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                 /* first qtd may already be partially processed */
 132                 if (cpu_to_hc32(ehci, qtd->qtd_dma) == qh->hw->hw_current)
 133                         qtd = NULL;
 134         }
 135
 136         if (qtd)
 137                 qh_update (ehci, qh, qtd);
 138 }
 139
 140 /*-------------------------------------------------------------------------*/
 141
 142 static void qh_link_async(struct ehci_hcd *ehci, struct ehci_qh *qh);
 143
 144 static void ehci_clear_tt_buffer_complete(struct usb_hcd *hcd,
 145                 struct usb_host_endpoint *ep)
 146 {
 147         struct ehci_hcd         *ehci = hcd_to_ehci(hcd);
 148         struct ehci_qh          *qh = ep->hcpriv;
 149         unsigned long           flags;
 150
 151         spin_lock_irqsave(&ehci->lock, flags);
 152         qh->clearing_tt = 0;
 153         if (qh->qh_state == QH_STATE_IDLE && !list_empty(&qh->qtd_list)
 154                         && ehci->rh_state == EHCI_RH_RUNNING)
 155                 qh_link_async(ehci, qh);
 156         spin_unlock_irqrestore(&ehci->lock, flags);
 157 }
 158
 159 static void ehci_clear_tt_buffer(struct ehci_hcd *ehci, struct ehci_qh *qh,
 160                 struct urb *urb, u32 token)
 161 {
 162
 163         /* If an async split transaction gets an error or is unlinked,
 164          * the TT buffer may be left in an indeterminate state.  We
 165          * have to clear the TT buffer.
 166          *
 167          * Note: this routine is never called for Isochronous transfers.
 168          */
 169         if (urb->dev->tt && !usb_pipeint(urb->pipe) && !qh->clearing_tt) {
 170 #ifdef DEBUG
 171                 struct usb_device *tt = urb->dev->tt->hub;
 172                 dev_dbg(&tt->dev,
 173                         "clear tt buffer port %d, a%d ep%d t%08x\n",
 174                         urb->dev->ttport, urb->dev->devnum,
 175                         usb_pipeendpoint(urb->pipe), token);
 176 #endif /* DEBUG */
 177                 if (!ehci_is_TDI(ehci)
 178                                 || urb->dev->tt->hub !=
 179                                    ehci_to_hcd(ehci)->self.root_hub) {
 180                         if (usb_hub_clear_tt_buffer(urb) == 0)
 181                                 qh->clearing_tt = 1;
 182                 } else {
 183
 184                         /* REVISIT ARC-derived cores don't clear the root
 185                          * hub TT buffer in this way...
 186                          */
 187                 }
 188         }
 189 }
 190
 191 static int qtd_copy_status (
 192         struct ehci_hcd *ehci,
 193         struct urb *urb,
 194         size_t length,
 195         u32 token
 196 )
 197 {
 198         int     status = -EINPROGRESS;
 199
 200         /* count IN/OUT bytes, not SETUP (even short packets) */
 201         if (likely (QTD_PID (token) != 2))
 202                 urb->actual_length += length - QTD_LENGTH (token);
 203
 204         /* don't modify error codes */
 205         if (unlikely(urb->unlinked))
 206                 return status;
 207
 208         /* force cleanup after short read; not always an error */
 209         if (unlikely (IS_SHORT_READ (token)))
 210                 status = -EREMOTEIO;
 211
 212         /* serious "can't proceed" faults reported by the hardware */
 213         if (token & QTD_STS_HALT) {
 214                 if (token & QTD_STS_BABBLE) {
 215                         /* FIXME "must" disable babbling device's port too */
 216                         status = -EOVERFLOW;
 217                 /* CERR nonzero + halt --> stall */
 218                 } else if (QTD_CERR(token)) {
 219                         status = -EPIPE;
 220
 221                 /* In theory, more than one of the following bits can be set
 222                  * since they are sticky and the transaction is retried.
 223                  * Which to test first is rather arbitrary.
 224                  */
 225                 } else if (token & QTD_STS_MMF) {
 226                         /* fs/ls interrupt xfer missed the complete-split */
 227                         status = -EPROTO;
 228                 } else if (token & QTD_STS_DBE) {
 229                         status = (QTD_PID (token) == 1) /* IN ? */
 230                                 ? -ENOSR  /* hc couldn't read data */
 231                                 : -ECOMM; /* hc couldn't write data */
 232                 } else if (token & QTD_STS_XACT) {
 233                         /* timeout, bad CRC, wrong PID, etc */
 234                         ehci_dbg(ehci, "devpath %s ep%d%s 3strikes\n",
 235                                 urb->dev->devpath,
 236                                 usb_pipeendpoint(urb->pipe),
 237                                 usb_pipein(urb->pipe) ? "in" : "out");
 238                         status = -EPROTO;
 239                 } else {        /* unknown */
 240                         status = -EPROTO;
 241                 }
 242
 243                 ehci_vdbg (ehci,
 244                         "dev%d ep%d%s qtd token %08x --> status %d\n",
 245                         usb_pipedevice (urb->pipe),
 246                         usb_pipeendpoint (urb->pipe),
 247                         usb_pipein (urb->pipe) ? "in" : "out",
 248                         token, status);
 249         }
 250
 251         return status;
 252 }
 253
 254 static void
 255 ehci_urb_done(struct ehci_hcd *ehci, struct urb *urb, int status)
 256 __releases(ehci->lock)
 257 __acquires(ehci->lock)
 258 {
 259         if (likely (urb->hcpriv != NULL)) {
 260                 struct ehci_qh  *qh = (struct ehci_qh *) urb->hcpriv;
 261
 262                 /* S-mask in a QH means it's an interrupt urb */
 263                 if ((qh->hw->hw_info2 & cpu_to_hc32(ehci, QH_SMASK)) != 0) {
 264
 265                         /* ... update hc-wide periodic stats (for usbfs) */
 266                         ehci_to_hcd(ehci)->self.bandwidth_int_reqs--;
 267                 }
 268         }
 269
 270         if (unlikely(urb->unlinked)) {
 271                 COUNT(ehci->stats.unlink);
 272         } else {
 273                 /* report non-error and short read status as zero */
 274                 if (status == -EINPROGRESS || status == -EREMOTEIO)
 275                         status = 0;
 276                 COUNT(ehci->stats.complete);
 277         }
 278
 279 #ifdef EHCI_URB_TRACE
 280         ehci_dbg (ehci,
 281                 "%s %s urb %p ep%d%s status %d len %d/%d\n",
 282                 __func__, urb->dev->devpath, urb,
 283                 usb_pipeendpoint (urb->pipe),
 284                 usb_pipein (urb->pipe) ? "in" : "out",
 285                 status,
 286                 urb->actual_length, urb->transfer_buffer_length);
 287 #endif
 288
 289         /* complete() can reenter this HCD */
 290         usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
 291         spin_unlock (&ehci->lock);
 292         usb_hcd_giveback_urb(ehci_to_hcd(ehci), urb, status);
 293         spin_lock (&ehci->lock);
 294 }
 295
 296 static int qh_schedule (struct ehci_hcd *ehci, struct ehci_qh *qh);
 297
 298 /*
 299  * Process and free completed qtds for a qh, returning URBs to drivers.
