epnum,
1035         void                    **ptr
1036 )
1037 {
1038         struct ehci_qh          *qh = NULL;
1039         __hc32                  qh_addr_mask = cpu_to_hc32(ehci, 0x7f);
1040
1041         qh = (struct ehci_qh *) *ptr;
1042         if (unlikely (qh == NULL)) {
1043                 /* can't sleep here, we have ehci->lock... */
1044                 qh = qh_make (ehci, urb, GFP_ATOMIC);
1045                 *ptr = qh;
1046         }
1047         if (likely (qh != NULL)) {
1048                 struct ehci_qtd *qtd;
1049
1050                 if (unlikely (list_empty (qtd_list)))
1051                         qtd = NULL;
1052                 else
1053                         qtd = list_entry (qtd_list->next, struct ehci_qtd,
1054                                         qtd_list);
1055
1056                 /* control qh may need patching ... */
1057                 if (unlikely (epnum == 0)) {
1058
1059                         /* usb_reset_device() briefly reverts to address 0 */
1060                         if (usb_pipedevice (urb->pipe) == 0)
1061                                 qh->hw->hw_info1 &= ~qh_addr_mask;
1062                 }
1063
1064                 /* just one way to queue requests: swap with the dummy qtd.
1065                  * only hc or qh_refresh() ever modify the overlay.
1066                  */
1067                 if (likely (qtd != NULL)) {
1068                         struct ehci_qtd         *dummy;
1069                         dma_addr_t              dma;
1070                         __hc32                  token;
1071
1072                         /* to avoid racing the HC, use the dummy td instead of
1073                          * the first td of our list (becomes new dummy).  both
1074                          * tds stay deactivated until we're done, when the
1075                          * HC is allowed to fetch the old dummy (4.10.2).
1076                          */
1077                         token = qtd->hw_token;
1078                         qtd->hw_token = HALT_BIT(ehci);
1079
1080                         dummy = qh->dummy;
1081
1082                         dma = dummy->qtd_dma;
1083                         *dummy = *qtd;
1084                         dummy->qtd_dma = dma;
1085
1086                         list_del (&qtd->qtd_list);
1087                         list_add (&dummy->qtd_list, qtd_list);
1088                         list_splice_tail(qtd_list, &qh->qtd_list);
1089
1090                         ehci_qtd_init(ehci, qtd, qtd->qtd_dma);
1091                         qh->dummy = qtd;
1092
1093                         /* hc must see the new dummy at list end */
1094                         dma = qtd->qtd_dma;
1095                         qtd = list_entry (qh->qtd_list.prev,
1096                                         struct ehci_qtd, qtd_list);
1097                         qtd->hw_next = QTD_NEXT(ehci, dma);
1098
1099                         /* let the hc process these next qtds */
1100                         wmb ();
1101                         dummy->hw_token = token;
1102
1103                         urb->hcpriv = qh;
1104                 }
1105         }
1106         return qh;
1107 }
1108
1109 /*-------------------------------------------------------------------------*/
1110
1111 static int
1112 submit_async (
1113         struct ehci_hcd         *ehci,
1114         struct urb              *urb,
1115         struct list_head        *qtd_list,
1116         gfp_t                   mem_flags
1117 ) {
1118         int                     epnum;
1119         unsigned long           flags;
1120         struct ehci_qh          *qh = NULL;
1121         int                     rc;
1122
1123         epnum = urb->ep->desc.bEndpointAddress;
1124
1125 #ifdef EHCI_URB_TRACE
1126         {
1127                 struct ehci_qtd *qtd;
1128                 qtd = list_entry(qtd_list->next, struct ehci_qtd, qtd_list);
1129                 ehci_dbg(ehci,
1130                          "%s %s urb %p ep%d%s len %d, qtd %p [qh %p]\n",
1131                          __func__, urb->dev->devpath, urb,
1132                          epnum & 0x0f, (epnum & USB_DIR_IN) ? "in" : "out",
1133                          urb->transfer_buffer_length,
1134                          qtd, urb->ep->hcpriv);
1135         }
1136 #endif
1137
1138         spin_lock_irqsave (&ehci->lock, flags);
1139         if (unlikely(!HCD_HW_ACCESSIBLE(ehci_to_hcd(ehci)))) {
1140                 rc = -ESHUTDOWN;
1141                 goto done;
1142         }
1143         rc = usb_hcd_link_urb_to_ep(ehci_to_hcd(ehci), urb);
1144         if (unlikely(rc))
1145                 goto done;
1146
1147         qh = qh_append_tds(ehci, urb, qtd_list, epnum, &urb->ep->hcpriv);
1148         if (unlikely(qh == NULL)) {
1149                 usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
1150                 rc = -ENOMEM;
1151                 goto done;
1152         }
1153
1154         /* Control/bulk operations through TTs don't need scheduling,
1155          * the HC and TT handle it when the TT has a buffer ready.
