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
  45static int
  46qtd_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
  87static inline void
  88qh_update (struct ehci_hcd *ehci, struct ehci_qh *qh, struct ehci_qtd *qtd)
  89{
  90	struct ehci_qh_hw *hw = qh->hw;
  91
  92	/* writes to an active overlay are unsafe */
  93	BUG_ON(qh->qh_state != QH_STATE_IDLE);
  94
  95	hw->hw_qtd_next = QTD_NEXT(ehci, qtd->qtd_dma);
  96	hw->hw_alt_next = EHCI_LIST_END(ehci);
  97
  98	/* Except for control endpoints, we make hardware maintain data
  99	 * toggle (like OHCI) ... here (re)initialize the toggle in the QH,
 100	 * and set the pseudo-toggle in udev. Only usb_clear_halt() will
 101	 * ever clear it.
 102	 */
 103	if (!(hw->hw_info1 & cpu_to_hc32(ehci, 1 << 14))) {
 104		unsigned	is_out, epnum;
 105
 106		is_out = qh->is_out;
 107		epnum = (hc32_to_cpup(ehci, &hw->hw_info1) >> 8) & 0x0f;
 108		if (unlikely (!usb_gettoggle (qh->dev, epnum, is_out))) {
 109			hw->hw_token &= ~cpu_to_hc32(ehci, QTD_TOGGLE);
 110			usb_settoggle (qh->dev, epnum, is_out, 1);
 111		}
 112	}
 113
 114	/* 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 */
 123static void
 124qh_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
 144static void qh_link_async(struct ehci_hcd *ehci, struct ehci_qh *qh);
 145
 146static 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
 161static 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
 193static 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
 256static void
 257ehci_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
 299static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh);
 300static void unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh);
 301
 302static 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 */
 309static unsigned
 310qh_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	struct ehci_qh_hw	*hw = qh->hw;
 319
 320	if (unlikely (list_empty (&qh->qtd_list)))
 321		return count;
 322
 323	/* completions (or tasks on other cpus) must never clobber HALT
 324	 * till we've gone through and cleaned everything up, even when
 325	 * they add urbs to this qh's queue or mark them for unlinking.
 326	 *
 327	 * NOTE:  unlinking expects to be done in queue order.
 328	 *
 329	 * It's a bug for qh->qh_state to be anything other than
 330	 * QH_STATE_IDLE, unless our caller is scan_async() or
 331	 * scan_periodic().
 332	 */
 333	state = qh->qh_state;
 334	qh->qh_state = QH_STATE_COMPLETING;
 335	stopped = (state == QH_STATE_IDLE);
 336
 337 rescan:
 338	last = NULL;
 339	last_status = -EINPROGRESS;
 340	qh->needs_rescan = 0;
 341
 342	/* remove de-activated QTDs from front of queue.
 343	 * after faults (including short reads), cleanup this urb
 344	 * then let the queue advance.
 345	 * if queue is stopped, handles unlinks.
 346	 */
 347	list_for_each_safe (entry, tmp, &qh->qtd_list) {
 348		struct ehci_qtd	*qtd;
 349		struct urb	*urb;
 350		u32		token = 0;
 351
 352		qtd = list_entry (entry, struct ehci_qtd, qtd_list);
 353		urb = qtd->urb;
 354
 355		/* clean up any state from previous QTD ...*/
 356		if (last) {
 357			if (likely (last->urb != urb)) {
 358				ehci_urb_done(ehci, last->urb, last_status);
 359				count++;
 360				last_status = -EINPROGRESS;
 361			}
 362			ehci_qtd_free (ehci, last);
 363			last = NULL;
 364		}
 365
 366		/* ignore urbs submitted during completions we reported */
 367		if (qtd == end)
 368			break;
 369
 370		/* hardware copies qtd out of qh overlay */
 371		rmb ();
 372		token = hc32_to_cpu(ehci, qtd->hw_token);
 373
 374		/* always clean up qtds the hc de-activated */
 375 retry_xacterr:
 376		if ((token & QTD_STS_ACTIVE) == 0) {
 377
 
 
 
 
 
 
 
 
 
 
 