 300  * Chases up to qh->hw_current.  Returns number of completions called,
 301  * indicating how much "real" work we did.
 302  */
 303 static unsigned
 304 qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
 305 {
 306         struct ehci_qtd         *last, *end = qh->dummy;
 307         struct list_head        *entry, *tmp;
 308         int                     last_status;
 309         int                     stopped;
 310         unsigned                count = 0;
 311         u8                      state;
 312         struct ehci_qh_hw       *hw = qh->hw;
 313
 314         if (unlikely (list_empty (&qh->qtd_list)))
 315                 return count;
 316
 317         /* completions (or tasks on other cpus) must never clobber HALT
 318          * till we've gone through and cleaned everything up, even when
 319          * they add urbs to this qh's queue or mark them for unlinking.
 320          *
 321          * NOTE:  unlinking expects to be done in queue order.
 322          *
 323          * It's a bug for qh->qh_state to be anything other than
 324          * QH_STATE_IDLE, unless our caller is scan_async() or
 325          * scan_intr().
 326          */
 327         state = qh->qh_state;
 328         qh->qh_state = QH_STATE_COMPLETING;
 329         stopped = (state == QH_STATE_IDLE);
 330
 331  rescan:
 332         last = NULL;
 333         last_status = -EINPROGRESS;
 334         qh->needs_rescan = 0;
 335
 336         /* remove de-activated QTDs from front of queue.
 337          * after faults (including short reads), cleanup this urb
 338          * then let the queue advance.
 339          * if queue is stopped, handles unlinks.
 340          */
 341         list_for_each_safe (entry, tmp, &qh->qtd_list) {
 342                 struct ehci_qtd *qtd;
 343                 struct urb      *urb;
 344                 u32             token = 0;
 345
 346                 qtd = list_entry (entry, struct ehci_qtd, qtd_list);
 347                 urb = qtd->urb;
 348
 349                 /* clean up any state from previous QTD ...*/
 350                 if (last) {
 351                         if (likely (last->urb != urb)) {
 352                                 ehci_urb_done(ehci, last->urb, last_status);
 353                                 count++;
 354                                 last_status = -EINPROGRESS;
 355                         }
 356                         ehci_qtd_free (ehci, last);
 357                         last = NULL;
 358                 }
 359
 360                 /* ignore urbs submitted during completions we reported */
 361                 if (qtd == end)
 362                         break;
 363
 364                 /* hardware copies qtd out of qh overlay */
 365                 rmb ();
 366                 token = hc32_to_cpu(ehci, qtd->hw_token);
 367
 368                 /* always clean up qtds the hc de-activated */
 369  retry_xacterr:
 370                 if ((token & QTD_STS_ACTIVE) == 0) {
 371
 372                         /* Report Data Buffer Error: non-fatal but useful */
 373                         if (token & QTD_STS_DBE)
 374                                 ehci_dbg(ehci,
 375                                         "detected DataBufferErr for urb %p ep%d%s len %d, qtd %p [qh %p]\n",
 376                                         urb,
 377                                         usb_endpoint_num(&urb->ep->desc),
 378                                         usb_endpoint_dir_in(&urb->ep->desc) ? "in" : "out",
 379                                         urb->transfer_buffer_length,
 380                                         qtd,
 381                                         qh);
 382
 383                         /* on STALL, error, and short reads this urb must
 384                          * complete and all its qtds must be recycled.
 385                          */
 386                         if ((token & QTD_STS_HALT) != 0) {
 387
 388                                 /* retry transaction errors until we
 389                                  * reach the software xacterr limit
 390                                  */
 391                                 if ((token & QTD_STS_XACT) &&
 392                                                 QTD_CERR(token) == 0 &&
 393                                                 ++qh->xacterrs < QH_XACTERR_MAX &&
 394                                                 !urb->unlinked) {
 395                                         ehci_dbg(ehci,
 396         "detected XactErr len %zu/%zu retry %d\n",
 397         qtd->length - QTD_LENGTH(token), qtd->length, qh->xacterrs);
 398
 399                                         /* reset the token in the qtd and the
 400                                          * qh overlay (which still contains
 401                                          * the qtd) so that we pick up from
 402                                          * where we left off
 403                                          */
 404                                         token &= ~QTD_STS_HALT;
 405                                         token |= QTD_STS_ACTIVE |
 406                                                         (EHCI_TUNE_CERR << 10);
 407                                         qtd->hw_token = cpu_to_hc32(ehci,
 408                                                         token);
 409                                         wmb();
 410                                         hw->hw_token = cpu_to_hc32(ehci,
 411                                                         token);
 412                                         goto retry_xacterr;
 413                                 }
 414                                 stopped = 1;
 415
 416                         /* magic dummy for some short reads; qh won't advance.
 417                          * that silicon quirk can kick in with this dummy too.
 418                          *
 419                          * other short reads won't stop the queue, including
 420                          * control transfers (status stage handles that) or
 421                          * most other single-qtd reads ... the queue stops if
 422                          * URB_SHORT_NOT_OK was set so the driver submitting
 423                          * the urbs could clean it up.