1156          */
1157         if (likely (qh->qh_state == QH_STATE_IDLE))
1158                 qh_link_async(ehci, qh);
1159  done:
1160         spin_unlock_irqrestore (&ehci->lock, flags);
1161         if (unlikely (qh == NULL))
1162                 qtd_list_free (ehci, urb, qtd_list);
1163         return rc;
1164 }
1165
1166 /*-------------------------------------------------------------------------*/
1167
1168 static void single_unlink_async(struct ehci_hcd *ehci, struct ehci_qh *qh)
1169 {
1170         struct ehci_qh          *prev;
1171
1172         /* Add to the end of the list of QHs waiting for the next IAAD */
1173         qh->qh_state = QH_STATE_UNLINK;
1174         if (ehci->async_unlink)
1175                 ehci->async_unlink_last->unlink_next = qh;
1176         else
1177                 ehci->async_unlink = qh;
1178         ehci->async_unlink_last = qh;
1179
1180         /* Unlink it from the schedule */
1181         prev = ehci->async;
1182         while (prev->qh_next.qh != qh)
1183                 prev = prev->qh_next.qh;
1184
1185         prev->hw->hw_next = qh->hw->hw_next;
1186         prev->qh_next = qh->qh_next;
1187         if (ehci->qh_scan_next == qh)
1188                 ehci->qh_scan_next = qh->qh_next.qh;
1189 }
1190
1191 static void start_iaa_cycle(struct ehci_hcd *ehci, bool nested)
1192 {
1193         /*
1194          * Do nothing if an IAA cycle is already running or
1195          * if one will be started shortly.
1196          */
1197         if (ehci->async_iaa || ehci->async_unlinking)
1198                 return;
1199
1200         /* Do all the waiting QHs at once */
1201         ehci->async_iaa = ehci->async_unlink;
1202         ehci->async_unlink = NULL;
1203
1204         /* If the controller isn't running, we don't have to wait for it */
1205         if (unlikely(ehci->rh_state < EHCI_RH_RUNNING)) {
1206                 if (!nested)            /* Avoid recursion */
1207                         end_unlink_async(ehci);
1208
1209         /* Otherwise start a new IAA cycle */
1210         } else if (likely(ehci->rh_state == EHCI_RH_RUNNING)) {
1211                 /* Make sure the unlinks are all visible to the hardware */
1212                 wmb();
1213
1214                 ehci_writel(ehci, ehci->command | CMD_IAAD,
1215                                 &ehci->regs->command);
1216                 ehci_readl(ehci, &ehci->regs->command);
1217                 ehci_enable_event(ehci, EHCI_HRTIMER_IAA_WATCHDOG, true);
1218         }
1219 }
1220
1221 /* the async qh for the qtds being unlinked are now gone from the HC */
1222
1223 static void end_unlink_async(struct ehci_hcd *ehci)
1224 {
1225         struct ehci_qh          *qh;
1226
1227         if (ehci->has_synopsys_hc_bug)
1228                 ehci_writel(ehci, (u32) ehci->async->qh_dma,
1229                             &ehci->regs->async_next);
1230
1231         /* Process the idle QHs */
1232  restart:
1233         ehci->async_unlinking = true;
1234         while (ehci->async_iaa) {
1235                 qh = ehci->async_iaa;
1236                 ehci->async_iaa = qh->unlink_next;
1237                 qh->unlink_next = NULL;
1238
1239                 qh->qh_state = QH_STATE_IDLE;
1240                 qh->qh_next.qh = NULL;
1241
1242                 qh_completions(ehci, qh);
1243                 if (!list_empty(&qh->qtd_list) &&
1244                                 ehci->rh_state == EHCI_RH_RUNNING)
1245                         qh_link_async(ehci, qh);
1246                 disable_async(ehci);
1247         }
1248         ehci->async_unlinking = false;
1249
1250         /* Start a new IAA cycle if any QHs are waiting for it */
1251         if (ehci->async_unlink) {
1252                 start_iaa_cycle(ehci, true);
1253                 if (unlikely(ehci->rh_state < EHCI_RH_RUNNING))
1254                         goto restart;
1255         }
1256 }
1257
1258 static void unlink_empty_async(struct ehci_hcd *ehci)
1259 {
1260         struct ehci_qh          *qh, *next;
1261         bool                    stopped = (ehci->rh_state < EHCI_RH_RUNNING);
1262         bool                    check_unlinks_later = false;
1263
