SAFE public projects git trees. - safe/jmp/linux-2.6/blob - drivers/usb/host/ehci-q.c

   1 /*
   2  * Copyright (C) 2001-2004 by David Brownell
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License as published by the
   6  * Free Software Foundation; either version 2 of the License, or (at your
   7  * option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  11  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software Foundation,
  16  * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 /* this file is part of ehci-hcd.c */
  20
  21 /*-------------------------------------------------------------------------*/
  22
  23 /*
  24  * EHCI hardware queue manipulation ... the core.  QH/QTD manipulation.
  25  *
  26  * Control, bulk, and interrupt traffic all use "qh" lists.  They list "qtd"
  27  * entries describing USB transactions, max 16-20kB/entry (with 4kB-aligned
  28  * buffers needed for the larger number).  We use one QH per endpoint, queue
  29  * multiple urbs (all three types) per endpoint.  URBs may need several qtds.
  30  *
  31  * ISO traffic uses "ISO TD" (itd, and sitd) records, and (along with
  32  * interrupts) needs careful scheduling.  Performance improvements can be
  33  * an ongoing challenge.  That's in "ehci-sched.c".
  34  *
  35  * USB 1.1 devices are handled (a) by "companion" OHCI or UHCI root hubs,
  36  * or otherwise through transaction translators (TTs) in USB 2.0 hubs using
  37  * (b) special fields in qh entries or (c) split iso entries.  TTs will
  38  * buffer low/full speed data so the host collects it at high speed.
  39  */
  40
  41 /*-------------------------------------------------------------------------*/
  42
  43 /* fill a qtd, returning how much of the buffer we were able to queue up */
  44
  45 static int
  46 qtd_fill(struct ehci_hcd *ehci, struct ehci_qtd *qtd, dma_addr_t buf,
  47                   size_t len, int token, int maxpacket)
  48 {
  49         int     i, count;
  50         u64     addr = buf;
  51
  52         /* one buffer entry per 4K ... first might be short or unaligned */
  53         qtd->hw_buf[0] = cpu_to_hc32(ehci, (u32)addr);
  54         qtd->hw_buf_hi[0] = cpu_to_hc32(ehci, (u32)(addr >> 32));
  55         count = 0x1000 - (buf & 0x0fff);        /* rest of that page */
  56         if (likely (len < count))               /* ... iff needed */
  57                 count = len;
  58         else {
  59                 buf +=  0x1000;
  60                 buf &= ~0x0fff;
  61
  62                 /* per-qtd limit: from 16K to 20K (best alignment) */
  63                 for (i = 1; count < len && i < 5; i++) {
  64                         addr = buf;
  65                         qtd->hw_buf[i] = cpu_to_hc32(ehci, (u32)addr);
  66                         qtd->hw_buf_hi[i] = cpu_to_hc32(ehci,
  67                                         (u32)(addr >> 32));
  68                         buf += 0x1000;
  69                         if ((count + 0x1000) < len)
  70                                 count += 0x1000;
  71                         else
  72                                 count = len;
  73                 }
  74
  75                 /* short packets may only terminate transfers */
  76                 if (count != len)
  77                         count -= (count % maxpacket);
  78         }
  79         qtd->hw_token = cpu_to_hc32(ehci, (count << 16) | token);
  80         qtd->length = count;
  81
  82         return count;
  83 }
  84
  85 /*-------------------------------------------------------------------------*/
  86
  87 static inline void
  88 qh_update (struct ehci_hcd *ehci, struct ehci_qh *qh, struct ehci_qtd *qtd)
  89 {
  90         struct ehci_qh_hw *hw = qh->hw;
  91
  92         /* writes to an active overlay are unsafe */
  93         BUG_ON(qh->qh_state != QH_STATE_IDLE);
  94
  95         hw->hw_qtd_next = QTD_NEXT(ehci, qtd->qtd_dma);
  96         hw->hw_alt_next = EHCI_LIST_END(ehci);
  97
  98         /* Except for control endpoints, we make hardware maintain data
  99          * toggle (like OHCI) ... here (re)initialize the toggle in the QH,
 100          * and set the pseudo-toggle in udev. Only usb_clear_halt() will
 101          * ever clear it.
 102          */
 103         if (!(hw->hw_info1 & cpu_to_hc32(ehci, 1 << 14))) {
 104                 unsigned        is_out, epnum;
 105
 106                 is_out = !(qtd->hw_token & cpu_to_hc32(ehci, 1 << 8));
 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         /* HC must see latest qtd and qh data before we clear ACTIVE+HALT */
 115         wmb ();
 116         hw->hw_token &= cpu_to_hc32(ehci, QTD_TOGGLE | QTD_STS_PING);
 117 }
 118
 119 /* if it weren't for a common silicon quirk (writing the dummy into the qh
 120  * overlay, so qh->hw_token wrongly becomes inactive/halted), only fault
 121  * recovery (including urb dequeue) would need software changes to a QH...
 122  */
 123 static void
 124 qh_refresh (struct ehci_hcd *ehci, struct ehci_qh *qh)
 125 {
 126         struct ehci_qtd *qtd;
 127
 128         if (list_empty (&qh->qtd_list))
 129                 qtd = qh->dummy;
 130         else {
 131                 qtd = list_entry (qh->qtd_list.next,
 132                                 struct ehci_qtd, qtd_list);
 133                 /* first qtd may already be partially processed */
 134                 if (cpu_to_hc32(ehci, qtd->qtd_dma) == qh->hw->hw_current)
 135                         qtd = NULL;
 136         }
 137
 138         if (qtd)
 139                 qh_update (ehci, qh, qtd);
 140 }
 141
 142 /*-------------------------------------------------------------------------*/
 143
 144 static void qh_link_async(struct ehci_hcd *ehci, struct ehci_qh *qh);
 145
 146 static void ehci_clear_tt_buffer_complete(struct usb_hcd *hcd,
 147                 struct usb_host_endpoint *ep)
 148 {
 149         struct ehci_hcd         *ehci = hcd_to_ehci(hcd);
 150         struct ehci_qh          *qh = ep->hcpriv;
 151         unsigned long           flags;
 152
 153         spin_lock_irqsave(&ehci->lock, flags);
 154         qh->clearing_tt = 0;
 155         if (qh->qh_state == QH_STATE_IDLE && !list_empty(&qh->qtd_list)
 156                         && HC_IS_RUNNING(hcd->state))
 157                 qh_link_async(ehci, qh);
 158         spin_unlock_irqrestore(&ehci->lock, flags);
 159 }
 160
 161 static void ehci_clear_tt_buffer(struct ehci_hcd *ehci, struct ehci_qh *qh,
 162                 struct urb *urb, u32 token)
 163 {
 164
 165         /* If an async split transaction gets an error or is unlinked,
 166          * the TT buffer may be left in an indeterminate state.  We
 167          * have to clear the TT buffer.