 424                          */
 425                         } else if (IS_SHORT_READ (token)
 426                                         && !(qtd->hw_alt_next
 427                                                 & EHCI_LIST_END(ehci))) {
 428                                 stopped = 1;
 429                         }
 430
 431                 /* stop scanning when we reach qtds the hc is using */
 432                 } else if (likely (!stopped
 433                                 && ehci->rh_state >= EHCI_RH_RUNNING)) {
 434                         break;
 435
 436                 /* scan the whole queue for unlinks whenever it stops */
 437                 } else {
 438                         stopped = 1;
 439
 440                         /* cancel everything if we halt, suspend, etc */
 441                         if (ehci->rh_state < EHCI_RH_RUNNING)
 442                                 last_status = -ESHUTDOWN;
 443
 444                         /* this qtd is active; skip it unless a previous qtd
 445                          * for its urb faulted, or its urb was canceled.
 446                          */
 447                         else if (last_status == -EINPROGRESS && !urb->unlinked)
 448                                 continue;
 449
 450                         /* qh unlinked; token in overlay may be most current */
 451                         if (state == QH_STATE_IDLE
 452                                         && cpu_to_hc32(ehci, qtd->qtd_dma)
 453                                                 == hw->hw_current) {
 454                                 token = hc32_to_cpu(ehci, hw->hw_token);
 455
 456                                 /* An unlink may leave an incomplete
 457                                  * async transaction in the TT buffer.
 458                                  * We have to clear it.
 459                                  */
 460                                 ehci_clear_tt_buffer(ehci, qh, urb, token);
 461                         }
 462                 }
 463
 464                 /* unless we already know the urb's status, collect qtd status
 465                  * and update count of bytes transferred.  in common short read
 466                  * cases with only one data qtd (including control transfers),
 467                  * queue processing won't halt.  but with two or more qtds (for
 468                  * example, with a 32 KB transfer), when the first qtd gets a
 469                  * short read the second must be removed by hand.
 470                  */
 471                 if (last_status == -EINPROGRESS) {
 472                         last_status = qtd_copy_status(ehci, urb,
 473                                         qtd->length, token);
 474                         if (last_status == -EREMOTEIO
 475                                         && (qtd->hw_alt_next
 476                                                 & EHCI_LIST_END(ehci)))
 477                                 last_status = -EINPROGRESS;
 478
 479                         /* As part of low/full-speed endpoint-halt processing
 480                          * we must clear the TT buffer (11.17.5).
 481                          */
 482                         if (unlikely(last_status != -EINPROGRESS &&
 483                                         last_status != -EREMOTEIO)) {
 484                                 /* The TT's in some hubs malfunction when they
 485                                  * receive this request following a STALL (they
 486                                  * stop sending isochronous packets).  Since a
 487                                  * STALL can't leave the TT buffer in a busy
 488                                  * state (if you believe Figures 11-48 - 11-51
 489                                  * in the USB 2.0 spec), we won't clear the TT
 490                                  * buffer in this case.  Strictly speaking this
 491                                  * is a violation of the spec.
 492                                  */
 493                                 if (last_status != -EPIPE)
 494                                         ehci_clear_tt_buffer(ehci, qh, urb,
 495                                                         token);
 496                         }
 497                 }
 498
 499                 /* if we're removing something not at the queue head,
 500                  * patch the hardware queue pointer.
 501                  */
 502                 if (stopped && qtd->qtd_list.prev != &qh->qtd_list) {
 503                         last = list_entry (qtd->qtd_list.prev,
 504                                         struct ehci_qtd, qtd_list);
 505                         last->hw_next = qtd->hw_next;
 506                 }
 507
 508                 /* remove qtd; it's recycled after possible urb completion */
 509                 list_del (&qtd->qtd_list);
 510                 last = qtd;
 511
 512                 /* reinit the xacterr counter for the next qtd */
 513                 qh->xacterrs = 0;
 514         }
 515
 516         /* last urb's completion might still need calling */
 517         if (likely (last != NULL)) {
 518                 ehci_urb_done(ehci, last->urb, last_status);
 519                 count++;
 520                 ehci_qtd_free (ehci, last);
 521         }
 522
 523         /* Do we need to rescan for URBs dequeued during a giveback? */
 524         if (unlikely(qh->needs_rescan)) {
 525                 /* If the QH is already unlinked, do the rescan now. */
 526                 if (state == QH_STATE_IDLE)
 527                         goto rescan;
 528
 529                 /* Otherwise we have to wait until the QH is fully unlinked.
 530                  * Our caller will start an unlink if qh->needs_rescan is
 531                  * set.  But if an unlink has already started, nothing needs
 532                  * to be done.
 533                  */
 534                 if (state != QH_STATE_LINKED)
 535                         qh->needs_rescan = 0;
 536         }
 537
 538         /* restore original state; caller must unlink or relink */
 539         qh->qh_state = state;
 540
 541         /* be sure the hardware's done with the qh before refreshing
 542          * it after fault cleanup, or recovering from silicon wrongly
 543          * overlaying the dummy qtd (which reduces DMA chatter).
 544          */
 545         if (stopped != 0 || hw->hw_qtd_next == EHCI_LIST_END(ehci)) {
 546                 switch (state) {
 547                 case QH_STATE_IDLE:
 548                         qh_refresh(ehci, qh);
 549                         break;
 550                 case QH_STATE_LINKED:
 551                         /* We won't refresh a QH that's linked (after the HC
 552                          * stopped the queue).  That avoids a race:
 553                          *  - HC reads first part of QH;
 554                          *  - CPU updates that first part and the token;
 555                          *  - HC reads rest of that QH, including token
 556                          * Result:  HC gets an inconsistent image, and then
 557                          * DMAs to/from the wrong memory (corrupting it).
 558                          *
 559                          * That should be rare for interrupt transfers,
 560                          * except maybe high bandwidth ...
 561                          */
 562
 563                         /* Tell the caller to start an unlink */
 564                         qh->needs_rescan = 1;
 565                         break;
 566                 /* otherwise, unlink already started */
 567                 }
 568         }
 569
 570         return count;
 571 }
 572
 573 /*-------------------------------------------------------------------------*/
 574
 575 // high bandwidth multiplier, as encoded in highspeed endpoint descriptors
 576 #define hb_mult(wMaxPacketSize) (1 + (((wMaxPacketSize) >> 11) & 0x03))
 577 // ... and packet size, for any kind of endpoint descriptor
 578 #define max_packet(wMaxPacketSize) ((wMaxPacketSize) & 0x07ff)
 579
 580 /*
 581  * reverse of qh_urb_transaction:  free a list of TDs.
 582  * used for cleanup after errors, before HC sees an URB's TDs.