1264         /* Unlink all the async QHs that have been empty for a timer cycle */
1265         next = ehci->async->qh_next.qh;
1266         while (next) {
1267                 qh = next;
1268                 next = qh->qh_next.qh;
1269
1270                 if (list_empty(&qh->qtd_list) &&
1271                                 qh->qh_state == QH_STATE_LINKED) {
1272                         if (!stopped && qh->unlink_cycle ==
1273                                         ehci->async_unlink_cycle)
1274                                 check_unlinks_later = true;
1275                         else
1276                                 single_unlink_async(ehci, qh);
1277                 }
1278         }
1279
1280         /* Start a new IAA cycle if any QHs are waiting for it */
1281         if (ehci->async_unlink)
1282                 start_iaa_cycle(ehci, false);
1283
1284         /* QHs that haven't been empty for long enough will be handled later */
1285         if (check_unlinks_later) {
1286                 ehci_enable_event(ehci, EHCI_HRTIMER_ASYNC_UNLINKS, true);
1287                 ++ehci->async_unlink_cycle;
1288         }
1289 }
1290
1291 /* makes sure the async qh will become idle */
1292 /* caller must own ehci->lock */
1293
1294 static void start_unlink_async(struct ehci_hcd *ehci, struct ehci_qh *qh)
1295 {
1296         /*
1297          * If the QH isn't linked then there's nothing we can do
1298          * unless we were called during a giveback, in which case
1299          * qh_completions() has to deal with it.
1300          */
1301         if (qh->qh_state != QH_STATE_LINKED) {
1302                 if (qh->qh_state == QH_STATE_COMPLETING)
1303                         qh->needs_rescan = 1;
1304                 return;
1305         }
1306
1307         single_unlink_async(ehci, qh);
1308         start_iaa_cycle(ehci, false);
1309 }
1310
1311 /*-------------------------------------------------------------------------*/
1312
1313 static void scan_async (struct ehci_hcd *ehci)
1314 {
1315         struct ehci_qh          *qh;
1316         bool                    check_unlinks_later = false;
1317
1318         ehci->qh_scan_next = ehci->async->qh_next.qh;
1319         while (ehci->qh_scan_next) {
1320                 qh = ehci->qh_scan_next;
1321                 ehci->qh_scan_next = qh->qh_next.qh;
1322  rescan:
1323                 /* clean any finished work for this qh */
1324                 if (!list_empty(&qh->qtd_list)) {
1325                         int temp;
1326
1327                         /*
1328                          * Unlinks could happen here; completion reporting
1329                          * drops the lock.  That's why ehci->qh_scan_next
1330                          * always holds the next qh to scan; if the next qh
1331                          * gets unlinked then ehci->qh_scan_next is adjusted
1332                          * in single_unlink_async().
1333                          */
1334                         temp = qh_completions(ehci, qh);
1335                         if (qh->needs_rescan) {
1336                                 start_unlink_async(ehci, qh);
1337                         } else if (list_empty(&qh->qtd_list)
1338                                         && qh->qh_state == QH_STATE_LINKED) {
1339                                 qh->unlink_cycle = ehci->async_unlink_cycle;
1340                                 check_unlinks_later = true;
1341                         } else if (temp != 0)
1342                                 goto rescan;
1343                 }
1344         }
1345
1346         /*
1347          * Unlink empty entries, reducing DMA usage as well
1348          * as HCD schedule-scanning costs.  Delay for any qh
1349          * we just scanned, there's a not-unusual case that it
1350          * doesn't stay idle for long.
1351          */
1352         if (check_unlinks_later && ehci->rh_state == EHCI_RH_RUNNING &&
1353                         !(ehci->enabled_hrtimer_events &
1354                                 BIT(EHCI_HRTIMER_ASYNC_UNLINKS))) {
1355                 ehci_enable_event(ehci, EHCI_HRTIMER_ASYNC_UNLINKS, true);
1356                 ++ehci->async_unlink_cycle;
1357         }
1358 }