 168          *
 169          * Note: this routine is never called for Isochronous transfers.
 170          */
 171         if (urb->dev->tt && !usb_pipeint(urb->pipe) && !qh->clearing_tt) {
 172 #ifdef DEBUG
 173                 struct usb_device *tt = urb->dev->tt->hub;
 174                 dev_dbg(&tt->dev,
 175                         "clear tt buffer port %d, a%d ep%d t%08x\n",
 176                         urb->dev->ttport, urb->dev->devnum,
 177                         usb_pipeendpoint(urb->pipe), token);
 178 #endif /* DEBUG */
 179                 if (!ehci_is_TDI(ehci)
 180                                 || urb->dev->tt->hub !=
 181                                    ehci_to_hcd(ehci)->self.root_hub) {
 182                         if (usb_hub_clear_tt_buffer(urb) == 0)
 183                                 qh->clearing_tt = 1;
 184                 } else {
 185
 186                         /* REVISIT ARC-derived cores don't clear the root
 187                          * hub TT buffer in this way...
 188                          */
 189                 }
 190         }
 191 }
 192
 193 static int qtd_copy_status (
 194         struct ehci_hcd *ehci,
 195         struct urb *urb,
 196         size_t length,
 197         u32 token
 198 )
 199 {
 200         int     status = -EINPROGRESS;
 201
 202         /* count IN/OUT bytes, not SETUP (even short packets) */
 203         if (likely (QTD_PID (token) != 2))
 204                 urb->actual_length += length - QTD_LENGTH (token);
 205
 206         /* don't modify error codes */
 207         if (unlikely(urb->unlinked))
 208                 return status;
 209
 210         /* force cleanup after short read; not always an error */
 211         if (unlikely (IS_SHORT_READ (token)))
 212                 status = -EREMOTEIO;
 213
 214         /* serious "can't proceed" faults reported by the hardware */
 215         if (token & QTD_STS_HALT) {
 216                 if (token & QTD_STS_BABBLE) {
 217                         /* FIXME "must" disable babbling device's port too */
 218                         status = -EOVERFLOW;
 219                 /* CERR nonzero + halt --> stall */
 220                 } else if (QTD_CERR(token)) {
 221                         status = -EPIPE;
 222
 223                 /* In theory, more than one of the following bits can be set
 224                  * since they are sticky and the transaction is retried.
 225                  * Which to test first is rather arbitrary.
 226                  */
 227                 } else if (token & QTD_STS_MMF) {
 228                         /* fs/ls interrupt xfer missed the complete-split */
 229                         status = -EPROTO;
 230                 } else if (token & QTD_STS_DBE) {
 231                         status = (QTD_PID (token) == 1) /* IN ? */
 232                                 ? -ENOSR  /* hc couldn't read data */
 233                                 : -ECOMM; /* hc couldn't write data */
 234                 } else if (token & QTD_STS_XACT) {
 235                         /* timeout, bad CRC, wrong PID, etc */
 236                         ehci_dbg(ehci, "devpath %s ep%d%s 3strikes\n",
 237                                 urb->dev->devpath,
 238                                 usb_pipeendpoint(urb->pipe),
 239                                 usb_pipein(urb->pipe) ? "in" : "out");
 240                         status = -EPROTO;
 241                 } else {        /* unknown */
 242                         status = -EPROTO;
 243                 }
 244
 245                 ehci_vdbg (ehci,
 246                         "dev%d ep%d%s qtd token %08x --> status %d\n",
 247                         usb_pipedevice (urb->pipe),
 248                         usb_pipeendpoint (urb->pipe),
 249                         usb_pipein (urb->pipe) ? "in" : "out",
 250                         token, status);
 251         }
 252
 253         return status;
 254 }
 255
 256 static void
 257 ehci_urb_done(struct ehci_hcd *ehci, struct urb *urb, int status)
 258 __releases(ehci->lock)
 259 __acquires(ehci->lock)
 260 {
 261         if (likely (urb->hcpriv != NULL)) {
 262                 struct ehci_qh  *qh = (struct ehci_qh *) urb->hcpriv;
 263
 264                 /* S-mask in a QH means it's an interrupt urb */
 265                 if ((qh->hw->hw_info2 & cpu_to_hc32(ehci, QH_SMASK)) != 0) {
 266
 267                         /* ... update hc-wide periodic stats (for usbfs) */
 268                         ehci_to_hcd(ehci)->self.bandwidth_int_reqs--;
 269                 }
 270                 qh_put (qh);
 271         }
 272
 273         if (unlikely(urb->unlinked)) {
 274                 COUNT(ehci->stats.unlink);
 275         } else {
 276                 /* report non-error and short read status as zero */
 277                 if (status == -EINPROGRESS || status == -EREMOTEIO)
 278                         status = 0;
 279                 COUNT(ehci->stats.complete);
 280         }
 281
 282 #ifdef EHCI_URB_TRACE
 283         ehci_dbg (ehci,
 284                 "%s %s urb %p ep%d%s status %d len %d/%d\n",
 285                 __func__, urb->dev->devpath, urb,
 286                 usb_pipeendpoint (urb->pipe),
 287                 usb_pipein (urb->pipe) ? "in" : "out",
 288                 status,
 289                 urb->actual_length, urb->transfer_buffer_length);
 290 #endif
 291
 292         /* complete() can reenter this HCD */
 293         usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
 294         spin_unlock (&ehci->lock);
 295         usb_hcd_giveback_urb(ehci_to_hcd(ehci), urb, status);
 296         spin_lock (&ehci->lock);
 297 }
 298
 299 static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh);
 300 static void unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh);
 301
 302 static int qh_schedule (struct ehci_hcd *ehci, struct ehci_qh *qh);
 303
 304 /*
 305  * Process and free completed qtds for a qh, returning URBs to drivers.
 306  * Chases up to qh->hw_current.  Returns number of completions called,
 307  * indicating how much "real" work we did.
 308  */
 309 static unsigned
 310 qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
 311 {
 312         struct ehci_qtd         *last, *end = qh->dummy;
 313         struct list_head        *entry, *tmp;
 314         int                     last_status;
 315         int                     stopped;
 316         unsigned                count = 0;
 317         u8                      state;
 318         const __le32            halt = HALT_BIT(ehci);
 319         struct ehci_qh_hw       *hw = qh->hw;
 320
 321         if (unlikely (list_empty (&qh->qtd_list)))
 322                 return count;
 323
 324         /* completions (or tasks on other cpus) must never clobber HALT
 325          * till we've gone through and cleaned everything up, even when
 326          * they add urbs to this qh's queue or mark them for unlinking.