 583  */
 584 static void qtd_list_free (
 585         struct ehci_hcd         *ehci,
 586         struct urb              *urb,
 587         struct list_head        *qtd_list
 588 ) {
 589         struct list_head        *entry, *temp;
 590
 591         list_for_each_safe (entry, temp, qtd_list) {
 592                 struct ehci_qtd *qtd;
 593
 594                 qtd = list_entry (entry, struct ehci_qtd, qtd_list);
 595                 list_del (&qtd->qtd_list);
 596                 ehci_qtd_free (ehci, qtd);
 597         }
 598 }
 599
 600 /*
 601  * create a list of filled qtds for this URB; won't link into qh.
 602  */
 603 static struct list_head *
 604 qh_urb_transaction (
 605         struct ehci_hcd         *ehci,
 606         struct urb              *urb,
 607         struct list_head        *head,
 608         gfp_t                   flags
 609 ) {
 610         struct ehci_qtd         *qtd, *qtd_prev;
 611         dma_addr_t              buf;
 612         int                     len, this_sg_len, maxpacket;
 613         int                     is_input;
 614         u32                     token;
 615         int                     i;
 616         struct scatterlist      *sg;
 617
 618         /*
 619          * URBs map to sequences of QTDs:  one logical transaction
 620          */
 621         qtd = ehci_qtd_alloc (ehci, flags);
 622         if (unlikely (!qtd))
 623                 return NULL;
 624         list_add_tail (&qtd->qtd_list, head);
 625         qtd->urb = urb;
 626
 627         token = QTD_STS_ACTIVE;
 628         token |= (EHCI_TUNE_CERR << 10);
 629         /* for split transactions, SplitXState initialized to zero */
 630
 631         len = urb->transfer_buffer_length;
 632         is_input = usb_pipein (urb->pipe);
 633         if (usb_pipecontrol (urb->pipe)) {
 634                 /* SETUP pid */
 635                 qtd_fill(ehci, qtd, urb->setup_dma,
 636                                 sizeof (struct usb_ctrlrequest),
 637                                 token | (2 /* "setup" */ << 8), 8);
 638
 639                 /* ... and always at least one more pid */
 640                 token ^= QTD_TOGGLE;
 641                 qtd_prev = qtd;
 642                 qtd = ehci_qtd_alloc (ehci, flags);
 643                 if (unlikely (!qtd))
 644                         goto cleanup;
 645                 qtd->urb = urb;
 646                 qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 647                 list_add_tail (&qtd->qtd_list, head);
 648
 649                 /* for zero length DATA stages, STATUS is always IN */
 650                 if (len == 0)
 651                         token |= (1 /* "in" */ << 8);
 652         }
 653
 654         /*
 655          * data transfer stage:  buffer setup
 656          */
 657         i = urb->num_mapped_sgs;
 658         if (len > 0 && i > 0) {
 659                 sg = urb->sg;
 660                 buf = sg_dma_address(sg);
 661
 662                 /* urb->transfer_buffer_length may be smaller than the
 663                  * size of the scatterlist (or vice versa)
 664                  */
 665                 this_sg_len = min_t(int, sg_dma_len(sg), len);
 666         } else {
 667                 sg = NULL;
 668                 buf = urb->transfer_dma;
 669                 this_sg_len = len;
 670         }
 671
 672         if (is_input)
 673                 token |= (1 /* "in" */ << 8);
 674         /* else it's already initted to "out" pid (0 << 8) */
 675
 676         maxpacket = max_packet(usb_maxpacket(urb->dev, urb->pipe, !is_input));
 677
 678         /*
 679          * buffer gets wrapped in one or more qtds;
 680          * last one may be "short" (including zero len)
 681          * and may serve as a control status ack
 682          */
 683         for (;;) {
 684                 int this_qtd_len;
 685
 686                 this_qtd_len = qtd_fill(ehci, qtd, buf, this_sg_len, token,
 687                                 maxpacket);
 688                 this_sg_len -= this_qtd_len;
 689                 len -= this_qtd_len;
 690                 buf += this_qtd_len;
 691
 692                 /*
 693                  * short reads advance to a "magic" dummy instead of the next
 694                  * qtd ... that forces the queue to stop, for manual cleanup.
 695                  * (this will usually be overridden later.)
 696                  */
 697                 if (is_input)
 698                         qtd->hw_alt_next = ehci->async->hw->hw_alt_next;
 699
 700                 /* qh makes control packets use qtd toggle; maybe switch it */
 701                 if ((maxpacket & (this_qtd_len + (maxpacket - 1))) == 0)
 702                         token ^= QTD_TOGGLE;
 703
 704                 if (likely(this_sg_len <= 0)) {
 705                         if (--i <= 0 || len <= 0)
 706                                 break;
 707                         sg = sg_next(sg);
 708                         buf = sg_dma_address(sg);
 709                         this_sg_len = min_t(int, sg_dma_len(sg), len);
 710                 }
 711
 712                 qtd_prev = qtd;
 713                 qtd = ehci_qtd_alloc (ehci, flags);
 714                 if (unlikely (!qtd))
 715                         goto cleanup;
 716                 qtd->urb = urb;
 717                 qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 718                 list_add_tail (&qtd->qtd_list, head);
 719         }
 720
 721         /*
 722          * unless the caller requires manual cleanup after short reads,
 723          * have the alt_next mechanism keep the queue running after the
 724          * last data qtd (the only one, for control and most other cases).
 725          */
 726         if (likely ((urb->transfer_flags & URB_SHORT_NOT_OK) == 0
 727                                 || usb_pipecontrol (urb->pipe)))
 728                 qtd->hw_alt_next = EHCI_LIST_END(ehci);
 729
 730         /*
 731          * control requests may need a terminating data "status" ack;
 732          * other OUT ones may need a terminating short packet
 733          * (zero length).