 327          *
 328          * NOTE:  unlinking expects to be done in queue order.
 329          *
 330          * It's a bug for qh->qh_state to be anything other than
 331          * QH_STATE_IDLE, unless our caller is scan_async() or
 332          * scan_periodic().
 333          */
 334         state = qh->qh_state;
 335         qh->qh_state = QH_STATE_COMPLETING;
 336         stopped = (state == QH_STATE_IDLE);
 337
 338  rescan:
 339         last = NULL;
 340         last_status = -EINPROGRESS;
 341         qh->needs_rescan = 0;
 342
 343         /* remove de-activated QTDs from front of queue.
 344          * after faults (including short reads), cleanup this urb
 345          * then let the queue advance.
 346          * if queue is stopped, handles unlinks.
 347          */
 348         list_for_each_safe (entry, tmp, &qh->qtd_list) {
 349                 struct ehci_qtd *qtd;
 350                 struct urb      *urb;
 351                 u32             token = 0;
 352
 353                 qtd = list_entry (entry, struct ehci_qtd, qtd_list);
 354                 urb = qtd->urb;
 355
 356                 /* clean up any state from previous QTD ...*/
 357                 if (last) {
 358                         if (likely (last->urb != urb)) {
 359                                 ehci_urb_done(ehci, last->urb, last_status);
 360                                 count++;
 361                                 last_status = -EINPROGRESS;
 362                         }
 363                         ehci_qtd_free (ehci, last);
 364                         last = NULL;
 365                 }
 366
 367                 /* ignore urbs submitted during completions we reported */
 368                 if (qtd == end)
 369                         break;
 370
 371                 /* hardware copies qtd out of qh overlay */
 372                 rmb ();
 373                 token = hc32_to_cpu(ehci, qtd->hw_token);
 374
 375                 /* always clean up qtds the hc de-activated */
 376  retry_xacterr:
 377                 if ((token & QTD_STS_ACTIVE) == 0) {
 378
 379                         /* on STALL, error, and short reads this urb must
 380                          * complete and all its qtds must be recycled.
 381                          */
 382                         if ((token & QTD_STS_HALT) != 0) {
 383
 384                                 /* retry transaction errors until we
 385                                  * reach the software xacterr limit
 386                                  */
 387                                 if ((token & QTD_STS_XACT) &&
 388                                                 QTD_CERR(token) == 0 &&
 389                                                 ++qh->xacterrs < QH_XACTERR_MAX &&
 390                                                 !urb->unlinked) {
 391                                         ehci_dbg(ehci,
 392         "detected XactErr len %zu/%zu retry %d\n",
 393         qtd->length - QTD_LENGTH(token), qtd->length, qh->xacterrs);
 394
 395                                         /* reset the token in the qtd and the
 396                                          * qh overlay (which still contains
 397                                          * the qtd) so that we pick up from
 398                                          * where we left off
 399                                          */
 400                                         token &= ~QTD_STS_HALT;
 401                                         token |= QTD_STS_ACTIVE |
 402                                                         (EHCI_TUNE_CERR << 10);
 403                                         qtd->hw_token = cpu_to_hc32(ehci,
 404                                                         token);
 405                                         wmb();
 406                                         hw->hw_token = cpu_to_hc32(ehci,
 407                                                         token);
 408                                         goto retry_xacterr;
 409                                 }
 410                                 stopped = 1;
 411
 412                         /* magic dummy for some short reads; qh won't advance.
 413                          * that silicon quirk can kick in with this dummy too.
 414                          *
 415                          * other short reads won't stop the queue, including
 416                          * control transfers (status stage handles that) or
 417                          * most other single-qtd reads ... the queue stops if
 418                          * URB_SHORT_NOT_OK was set so the driver submitting
 419                          * the urbs could clean it up.
 420                          */
 421                         } else if (IS_SHORT_READ (token)
 422                                         && !(qtd->hw_alt_next
 423                                                 & EHCI_LIST_END(ehci))) {
 424                                 stopped = 1;
 425                                 goto halt;
 426                         }
 427
 428                 /* stop scanning when we reach qtds the hc is using */
 429                 } else if (likely (!stopped
 430                                 && HC_IS_RUNNING (ehci_to_hcd(ehci)->state))) {
 431                         break;
 432
 433                 /* scan the whole queue for unlinks whenever it stops */
 434                 } else {
 435                         stopped = 1;
 436
 437                         /* cancel everything if we halt, suspend, etc */
 438                         if (!HC_IS_RUNNING(ehci_to_hcd(ehci)->state))
 439                                 last_status = -ESHUTDOWN;
 440
 441                         /* this qtd is active; skip it unless a previous qtd
 442                          * for its urb faulted, or its urb was canceled.
 443                          */
 444                         else if (last_status == -EINPROGRESS && !urb->unlinked)
 445                                 continue;
 446
 447                         /* qh unlinked; token in overlay may be most current */
 448                         if (state == QH_STATE_IDLE
 449                                         && cpu_to_hc32(ehci, qtd->qtd_dma)
 450                                                 == hw->hw_current) {
 451                                 token = hc32_to_cpu(ehci, hw->hw_token);
 452
 453                                 /* An unlink may leave an incomplete
 454                                  * async transaction in the TT buffer.
 455                                  * We have to clear it.
 456                                  */
 457                                 ehci_clear_tt_buffer(ehci, qh, urb, token);
 458                         }
 459
 460                         /* force halt for unlinked or blocked qh, so we'll
 461                          * patch the qh later and so that completions can't
 462                          * activate it while we "know" it's stopped.
 463                          */
 464                         if ((halt & hw->hw_token) == 0) {
 465 halt:
 466                                 hw->hw_token |= halt;
 467                                 wmb ();
 468                         }
 469                 }
 470
 471                 /* unless we already know the urb's status, collect qtd status
 472                  * and update count of bytes transferred.  in common short read
 473                  * cases with only one data qtd (including control transfers),
 474                  * queue processing won't halt.  but with two or more qtds (for
 475                  * example, with a 32 KB transfer), when the first qtd gets a
 476                  * short read the second must be removed by hand.
 477                  */
 478                 if (last_status == -EINPROGRESS) {
 479                         last_status = qtd_copy_status(ehci, urb,
 480                                         qtd->length, token);
 481                         if (last_status == -EREMOTEIO
 482                                         && (qtd->hw_alt_next
 483                                                 & EHCI_LIST_END(ehci)))
 484                                 last_status = -EINPROGRESS;
 485
 486                         /* As part of low/full-speed endpoint-halt processing
 487                          * we must clear the TT buffer (11.17.5).