 734          */
 735         if (likely (urb->transfer_buffer_length != 0)) {
 736                 int     one_more = 0;
 737
 738                 if (usb_pipecontrol (urb->pipe)) {
 739                         one_more = 1;
 740                         token ^= 0x0100;        /* "in" <--> "out"  */
 741                         token |= QTD_TOGGLE;    /* force DATA1 */
 742                 } else if (usb_pipeout(urb->pipe)
 743                                 && (urb->transfer_flags & URB_ZERO_PACKET)
 744                                 && !(urb->transfer_buffer_length % maxpacket)) {
 745                         one_more = 1;
 746                 }
 747                 if (one_more) {
 748                         qtd_prev = qtd;
 749                         qtd = ehci_qtd_alloc (ehci, flags);
 750                         if (unlikely (!qtd))
 751                                 goto cleanup;
 752                         qtd->urb = urb;
 753                         qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 754                         list_add_tail (&qtd->qtd_list, head);
 755
 756                         /* never any data in such packets */
 757                         qtd_fill(ehci, qtd, 0, 0, token, 0);
 758                 }
 759         }
 760
 761         /* by default, enable interrupt on urb completion */
 762         if (likely (!(urb->transfer_flags & URB_NO_INTERRUPT)))
 763                 qtd->hw_token |= cpu_to_hc32(ehci, QTD_IOC);
 764         return head;
 765
 766 cleanup:
 767         qtd_list_free (ehci, urb, head);
 768         return NULL;
 769 }
 770
 771 /*-------------------------------------------------------------------------*/
 772
 773 // Would be best to create all qh's from config descriptors,
 774 // when each interface/altsetting is established.  Unlink
 775 // any previous qh and cancel its urbs first; endpoints are
 776 // implicitly reset then (data toggle too).
 777 // That'd mean updating how usbcore talks to HCDs. (2.7?)
 778
 779
 780 /*
 781  * Each QH holds a qtd list; a QH is used for everything except iso.
 782  *
 783  * For interrupt urbs, the scheduler must set the microframe scheduling
 784  * mask(s) each time the QH gets scheduled.  For highspeed, that's
 785  * just one microframe in the s-mask.  For split interrupt transactions
 786  * there are additional complications: c-mask, maybe FSTNs.
 787  */
 788 static struct ehci_qh *
 789 qh_make (
 790         struct ehci_hcd         *ehci,
 791         struct urb              *urb,
 792         gfp_t                   flags
 793 ) {
 794         struct ehci_qh          *qh = ehci_qh_alloc (ehci, flags);
 795         u32                     info1 = 0, info2 = 0;
 796         int                     is_input, type;
 797         int                     maxp = 0;
 798         struct usb_tt           *tt = urb->dev->tt;
 799         struct ehci_qh_hw       *hw;
 800
 801         if (!qh)
 802                 return qh;
 803
 804         /*
 805          * init endpoint/device data for this QH
 806          */
 807         info1 |= usb_pipeendpoint (urb->pipe) << 8;
 808         info1 |= usb_pipedevice (urb->pipe) << 0;
 809
 810         is_input = usb_pipein (urb->pipe);
 811         type = usb_pipetype (urb->pipe);
 812         maxp = usb_maxpacket (urb->dev, urb->pipe, !is_input);
 813
 814         /* 1024 byte maxpacket is a hardware ceiling.  High bandwidth
 815          * acts like up to 3KB, but is built from smaller packets.
 816          */
 817         if (max_packet(maxp) > 1024) {
 818                 ehci_dbg(ehci, "bogus qh maxpacket %d\n", max_packet(maxp));
 819                 goto done;
 820         }
 821
 822         /* Compute interrupt scheduling parameters just once, and save.
 823          * - allowing for high bandwidth, how many nsec/uframe are used?
 824          * - split transactions need a second CSPLIT uframe; same question
 825          * - splits also need a schedule gap (for full/low speed I/O)
 826          * - qh has a polling interval
 827          *
 828          * For control/bulk requests, the HC or TT handles these.
 829          */
 830         if (type == PIPE_INTERRUPT) {
 831                 qh->usecs = NS_TO_US(usb_calc_bus_time(USB_SPEED_HIGH,
 832                                 is_input, 0,
 833                                 hb_mult(maxp) * max_packet(maxp)));
 834                 qh->start = NO_FRAME;
 835
 836                 if (urb->dev->speed == USB_SPEED_HIGH) {
 837                         qh->c_usecs = 0;
 838                         qh->gap_uf = 0;
 839
 840                         qh->period = urb->interval >> 3;
 841                         if (qh->period == 0 && urb->interval != 1) {
 842                                 /* NOTE interval 2 or 4 uframes could work.
 843                                  * But interval 1 scheduling is simpler, and
 844                                  * includes high bandwidth.
 845                                  */
 846                                 urb->interval = 1;
 847                         } else if (qh->period > ehci->periodic_size) {
 848                                 qh->period = ehci->periodic_size;
 849                                 urb->interval = qh->period << 3;
 850                         }
 851                 } else {
 852                         int             think_time;
 853
 854                         /* gap is f(FS/LS transfer times) */
 855                         qh->gap_uf = 1 + usb_calc_bus_time (urb->dev->speed,
 856                                         is_input, 0, maxp) / (125 * 1000);
 857
 858                         /* FIXME this just approximates SPLIT/CSPLIT times */
 859                         if (is_input) {         // SPLIT, gap, CSPLIT+DATA
 860                                 qh->c_usecs = qh->usecs + HS_USECS (0);
 861                                 qh->usecs = HS_USECS (1);
 862                         } else {                // SPLIT+DATA, gap, CSPLIT
 863                                 qh->usecs += HS_USECS (1);
 864                                 qh->c_usecs = HS_USECS (0);
 865                         }
 866
 867                         think_time = tt ? tt->think_time : 0;
 868                         qh->tt_usecs = NS_TO_US (think_time +
 869                                         usb_calc_bus_time (urb->dev->speed,
 870                                         is_input, 0, max_packet (maxp)));
 871                         qh->period = urb->interval;
 872                         if (qh->period > ehci->periodic_size) {
 873                                 qh->period = ehci->periodic_size;
 874                                 urb->interval = qh->period;
 875                         }
 876                 }
 877         }
 878
 879         /* support for tt scheduling, and access to toggles */
 880         qh->dev = urb->dev;
 881
 882         /* using TT? */
 883         switch (urb->dev->speed) {
 884         case USB_SPEED_LOW:
 885                 info1 |= QH_LOW_SPEED;
 886                 /* FALL THROUGH */
 887
 888         case USB_SPEED_FULL:
 889                 /* EPS 0 means "full" */
 890                 if (type != PIPE_INTERRUPT)
 891                         info1 |= (EHCI_TUNE_RL_TT << 28);
 892                 if (type == PIPE_CONTROL) {
 893                         info1 |= QH_CONTROL_EP;         /* for TT */
 894                         info1 |= QH_TOGGLE_CTL;         /* toggle from qtd */
 895                 }
 896                 info1 |= maxp << 16;
 897
 898                 info2 |= (EHCI_TUNE_MULT_TT << 30);
 899
 900                 /* Some Freescale processors have an erratum in which the
 901                  * port number in the queue head was 0..N-1 instead of 1..N.
 902                  */
 903                 if (ehci_has_fsl_portno_bug(ehci))
 904                         info2 |= (urb->dev->ttport-1) << 23;
 905                 else
 906                         info2 |= urb->dev->ttport << 23;
 907
 908                 /* set the address of the TT; for TDI's integrated
 909                  * root hub tt, leave it zeroed.
 910                  */
 911                 if (tt && tt->hub != ehci_to_hcd(ehci)->self.root_hub)
 912                         info2 |= tt->hub->devnum << 16;
 913
 914                 /* NOTE:  if (PIPE_INTERRUPT) { scheduler sets c-mask } */
 915
 916                 break;
 917
 918         case USB_SPEED_HIGH:            /* no TT involved */
 919                 info1 |= QH_HIGH_SPEED;
 920                 if (type == PIPE_CONTROL) {
 921                         info1 |= (EHCI_TUNE_RL_HS << 28);
 922                         info1 |= 64 << 16;      /* usb2 fixed maxpacket */
 923                         info1 |= QH_TOGGLE_CTL; /* toggle from qtd */
 924                         info2 |= (EHCI_TUNE_MULT_HS << 30);
 925                 } else if (type == PIPE_BULK) {
 926                         info1 |= (EHCI_TUNE_RL_HS << 28);
 927                         /* The USB spec says that high speed bulk endpoints
 928                          * always use 512 byte maxpacket.  But some device
 929                          * vendors decided to ignore that, and MSFT is happy
 930                          * to help them do so.  So now people expect to use
 931                          * such nonconformant devices with Linux too; sigh.
 932                          */
 933                         info1 |= max_packet(maxp) << 16;
 934                         info2 |= (EHCI_TUNE_MULT_HS << 30);
 935                 } else {                /* PIPE_INTERRUPT */
 936                         info1 |= max_packet (maxp) << 16;
 937                         info2 |= hb_mult (maxp) << 30;
 938                 }
 939                 break;
 940         default:
 941                 ehci_dbg(ehci, "bogus dev %p speed %d\n", urb->dev,
 942                         urb->dev->speed);
 943 done:
 944                 qh_destroy(ehci, qh);
 945                 return NULL;
 946         }
 947
 948         /* NOTE:  if (PIPE_INTERRUPT) { scheduler sets s-mask } */
 949
 950         /* init as live, toggle clear, advance to dummy */
 951         qh->qh_state = QH_STATE_IDLE;
 952         hw = qh->hw;
 953         hw->hw_info1 = cpu_to_hc32(ehci, info1);
 954         hw->hw_info2 = cpu_to_hc32(ehci, info2);
 955         qh->is_out = !is_input;
 956         usb_settoggle (urb->dev, usb_pipeendpoint (urb->pipe), !is_input, 1);
 957         qh_refresh (ehci, qh);
 958         return qh;
 959 }
 960
 961 /*-------------------------------------------------------------------------*/
 962
 963 static void enable_async(struct ehci_hcd *ehci)
 964 {
 965         if (ehci->async_count++)
 966                 return;
 967
 968         /* Stop waiting to turn off the async schedule */
 969         ehci->enabled_hrtimer_events &= ~BIT(EHCI_HRTIMER_DISABLE_ASYNC);
 970
 971         /* Don't start the schedule until ASS is 0 */
 972         ehci_poll_ASS(ehci);
 973         turn_on_io_watchdog(ehci);
 974 }
 975
 976 static void disable_async(struct ehci_hcd *ehci)
 977 {
 978         if (--ehci->async_count)
 979                 return;
 980
 981         /* The async schedule and async_unlink list are supposed to be empty */
 982         WARN_ON(ehci->async->qh_next.qh || ehci->async_unlink);
 983
 984         /* Don't turn off the schedule until ASS is 1 */
 985         ehci_poll_ASS(ehci);
 986 }
 987
 988 /* move qh (and its qtds) onto async queue; maybe enable queue.  */
 989
 990 static void qh_link_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 991 {
 992         __hc32          dma = QH_NEXT(ehci, qh->qh_dma);
 993         struct ehci_qh  *head;
 994
 995         /* Don't link a QH if there's a Clear-TT-Buffer pending */
 996         if (unlikely(qh->clearing_tt))
 997                 return;
 998
 999         WARN_ON(qh->qh_state != QH_STATE_IDLE);
1000
1001         /* clear halt and/or toggle; and maybe recover from silicon quirk */
1002         qh_refresh(ehci, qh);
1003
1004         /* splice right after start */
1005         head = ehci->async;
1006         qh->qh_next = head->qh_next;
1007         qh->hw->hw_next = head->hw->hw_next;
1008         wmb ();
1009
1010         head->qh_next.qh = qh;
1011         head->hw->hw_next = dma;
1012
1013         qh->xacterrs = 0;
1014         qh->qh_state = QH_STATE_LINKED;
1015         /* qtd completions reported later by interrupt */
1016
1017         enable_async(ehci);
1018 }
1019
1020 /*-------------------------------------------------------------------------*/
1021
1022 /*
1023  * For control/bulk/interrupt, return QH with these TDs appended.
1024  * Allocates and initializes the QH if necessary.
1025  * Returns null if it can't allocate a QH it needs to.
1026  * If the QH has TDs (urbs) already, that's great.