 488                          */
 489                         if (unlikely(last_status != -EINPROGRESS &&
 490                                         last_status != -EREMOTEIO)) {
 491                                 /* The TT's in some hubs malfunction when they
 492                                  * receive this request following a STALL (they
 493                                  * stop sending isochronous packets).  Since a
 494                                  * STALL can't leave the TT buffer in a busy
 495                                  * state (if you believe Figures 11-48 - 11-51
 496                                  * in the USB 2.0 spec), we won't clear the TT
 497                                  * buffer in this case.  Strictly speaking this
 498                                  * is a violation of the spec.
 499                                  */
 500                                 if (last_status != -EPIPE)
 501                                         ehci_clear_tt_buffer(ehci, qh, urb,
 502                                                         token);
 503                         }
 504                 }
 505
 506                 /* if we're removing something not at the queue head,
 507                  * patch the hardware queue pointer.
 508                  */
 509                 if (stopped && qtd->qtd_list.prev != &qh->qtd_list) {
 510                         last = list_entry (qtd->qtd_list.prev,
 511                                         struct ehci_qtd, qtd_list);
 512                         last->hw_next = qtd->hw_next;
 513                 }
 514
 515                 /* remove qtd; it's recycled after possible urb completion */
 516                 list_del (&qtd->qtd_list);
 517                 last = qtd;
 518
 519                 /* reinit the xacterr counter for the next qtd */
 520                 qh->xacterrs = 0;
 521         }
 522
 523         /* last urb's completion might still need calling */
 524         if (likely (last != NULL)) {
 525                 ehci_urb_done(ehci, last->urb, last_status);
 526                 count++;
 527                 ehci_qtd_free (ehci, last);
 528         }
 529
 530         /* Do we need to rescan for URBs dequeued during a giveback? */
 531         if (unlikely(qh->needs_rescan)) {
 532                 /* If the QH is already unlinked, do the rescan now. */
 533                 if (state == QH_STATE_IDLE)
 534                         goto rescan;
 535
 536                 /* Otherwise we have to wait until the QH is fully unlinked.
 537                  * Our caller will start an unlink if qh->needs_rescan is
 538                  * set.  But if an unlink has already started, nothing needs
 539                  * to be done.
 540                  */
 541                 if (state != QH_STATE_LINKED)
 542                         qh->needs_rescan = 0;
 543         }
 544
 545         /* restore original state; caller must unlink or relink */
 546         qh->qh_state = state;
 547
 548         /* be sure the hardware's done with the qh before refreshing
 549          * it after fault cleanup, or recovering from silicon wrongly
 550          * overlaying the dummy qtd (which reduces DMA chatter).
 551          */
 552         if (stopped != 0 || hw->hw_qtd_next == EHCI_LIST_END(ehci)) {
 553                 switch (state) {
 554                 case QH_STATE_IDLE:
 555                         qh_refresh(ehci, qh);
 556                         break;
 557                 case QH_STATE_LINKED:
 558                         /* We won't refresh a QH that's linked (after the HC
 559                          * stopped the queue).  That avoids a race:
 560                          *  - HC reads first part of QH;
 561                          *  - CPU updates that first part and the token;
 562                          *  - HC reads rest of that QH, including token
 563                          * Result:  HC gets an inconsistent image, and then
 564                          * DMAs to/from the wrong memory (corrupting it).
 565                          *
 566                          * That should be rare for interrupt transfers,
 567                          * except maybe high bandwidth ...
 568                          */
 569
 570                         /* Tell the caller to start an unlink */
 571                         qh->needs_rescan = 1;
 572                         break;
 573                 /* otherwise, unlink already started */
 574                 }
 575         }
 576
 577         return count;
 578 }
 579
 580 /*-------------------------------------------------------------------------*/
 581
 582 // high bandwidth multiplier, as encoded in highspeed endpoint descriptors
 583 #define hb_mult(wMaxPacketSize) (1 + (((wMaxPacketSize) >> 11) & 0x03))
 584 // ... and packet size, for any kind of endpoint descriptor
 585 #define max_packet(wMaxPacketSize) ((wMaxPacketSize) & 0x07ff)
 586
 587 /*
 588  * reverse of qh_urb_transaction:  free a list of TDs.
 589  * used for cleanup after errors, before HC sees an URB's TDs.
 590  */
 591 static void qtd_list_free (
 592         struct ehci_hcd         *ehci,
 593         struct urb              *urb,
 594         struct list_head        *qtd_list
 595 ) {
 596         struct list_head        *entry, *temp;
 597
 598         list_for_each_safe (entry, temp, qtd_list) {
 599                 struct ehci_qtd *qtd;
 600
 601                 qtd = list_entry (entry, struct ehci_qtd, qtd_list);
 602                 list_del (&qtd->qtd_list);
 603                 ehci_qtd_free (ehci, qtd);
 604         }
 605 }
 606
 607 /*
 608  * create a list of filled qtds for this URB; won't link into qh.
 609  */
 610 static struct list_head *
 611 qh_urb_transaction (
 612         struct ehci_hcd         *ehci,
 613         struct urb              *urb,
 614         struct list_head        *head,
 615         gfp_t                   flags
 616 ) {
 617         struct ehci_qtd         *qtd, *qtd_prev;
 618         dma_addr_t              buf;
 619         int                     len, maxpacket;
 620         int                     is_input;
 621         u32                     token;
 622
 623         /*
 624          * URBs map to sequences of QTDs:  one logical transaction
 625          */
 626         qtd = ehci_qtd_alloc (ehci, flags);
 627         if (unlikely (!qtd))
 628                 return NULL;
 629         list_add_tail (&qtd->qtd_list, head);
 630         qtd->urb = urb;
 631
 632         token = QTD_STS_ACTIVE;
 633         token |= (EHCI_TUNE_CERR << 10);
 634         /* for split transactions, SplitXState initialized to zero */
 635
 636         len = urb->transfer_buffer_length;
 637         is_input = usb_pipein (urb->pipe);
 638         if (usb_pipecontrol (urb->pipe)) {
 639                 /* SETUP pid */
 640                 qtd_fill(ehci, qtd, urb->setup_dma,
 641                                 sizeof (struct usb_ctrlrequest),
 642                                 token | (2 /* "setup" */ << 8), 8);
 643
 644                 /* ... and always at least one more pid */
 645                 token ^= QTD_TOGGLE;
 646                 qtd_prev = qtd;
 647                 qtd = ehci_qtd_alloc (ehci, flags);
 648                 if (unlikely (!qtd))
 649                         goto cleanup;
 650                 qtd->urb = urb;
 651                 qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 652                 list_add_tail (&qtd->qtd_list, head);
 653
 654                 /* for zero length DATA stages, STATUS is always IN */
 655                 if (len == 0)
 656                         token |= (1 /* "in" */ << 8);
 657         }
 658
 659         /*
 660          * data transfer stage:  buffer setup
 661          */
 662         buf = urb->transfer_dma;
 663
 664         if (is_input)
 665                 token |= (1 /* "in" */ << 8);
 666         /* else it's already initted to "out" pid (0 << 8) */
 667
 668         maxpacket = max_packet(usb_maxpacket(urb->dev, urb->pipe, !is_input));
 669
 670         /*
 671          * buffer gets wrapped in one or more qtds;
 672          * last one may be "short" (including zero len)
 673          * and may serve as a control status ack
 674          */
 675         for (;;) {
 676                 int this_qtd_len;
 677
 678                 this_qtd_len = qtd_fill(ehci, qtd, buf, len, token, maxpacket);
 679                 len -= this_qtd_len;
 680                 buf += this_qtd_len;
 681
 682                 /*
 683                  * short reads advance to a "magic" dummy instead of the next
 684                  * qtd ... that forces the queue to stop, for manual cleanup.