1027  */
1028 static struct ehci_qh *qh_append_tds (
1029         struct ehci_hcd         *ehci,
1030         struct urb              *urb,
1031         struct list_head        *qtd_list,
1032         int                     epnum,
1033         void                    **ptr
1034 )
1035 {
1036         struct ehci_qh          *qh = NULL;
1037         __hc32                  qh_addr_mask = cpu_to_hc32(ehci, 0x7f);
1038
1039         qh = (struct ehci_qh *) *ptr;
1040         if (unlikely (qh == NULL)) {
1041                 /* can't sleep here, we have ehci->lock... */
1042                 qh = qh_make (ehci, urb, GFP_ATOMIC);
1043                 *ptr = qh;
1044         }
1045         if (likely (qh != NULL)) {
1046                 struct ehci_qtd *qtd;
1047
1048                 if (unlikely (list_empty (qtd_list)))
1049                         qtd = NULL;
1050                 else
1051                         qtd = list_entry (qtd_list->next, struct ehci_qtd,
1052                                         qtd_list);
1053
1054                 /* control qh may need patching ... */
1055                 if (unlikely (epnum == 0)) {
1056
1057                         /* usb_reset_device() briefly reverts to address 0 */
1058                         if (usb_pipedevice (urb->pipe) == 0)
1059                                 qh->hw->hw_info1 &= ~qh_addr_mask;
1060                 }
1061
1062                 /* just one way to queue requests: swap with the dummy qtd.
1063                  * only hc or qh_refresh() ever modify the overlay.
1064                  */
1065                 if (likely (qtd != NULL)) {
1066                         struct ehci_qtd         *dummy;
1067                         dma_addr_t              dma;
1068                         __hc32                  token;
1069
1070                         /* to avoid racing the HC, use the dummy td instead of
1071                          * the first td of our list (becomes new dummy).  both
1072                          * tds stay deactivated until we're done, when the
1073                          * HC is allowed to fetch the old dummy (4.10.2).
1074                          */
1075                         token = qtd->hw_token;
1076                         qtd->hw_token = HALT_BIT(ehci);
1077
1078                         dummy = qh->dummy;
1079
1080                         dma = dummy->qtd_dma;
1081                         *dummy = *qtd;
1082                         dummy->qtd_dma = dma;
1083
1084                         list_del (&qtd->qtd_list);
1085                         list_add (&dummy->qtd_list, qtd_list);
1086                         list_splice_tail(qtd_list, &qh->qtd_list);
1087
1088                         ehci_qtd_init(ehci, qtd, qtd->qtd_dma);
1089                         qh->dummy = qtd;
1090
1091                         /* hc must see the new dummy at list end */
1092                         dma = qtd->qtd_dma;
1093                         qtd = list_entry (qh->qtd_list.prev,
1094                                         struct ehci_qtd, qtd_list);
1095                         qtd->hw_next = QTD_NEXT(ehci, dma);
1096
1097                         /* let the hc process these next qtds */
1098                         wmb ();
1099                         dummy->hw_token = token;
1100
1101                         urb->hcpriv = qh;
1102                 }
1103         }
1104         return qh;
1105 }
1106
1107 /*-------------------------------------------------------------------------*/
1108
1109 static int
1110 submit_async (
1111         struct ehci_hcd         *ehci,
1112         struct urb              *urb,
1113         struct list_head        *qtd_list,
1114         gfp_t                   mem_flags
1115 ) {
1116         int                     epnum;
1117         unsigned long           flags;
1118         struct ehci_qh          *qh = NULL;
1119         int                     rc;
1120
1121         epnum = urb->ep->desc.bEndpointAddress;
1122
1123 #ifdef EHCI_URB_TRACE
1124         {
1125                 struct ehci_qtd *qtd;
1126                 qtd = list_entry(qtd_list->next, struct ehci_qtd, qtd_list);
1127                 ehci_dbg(ehci,
1128                          "%s %s urb %p ep%d%s len %d, qtd %p [qh %p]\n",
1129                          __func__, urb->dev->devpath, urb,
1130                          epnum & 0x0f, (epnum & USB_DIR_IN) ? "in" : "out",
1131                          urb->transfer_buffer_length,
1132                          qtd, urb->ep->hcpriv);
1133         }
1134 #endif
1135
1136         spin_lock_irqsave (&ehci->lock, flags);
1137         if (unlikely(!HCD_HW_ACCESSIBLE(ehci_to_hcd(ehci)))) {
1138                 rc = -ESHUTDOWN;
1139                 goto done;
1140         }
1141         rc = usb_hcd_link_urb_to_ep(ehci_to_hcd(ehci), urb);
1142         if (unlikely(rc))
1143                 goto done;
1144
1145         qh = qh_append_tds(ehci, urb, qtd_list, epnum, &urb->ep->hcpriv);
1146         if (unlikely(qh == NULL)) {
1147                 usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
1148                 rc = -ENOMEM;
1149                 goto done;
1150         }
1151
1152         /* Control/bulk operations through TTs don't need scheduling,
1153          * the HC and TT handle it when the TT has a buffer ready.
1154          */
1155         if (likely (qh->qh_state == QH_STATE_IDLE))
1156                 qh_link_async(ehci, qh);
1157  done:
1158         spin_unlock_irqrestore (&ehci->lock, flags);
1159         if (unlikely (qh == NULL))
1160                 qtd_list_free (ehci, urb, qtd_list);
1161         return rc;
1162 }
1163
1164 /*-------------------------------------------------------------------------*/
1165
1166 static void single_unlink_async(struct ehci_hcd *ehci, struct ehci_qh *qh)
1167 {
1168         struct ehci_qh          *prev;
1169
1170         /* Add to the end of the list of QHs waiting for the next IAAD */
1171         qh->qh_state = QH_STATE_UNLINK;
1172         if (ehci->async_unlink)
1173                 ehci->async_unlink_last->unlink_next = qh;
1174         else
1175                 ehci->async_unlink = qh;
1176         ehci->async_unlink_last = qh;
1177
1178         /* Unlink it from the schedule */
1179         prev = ehci->async;
1180         while (prev->qh_next.qh != qh)
1181                 prev = prev->qh_next.qh;
1182
1183         prev->hw->hw_next = qh->hw->hw_next;
1184         prev->qh_next = qh->qh_next;
1185         if (ehci->qh_scan_next == qh)
1186                 ehci->qh_scan_next = qh->qh_next.qh;
1187 }
1188
1189 static void start_iaa_cycle(struct ehci_hcd *ehci, bool nested)
1190 {
1191         /*
1192          * Do nothing if an IAA cycle is already running or
1193          * if one will be started shortly.