 685                  * (this will usually be overridden later.)
 686                  */
 687                 if (is_input)
 688                         qtd->hw_alt_next = ehci->async->hw->hw_alt_next;
 689
 690                 /* qh makes control packets use qtd toggle; maybe switch it */
 691                 if ((maxpacket & (this_qtd_len + (maxpacket - 1))) == 0)
 692                         token ^= QTD_TOGGLE;
 693
 694                 if (likely (len <= 0))
 695                         break;
 696
 697                 qtd_prev = qtd;
 698                 qtd = ehci_qtd_alloc (ehci, flags);
 699                 if (unlikely (!qtd))
 700                         goto cleanup;
 701                 qtd->urb = urb;
 702                 qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 703                 list_add_tail (&qtd->qtd_list, head);
 704         }
 705
 706         /*
 707          * unless the caller requires manual cleanup after short reads,
 708          * have the alt_next mechanism keep the queue running after the
 709          * last data qtd (the only one, for control and most other cases).
 710          */
 711         if (likely ((urb->transfer_flags & URB_SHORT_NOT_OK) == 0
 712                                 || usb_pipecontrol (urb->pipe)))
 713                 qtd->hw_alt_next = EHCI_LIST_END(ehci);
 714
 715         /*
 716          * control requests may need a terminating data "status" ack;
 717          * bulk ones may need a terminating short packet (zero length).
 718          */
 719         if (likely (urb->transfer_buffer_length != 0)) {
 720                 int     one_more = 0;
 721
 722                 if (usb_pipecontrol (urb->pipe)) {
 723                         one_more = 1;
 724                         token ^= 0x0100;        /* "in" <--> "out"  */
 725                         token |= QTD_TOGGLE;    /* force DATA1 */
 726                 } else if (usb_pipebulk (urb->pipe)
 727                                 && (urb->transfer_flags & URB_ZERO_PACKET)
 728                                 && !(urb->transfer_buffer_length % maxpacket)) {
 729                         one_more = 1;
 730                 }
 731                 if (one_more) {
 732                         qtd_prev = qtd;
 733                         qtd = ehci_qtd_alloc (ehci, flags);
 734                         if (unlikely (!qtd))
 735                                 goto cleanup;
 736                         qtd->urb = urb;
 737                         qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 738                         list_add_tail (&qtd->qtd_list, head);
 739
 740                         /* never any data in such packets */
 741                         qtd_fill(ehci, qtd, 0, 0, token, 0);
 742                 }
 743         }
 744
 745         /* by default, enable interrupt on urb completion */
 746         if (likely (!(urb->transfer_flags & URB_NO_INTERRUPT)))
 747                 qtd->hw_token |= cpu_to_hc32(ehci, QTD_IOC);
 748         return head;
 749
 750 cleanup:
 751         qtd_list_free (ehci, urb, head);
 752         return NULL;
 753 }
 754
 755 /*-------------------------------------------------------------------------*/
 756
 757 // Would be best to create all qh's from config descriptors,
 758 // when each interface/altsetting is established.  Unlink
 759 // any previous qh and cancel its urbs first; endpoints are
 760 // implicitly reset then (data toggle too).
 761 // That'd mean updating how usbcore talks to HCDs. (2.7?)
 762
 763
 764 /*
 765  * Each QH holds a qtd list; a QH is used for everything except iso.
 766  *
 767  * For interrupt urbs, the scheduler must set the microframe scheduling
 768  * mask(s) each time the QH gets scheduled.  For highspeed, that's
 769  * just one microframe in the s-mask.  For split interrupt transactions
 770  * there are additional complications: c-mask, maybe FSTNs.
 771  */
 772 static struct ehci_qh *
 773 qh_make (
 774         struct ehci_hcd         *ehci,
 775         struct urb              *urb,
 776         gfp_t                   flags
 777 ) {
 778         struct ehci_qh          *qh = ehci_qh_alloc (ehci, flags);
 779         u32                     info1 = 0, info2 = 0;
 780         int                     is_input, type;
 781         int                     maxp = 0;
 782         struct usb_tt           *tt = urb->dev->tt;
 783         struct ehci_qh_hw       *hw;
 784
 785         if (!qh)
 786                 return qh;
 787
 788         /*
 789          * init endpoint/device data for this QH
 790          */
 791         info1 |= usb_pipeendpoint (urb->pipe) << 8;
 792         info1 |= usb_pipedevice (urb->pipe) << 0;
 793
 794         is_input = usb_pipein (urb->pipe);
 795         type = usb_pipetype (urb->pipe);
 796         maxp = usb_maxpacket (urb->dev, urb->pipe, !is_input);
 797
 798         /* 1024 byte maxpacket is a hardware ceiling.  High bandwidth
 799          * acts like up to 3KB, but is built from smaller packets.
 800          */
 801         if (max_packet(maxp) > 1024) {
 802                 ehci_dbg(ehci, "bogus qh maxpacket %d\n", max_packet(maxp));
 803                 goto done;
 804         }
 805
 806         /* Compute interrupt scheduling parameters just once, and save.
 807          * - allowing for high bandwidth, how many nsec/uframe are used?
 808          * - split transactions need a second CSPLIT uframe; same question
 809          * - splits also need a schedule gap (for full/low speed I/O)
 810          * - qh has a polling interval
 811          *
 812          * For control/bulk requests, the HC or TT handles these.
 813          */
 814         if (type == PIPE_INTERRUPT) {
 815                 qh->usecs = NS_TO_US(usb_calc_bus_time(USB_SPEED_HIGH,
 816                                 is_input, 0,
 817                                 hb_mult(maxp) * max_packet(maxp)));
 818                 qh->start = NO_FRAME;
 819
 820                 if (urb->dev->speed == USB_SPEED_HIGH) {
 821                         qh->c_usecs = 0;
 822                         qh->gap_uf = 0;
 823
 824                         qh->period = urb->interval >> 3;
 825                         if (qh->period == 0 && urb->interval != 1) {
 826                                 /* NOTE interval 2 or 4 uframes could work.
 827                                  * But interval 1 scheduling is simpler, and
 828                                  * includes high bandwidth.
 829                                  */
 830                                 dbg ("intr period %d uframes, NYET!",
 831                                                 urb->interval);
 832                                 goto done;
 833                         }
 834                 } else {
 835                         int             think_time;
 836
 837                         /* gap is f(FS/LS transfer times) */
 838                         qh->gap_uf = 1 + usb_calc_bus_time (urb->dev->speed,
 839                                         is_input, 0, maxp) / (125 * 1000);
 840
 841                         /* FIXME this just approximates SPLIT/CSPLIT times */
 842                         if (is_input) {         // SPLIT, gap, CSPLIT+DATA
 843                                 qh->c_usecs = qh->usecs + HS_USECS (0);
 844                                 qh->usecs = HS_USECS (1);
 845                         } else {                // SPLIT+DATA, gap, CSPLIT
 846                                 qh->usecs += HS_USECS (1);
 847                                 qh->c_usecs = HS_USECS (0);
 848                         }
 849
 850                         think_time = tt ? tt->think_time : 0;
 851                         qh->tt_usecs = NS_TO_US (think_time +
 852                                         usb_calc_bus_time (urb->dev->speed,
 853                                         is_input, 0, max_packet (maxp)));
 854                         qh->period = urb->interval;
 855                 }
 856         }
 857
 858         /* support for tt scheduling, and access to toggles */
 859         qh->dev = urb->dev;
 860
 861         /* using TT? */
 862         switch (urb->dev->speed) {
 863         case USB_SPEED_LOW:
 864                 info1 |= (1 << 12);     /* EPS "low" */
 865                 /* FALL THROUGH */
 866
 867         case USB_SPEED_FULL:
 868                 /* EPS 0 means "full" */
 869                 if (type != PIPE_INTERRUPT)
 870                         info1 |= (EHCI_TUNE_RL_TT << 28);
 871                 if (type == PIPE_CONTROL) {
 872                         info1 |= (1 << 27);     /* for TT */
 873                         info1 |= 1 << 14;       /* toggle from qtd */
 874                 }
 875                 info1 |= maxp << 16;
 876
 877                 info2 |= (EHCI_TUNE_MULT_TT << 30);
 878
 879                 /* Some Freescale processors have an erratum in which the
 880                  * port number in the queue head was 0..N-1 instead of 1..N.
 881                  */
 882                 if (ehci_has_fsl_portno_bug(ehci))
 883                         info2 |= (urb->dev->ttport-1) << 23;
 884                 else
 885                         info2 |= urb->dev->ttport << 23;
 886
 887                 /* set the address of the TT; for TDI's integrated
 888                  * root hub tt, leave it zeroed.
 889                  */
 890                 if (tt && tt->hub != ehci_to_hcd(ehci)->self.root_hub)
 891                         info2 |= tt->hub->devnum << 16;
 892
 893                 /* NOTE:  if (PIPE_INTERRUPT) { scheduler sets c-mask } */
 894
 895                 break;
 896
 897         case USB_SPEED_HIGH:            /* no TT involved */
 898                 info1 |= (2 << 12);     /* EPS "high" */
 899                 if (type == PIPE_CONTROL) {
 900                         info1 |= (EHCI_TUNE_RL_HS << 28);
 901                         info1 |= 64 << 16;      /* usb2 fixed maxpacket */
 902                         info1 |= 1 << 14;       /* toggle from qtd */
 903                         info2 |= (EHCI_TUNE_MULT_HS << 30);
 904                 } else if (type == PIPE_BULK) {
 905                         info1 |= (EHCI_TUNE_RL_HS << 28);
 906                         /* The USB spec says that high speed bulk endpoints
 907                          * always use 512 byte maxpacket.  But some device
 908                          * vendors decided to ignore that, and MSFT is happy
 909                          * to help them do so.  So now people expect to use
 910                          * such nonconformant devices with Linux too; sigh.
 911                          */
 912                         info1 |= max_packet(maxp) << 16;
 913                         info2 |= (EHCI_TUNE_MULT_HS << 30);
 914                 } else {                /* PIPE_INTERRUPT */
 915                         info1 |= max_packet (maxp) << 16;
 916                         info2 |= hb_mult (maxp) << 30;
 917                 }
 918                 break;
 919         default:
 920                 dbg ("bogus dev %p speed %d", urb->dev, urb->dev->speed);
 921 done:
 922                 qh_put (qh);
 923                 return NULL;
 924         }
 925
 926         /* NOTE:  if (PIPE_INTERRUPT) { scheduler sets s-mask } */
 927
 928         /* init as live, toggle clear, advance to dummy */
 929         qh->qh_state = QH_STATE_IDLE;
 930         hw = qh->hw;
 931         hw->hw_info1 = cpu_to_hc32(ehci, info1);
 932         hw->hw_info2 = cpu_to_hc32(ehci, info2);
 933         usb_settoggle (urb->dev, usb_pipeendpoint (urb->pipe), !is_input, 1);
 934         qh_refresh (ehci, qh);
 935         return qh;
 936 }
 937
 938 /*-------------------------------------------------------------------------*/
 939
 940 /* move qh (and its qtds) onto async queue; maybe enable queue.  */
 941
 942 static void qh_link_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 943 {
 944         __hc32          dma = QH_NEXT(ehci, qh->qh_dma);
 945         struct ehci_qh  *head;
 946
 947         /* Don't link a QH if there's a Clear-TT-Buffer pending */
 948         if (unlikely(qh->clearing_tt))
 949                 return;
 950
 951         WARN_ON(qh->qh_state != QH_STATE_IDLE);
 952
 953         /* (re)start the async schedule? */
 954         head = ehci->async;
 955         timer_action_done (ehci, TIMER_ASYNC_OFF);
 956         if (!head->qh_next.qh) {
 957                 u32     cmd = ehci_readl(ehci, &ehci->regs->command);
 958
 959                 if (!(cmd & CMD_ASE)) {
 960                         /* in case a clear of CMD_ASE didn't take yet */
 961                         (void)handshake(ehci, &ehci->regs->status,
 962                                         STS_ASS, 0, 150);
 963                         cmd |= CMD_ASE | CMD_RUN;
 964                         ehci_writel(ehci, cmd, &ehci->regs->command);
 965                         ehci_to_hcd(ehci)->state = HC_STATE_RUNNING;
 966                         /* posted write need not be known to HC yet ... */
 967                 }
 968         }
 969
 970         /* clear halt and/or toggle; and maybe recover from silicon quirk */
 971         qh_refresh(ehci, qh);
 972
 973         /* splice right after start */
 974         qh->qh_next = head->qh_next;
 975         qh->hw->hw_next = head->hw->hw_next;
 976         wmb ();
 977
 978         head->qh_next.qh = qh;
 979         head->hw->hw_next = dma;
 980
 981         qh_get(qh);
 982         qh->xacterrs = 0;
 983         qh->qh_state = QH_STATE_LINKED;
 984         /* qtd completions reported later by interrupt */
 985 }
 986
 987 /*-------------------------------------------------------------------------*/
 988
 989 /*
 990  * For control/bulk/interrupt, return QH with these TDs appended.