1194          */
1195         if (ehci->async_iaa || ehci->async_unlinking)
1196                 return;
1197
1198         /* Do all the waiting QHs at once */
1199         ehci->async_iaa = ehci->async_unlink;
1200         ehci->async_unlink = NULL;
1201
1202         /* If the controller isn't running, we don't have to wait for it */
1203         if (unlikely(ehci->rh_state < EHCI_RH_RUNNING)) {
1204                 if (!nested)            /* Avoid recursion */
1205                         end_unlink_async(ehci);
1206
1207         /* Otherwise start a new IAA cycle */
1208         } else if (likely(ehci->rh_state == EHCI_RH_RUNNING)) {
1209                 /* Make sure the unlinks are all visible to the hardware */
1210                 wmb();
1211
1212                 ehci_writel(ehci, ehci->command | CMD_IAAD,
1213                                 &ehci->regs->command);
1214                 ehci_readl(ehci, &ehci->regs->command);
1215                 ehci_enable_event(ehci, EHCI_HRTIMER_IAA_WATCHDOG, true);
1216         }
1217 }
1218
1219 /* the async qh for the qtds being unlinked are now gone from the HC */
1220
1221 static void end_unlink_async(struct ehci_hcd *ehci)
1222 {
1223         struct ehci_qh          *qh;
1224
1225         if (ehci->has_synopsys_hc_bug)
1226                 ehci_writel(ehci, (u32) ehci->async->qh_dma,
1227                             &ehci->regs->async_next);
1228
1229         /* Process the idle QHs */
1230  restart:
1231         ehci->async_unlinking = true;
1232         while (ehci->async_iaa) {
1233                 qh = ehci->async_iaa;
1234                 ehci->async_iaa = qh->unlink_next;
1235                 qh->unlink_next = NULL;
1236
1237                 qh->qh_state = QH_STATE_IDLE;
1238                 qh->qh_next.qh = NULL;
1239
1240                 qh_completions(ehci, qh);
1241                 if (!list_empty(&qh->qtd_list) &&
1242                                 ehci->rh_state == EHCI_RH_RUNNING)
1243                         qh_link_async(ehci, qh);
1244                 disable_async(ehci);
1245         }
1246         ehci->async_unlinking = false;
1247
1248         /* Start a new IAA cycle if any QHs are waiting for it */
1249         if (ehci->async_unlink) {
1250                 start_iaa_cycle(ehci, true);
1251                 if (unlikely(ehci->rh_state < EHCI_RH_RUNNING))
1252                         goto restart;
1253         }
1254 }
1255
1256 static void unlink_empty_async(struct ehci_hcd *ehci)
1257 {
1258         struct ehci_qh          *qh, *next;
1259         bool                    stopped = (ehci->rh_state < EHCI_RH_RUNNING);
1260         bool                    check_unlinks_later = false;
1261
1262         /* Unlink all the async QHs that have been empty for a timer cycle */
1263         next = ehci->async->qh_next.qh;
1264         while (next) {
1265                 qh = next;
1266                 next = qh->qh_next.qh;
1267
1268                 if (list_empty(&qh->qtd_list) &&
1269                                 qh->qh_state == QH_STATE_LINKED) {
1270                         if (!stopped && qh->unlink_cycle ==
1271                                         ehci->async_unlink_cycle)
1272                                 check_unlinks_later = true;
1273                         else
1274                                 single_unlink_async(ehci, qh);
1275                 }
1276         }
1277
1278         /* Start a new IAA cycle if any QHs are waiting for it */
1279         if (ehci->async_unlink)
1280                 start_iaa_cycle(ehci, false);
1281
1282         /* QHs that haven't been empty for long enough will be handled later */
1283         if (check_unlinks_later) {
1284                 ehci_enable_event(ehci, EHCI_HRTIMER_ASYNC_UNLINKS, true);
1285                 ++ehci->async_unlink_cycle;
1286         }
1287 }
1288
1289 /* makes sure the async qh will become idle */
1290 /* caller must own ehci->lock */
1291
1292 static void start_unlink_async(struct ehci_hcd *ehci, struct ehci_qh *qh)
1293 {
1294         /*
1295          * If the QH isn't linked then there's nothing we can do
1296          * unless we were called during a giveback, in which case
1297          * qh_completions() has to deal with it.
1298          */
1299         if (qh->qh_state != QH_STATE_LINKED) {
1300                 if (qh->qh_state == QH_STATE_COMPLETING)
1301                         qh->needs_rescan = 1;
1302                 return;
1303         }
1304
1305         single_unlink_async(ehci, qh);
1306         start_iaa_cycle(ehci, false);
1307 }
1308
1309 /*-------------------------------------------------------------------------*/
1310
1311 static void scan_async (struct ehci_hcd *ehci)
1312 {
1313         struct ehci_qh          *qh;
1314         bool                    check_unlinks_later = false;
1315
1316         ehci->qh_scan_next = ehci->async->qh_next.qh;
1317         while (ehci->qh_scan_next) {
1318                 qh = ehci->qh_scan_next;
1319                 ehci->qh_scan_next = qh->qh_next.qh;
1320  rescan:
1321                 /* clean any finished work for this qh */
1322                 if (!list_empty(&qh->qtd_list)) {
1323                         int temp;
1324
1325                         /*
1326                          * Unlinks could happen here; completion reporting
1327                          * drops the lock.  That's why ehci->qh_scan_next
1328                          * always holds the next qh to scan; if the next qh
1329                          * gets unlinked then ehci->qh_scan_next is adjusted
1330                          * in single_unlink_async().
1331                          */
1332                         temp = qh_completions(ehci, qh);
1333                         if (qh->needs_rescan) {
1334                                 start_unlink_async(ehci, qh);
1335                         } else if (list_empty(&qh->qtd_list)
1336                                         && qh->qh_state == QH_STATE_LINKED) {
1337                                 qh->unlink_cycle = ehci->async_unlink_cycle;
1338                                 check_unlinks_later = true;
1339                         } else if (temp != 0)
1340                                 goto rescan;
1341                 }
1342         }
1343
1344         /*
1345          * Unlink empty entries, reducing DMA usage as well
1346          * as HCD schedule-scanning costs.  Delay for any qh
1347          * we just scanned, there's a not-unusual case that it
1348          * doesn't stay idle for long.
1349          */
1350         if (check_unlinks_later && ehci->rh_state == EHCI_RH_RUNNING &&
1351                         !(ehci->enabled_hrtimer_events &
1352                                 BIT(EHCI_HRTIMER_ASYNC_UNLINKS))) {
1353                 ehci_enable_event(ehci, EHCI_HRTIMER_ASYNC_UNLINKS, true);
1354                 ++ehci->async_unlink_cycle;
1355         }
1356 }