 991  * Allocates and initializes the QH if necessary.
 992  * Returns null if it can't allocate a QH it needs to.
 993  * If the QH has TDs (urbs) already, that's great.
 994  */
 995 static struct ehci_qh *qh_append_tds (
 996         struct ehci_hcd         *ehci,
 997         struct urb              *urb,
 998         struct list_head        *qtd_list,
 999         int                     epnum,
1000         void                    **ptr
1001 )
1002 {
1003         struct ehci_qh          *qh = NULL;
1004         __hc32                  qh_addr_mask = cpu_to_hc32(ehci, 0x7f);
1005
1006         qh = (struct ehci_qh *) *ptr;
1007         if (unlikely (qh == NULL)) {
1008                 /* can't sleep here, we have ehci->lock... */
1009                 qh = qh_make (ehci, urb, GFP_ATOMIC);
1010                 *ptr = qh;
1011         }
1012         if (likely (qh != NULL)) {
1013                 struct ehci_qtd *qtd;
1014
1015                 if (unlikely (list_empty (qtd_list)))
1016                         qtd = NULL;
1017                 else
1018                         qtd = list_entry (qtd_list->next, struct ehci_qtd,
1019                                         qtd_list);
1020
1021                 /* control qh may need patching ... */
1022                 if (unlikely (epnum == 0)) {
1023
1024                         /* usb_reset_device() briefly reverts to address 0 */
1025                         if (usb_pipedevice (urb->pipe) == 0)
1026                                 qh->hw->hw_info1 &= ~qh_addr_mask;
1027                 }
1028
1029                 /* just one way to queue requests: swap with the dummy qtd.
1030                  * only hc or qh_refresh() ever modify the overlay.
1031                  */
1032                 if (likely (qtd != NULL)) {
1033                         struct ehci_qtd         *dummy;
1034                         dma_addr_t              dma;
1035                         __hc32                  token;
1036
1037                         /* to avoid racing the HC, use the dummy td instead of
1038                          * the first td of our list (becomes new dummy).  both
1039                          * tds stay deactivated until we're done, when the
1040                          * HC is allowed to fetch the old dummy (4.10.2).
1041                          */
1042                         token = qtd->hw_token;
1043                         qtd->hw_token = HALT_BIT(ehci);
1044                         wmb ();
1045                         dummy = qh->dummy;
1046
1047                         dma = dummy->qtd_dma;
1048                         *dummy = *qtd;
1049                         dummy->qtd_dma = dma;
1050
1051                         list_del (&qtd->qtd_list);
1052                         list_add (&dummy->qtd_list, qtd_list);
1053                         list_splice_tail(qtd_list, &qh->qtd_list);
1054
1055                         ehci_qtd_init(ehci, qtd, qtd->qtd_dma);
1056                         qh->dummy = qtd;
1057
1058                         /* hc must see the new dummy at list end */
1059                         dma = qtd->qtd_dma;
1060                         qtd = list_entry (qh->qtd_list.prev,
1061                                         struct ehci_qtd, qtd_list);
1062                         qtd->hw_next = QTD_NEXT(ehci, dma);
1063
1064                         /* let the hc process these next qtds */
1065                         wmb ();
1066                         dummy->hw_token = token;
1067
1068                         urb->hcpriv = qh_get (qh);
1069                 }
1070         }
1071         return qh;
1072 }
1073
1074 /*-------------------------------------------------------------------------*/
1075
1076 static int
1077 submit_async (
1078         struct ehci_hcd         *ehci,
1079         struct urb              *urb,
1080         struct list_head        *qtd_list,
1081         gfp_t                   mem_flags
1082 ) {
1083         struct ehci_qtd         *qtd;
1084         int                     epnum;
1085         unsigned long           flags;
1086         struct ehci_qh          *qh = NULL;
1087         int                     rc;
1088
1089         qtd = list_entry (qtd_list->next, struct ehci_qtd, qtd_list);
1090         epnum = urb->ep->desc.bEndpointAddress;
1091
1092 #ifdef EHCI_URB_TRACE
1093         ehci_dbg (ehci,
1094                 "%s %s urb %p ep%d%s len %d, qtd %p [qh %p]\n",
1095                 __func__, urb->dev->devpath, urb,
1096                 epnum & 0x0f, (epnum & USB_DIR_IN) ? "in" : "out",
1097                 urb->transfer_buffer_length,
1098                 qtd, urb->ep->hcpriv);
1099 #endif
1100
1101         spin_lock_irqsave (&ehci->lock, flags);
1102         if (unlikely(!test_bit(HCD_FLAG_HW_ACCESSIBLE,
1103                                &ehci_to_hcd(ehci)->flags))) {
1104                 rc = -ESHUTDOWN;
1105                 goto done;
1106         }
1107         rc = usb_hcd_link_urb_to_ep(ehci_to_hcd(ehci), urb);
1108         if (unlikely(rc))
1109                 goto done;
1110
1111         qh = qh_append_tds(ehci, urb, qtd_list, epnum, &urb->ep->hcpriv);
1112         if (unlikely(qh == NULL)) {
1113                 usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
1114                 rc = -ENOMEM;
1115                 goto done;
1116         }
1117
1118         /* Control/bulk operations through TTs don't need scheduling,
1119          * the HC and TT handle it when the TT has a buffer ready.
1120          */
1121         if (likely (qh->qh_state == QH_STATE_IDLE))
1122                 qh_link_async(ehci, qh);
1123  done:
1124         spin_unlock_irqrestore (&ehci->lock, flags);
1125         if (unlikely (qh == NULL))
1126                 qtd_list_free (ehci, urb, qtd_list);
1127         return rc;
1128 }
1129
1130 /*-------------------------------------------------------------------------*/
1131
1132 /* the async qh for the qtds being reclaimed are now unlinked from the HC */
1133
1134 static void end_unlink_async (struct ehci_hcd *ehci)
1135 {
1136         struct ehci_qh          *qh = ehci->reclaim;
1137         struct ehci_qh          *next;
1138
1139         iaa_watchdog_done(ehci);
1140
1141         // qh->hw_next = cpu_to_hc32(qh->qh_dma);
1142         qh->qh_state = QH_STATE_IDLE;
1143         qh->qh_next.qh = NULL;
1144         qh_put (qh);                    // refcount from reclaim
1145
1146         /* other unlink(s) may be pending (in QH_STATE_UNLINK_WAIT) */
1147         next = qh->reclaim;
1148         ehci->reclaim = next;
1149         qh->reclaim = NULL;
1150
1151         qh_completions (ehci, qh);
1152
1153         if (!list_empty (&qh->qtd_list)
1154                         && HC_IS_RUNNING (ehci_to_hcd(ehci)->state))
1155                 qh_link_async (ehci, qh);
1156         else {
1157                 /* it's not free to turn the async schedule on/off; leave it
1158                  * active but idle for a while once it empties.
1159                  */
1160                 if (HC_IS_RUNNING (ehci_to_hcd(ehci)->state)
1161                                 && ehci->async->qh_next.qh == NULL)
1162                         timer_action (ehci, TIMER_ASYNC_OFF);
1163         }
1164         qh_put(qh);                     /* refcount from async list */
1165
1166         if (next) {
1167                 ehci->reclaim = NULL;
1168                 start_unlink_async (ehci, next);
1169         }
1170 }
1171
1172 /* makes sure the async qh will become idle */
1173 /* caller must own ehci->lock */
1174
1175 static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
1176 {
1177         int             cmd = ehci_readl(ehci, &ehci->regs->command);
1178         struct ehci_qh  *prev;
1179
1180 #ifdef DEBUG
1181         assert_spin_locked(&ehci->lock);
1182         if (ehci->reclaim
1183                         || (qh->qh_state != QH_STATE_LINKED
1184                                 && qh->qh_state != QH_STATE_UNLINK_WAIT)
1185                         )
1186                 BUG ();
1187 #endif
1188
1189         /* stop async schedule right now? */
1190         if (unlikely (qh == ehci->async)) {
1191                 /* can't get here without STS_ASS set */
1192                 if (ehci_to_hcd(ehci)->state != HC_STATE_HALT
1193                                 && !ehci->reclaim) {
1194                         /* ... and CMD_IAAD clear */
1195                         ehci_writel(ehci, cmd & ~CMD_ASE,
1196                                     &ehci->regs->command);
1197                         wmb ();
1198                         // handshake later, if we need to
1199                         timer_action_done (ehci, TIMER_ASYNC_OFF);
1200                 }
1201                 return;
1202         }
1203
1204         qh->qh_state = QH_STATE_UNLINK;
1205         ehci->reclaim = qh = qh_get (qh);
1206
1207         prev = ehci->async;
1208         while (prev->qh_next.qh != qh)
1209                 prev = prev->qh_next.qh;
1210
1211         prev->hw->hw_next = qh->hw->hw_next;
1212         prev->qh_next = qh->qh_next;
1213         wmb ();
1214
1215         /* If the controller isn't running, we don't have to wait for it */
1216         if (unlikely(!HC_IS_RUNNING(ehci_to_hcd(ehci)->state))) {
1217                 /* if (unlikely (qh->reclaim != 0))
1218                  *      this will recurse, probably not much
1219                  */
1220                 end_unlink_async (ehci);
1221                 return;
1222         }
1223
1224         cmd |= CMD_IAAD;
1225         ehci_writel(ehci, cmd, &ehci->regs->command);
1226         (void)ehci_readl(ehci, &ehci->regs->command);
1227         iaa_watchdog_start(ehci);
1228 }
1229
1230 /*-------------------------------------------------------------------------*/
1231
1232 static void scan_async (struct ehci_hcd *ehci)
1233 {
1234         struct ehci_qh          *qh;
1235         enum ehci_timer_action  action = TIMER_IO_WATCHDOG;
1236
1237         ehci->stamp = ehci_readl(ehci, &ehci->regs->frame_index);
1238         timer_action_done (ehci, TIMER_ASYNC_SHRINK);
1239 rescan:
1240         qh = ehci->async->qh_next.qh;
1241         if (likely (qh != NULL)) {
1242                 do {
1243                         /* clean any finished work for this qh */
1244                         if (!list_empty (&qh->qtd_list)
1245                                         && qh->stamp != ehci->stamp) {
1246                                 int temp;
1247
1248                                 /* unlinks could happen here; completion
1249                                  * reporting drops the lock.  rescan using
1250                                  * the latest schedule, but don't rescan
1251                                  * qhs we already finished (no looping).
1252                                  */
1253                                 qh = qh_get (qh);
1254                                 qh->stamp = ehci->stamp;
1255                                 temp = qh_completions (ehci, qh);
1256                                 if (qh->needs_rescan)
1257                                         unlink_async(ehci, qh);
1258                                 qh_put (qh);
1259                                 if (temp != 0) {
1260                                         goto rescan;
1261                                 }
1262                         }
1263
1264                         /* unlink idle entries, reducing DMA usage as well
1265                          * as HCD schedule-scanning costs.  delay for any qh
1266                          * we just scanned, there's a not-unusual case that it
1267                          * doesn't stay idle for long.
1268                          * (plus, avoids some kind of re-activation race.)
1269                          */
1270                         if (list_empty(&qh->qtd_list)
1271                                         && qh->qh_state == QH_STATE_LINKED) {
1272                                 if (!ehci->reclaim
1273                                         && ((ehci->stamp - qh->stamp) & 0x1fff)
1274                                                 >= (EHCI_SHRINK_FRAMES * 8))
1275                                         start_unlink_async(ehci, qh);
1276                                 else
1277                                         action = TIMER_ASYNC_SHRINK;
1278                         }
1279
1280                         qh = qh->qh_next.qh;
1281                 } while (qh);
1282         }
1283         if (action == TIMER_ASYNC_SHRINK)
1284                 timer_action (ehci, TIMER_ASYNC_SHRINK);
1285 }