 378			/* on STALL, error, and short reads this urb must
 379			 * complete and all its qtds must be recycled.
 380			 */
 381			if ((token & QTD_STS_HALT) != 0) {
 382
 383				/* retry transaction errors until we
 384				 * reach the software xacterr limit
 385				 */
 386				if ((token & QTD_STS_XACT) &&
 387						QTD_CERR(token) == 0 &&
 388						++qh->xacterrs < QH_XACTERR_MAX &&
 389						!urb->unlinked) {
 390					ehci_dbg(ehci,
 391	"detected XactErr len %zu/%zu retry %d\n",
 392	qtd->length - QTD_LENGTH(token), qtd->length, qh->xacterrs);
 393
 394					/* reset the token in the qtd and the
 395					 * qh overlay (which still contains
 396					 * the qtd) so that we pick up from
 397					 * where we left off
 398					 */
 399					token &= ~QTD_STS_HALT;
 400					token |= QTD_STS_ACTIVE |
 401							(EHCI_TUNE_CERR << 10);
 402					qtd->hw_token = cpu_to_hc32(ehci,
 403							token);
 404					wmb();
 405					hw->hw_token = cpu_to_hc32(ehci,
 406							token);
 407					goto retry_xacterr;
 408				}
 409				stopped = 1;
 410
 411			/* magic dummy for some short reads; qh won't advance.
 412			 * that silicon quirk can kick in with this dummy too.
 413			 *
 414			 * other short reads won't stop the queue, including
 415			 * control transfers (status stage handles that) or
 416			 * most other single-qtd reads ... the queue stops if
 417			 * URB_SHORT_NOT_OK was set so the driver submitting
 418			 * the urbs could clean it up.
 419			 */
 420			} else if (IS_SHORT_READ (token)
 421					&& !(qtd->hw_alt_next
 422						& EHCI_LIST_END(ehci))) {
 423				stopped = 1;
 424			}
 425
 426		/* stop scanning when we reach qtds the hc is using */
 427		} else if (likely (!stopped
 428				&& HC_IS_RUNNING (ehci_to_hcd(ehci)->state))) {
 429			break;
 430
 431		/* scan the whole queue for unlinks whenever it stops */
 432		} else {
 433			stopped = 1;
 434
 435			/* cancel everything if we halt, suspend, etc */
 436			if (!HC_IS_RUNNING(ehci_to_hcd(ehci)->state))
 437				last_status = -ESHUTDOWN;
 438
 439			/* this qtd is active; skip it unless a previous qtd
 440			 * for its urb faulted, or its urb was canceled.
 441			 */
 442			else if (last_status == -EINPROGRESS && !urb->unlinked)
 443				continue;
 444
 445			/* qh unlinked; token in overlay may be most current */
 446			if (state == QH_STATE_IDLE
 447					&& cpu_to_hc32(ehci, qtd->qtd_dma)
 448						== hw->hw_current) {
 449				token = hc32_to_cpu(ehci, hw->hw_token);
 450
 451				/* An unlink may leave an incomplete
 452				 * async transaction in the TT buffer.
 453				 * We have to clear it.
 454				 */
 455				ehci_clear_tt_buffer(ehci, qh, urb, token);
 456			}
 457		}
 458
 459		/* unless we already know the urb's status, collect qtd status
 460		 * and update count of bytes transferred.  in common short read
 461		 * cases with only one data qtd (including control transfers),
 462		 * queue processing won't halt.  but with two or more qtds (for
 463		 * example, with a 32 KB transfer), when the first qtd gets a
 464		 * short read the second must be removed by hand.
 465		 */
 466		if (last_status == -EINPROGRESS) {
 467			last_status = qtd_copy_status(ehci, urb,
 468					qtd->length, token);
 469			if (last_status == -EREMOTEIO
 470					&& (qtd->hw_alt_next
 471						& EHCI_LIST_END(ehci)))
 472				last_status = -EINPROGRESS;
 473
 474			/* As part of low/full-speed endpoint-halt processing
 475			 * we must clear the TT buffer (11.17.5).
 476			 */
 477			if (unlikely(last_status != -EINPROGRESS &&
 478					last_status != -EREMOTEIO)) {
 479				/* The TT's in some hubs malfunction when they
 480				 * receive this request following a STALL (they
 481				 * stop sending isochronous packets).  Since a
 482				 * STALL can't leave the TT buffer in a busy
 483				 * state (if you believe Figures 11-48 - 11-51
 484				 * in the USB 2.0 spec), we won't clear the TT
 485				 * buffer in this case.  Strictly speaking this
 486				 * is a violation of the spec.
 487				 */
 488				if (last_status != -EPIPE)
 489					ehci_clear_tt_buffer(ehci, qh, urb,
 490							token);
 491			}
 492		}
 493
 494		/* if we're removing something not at the queue head,
 495		 * patch the hardware queue pointer.
 496		 */
 497		if (stopped && qtd->qtd_list.prev != &qh->qtd_list) {
 498			last = list_entry (qtd->qtd_list.prev,
 499					struct ehci_qtd, qtd_list);
 500			last->hw_next = qtd->hw_next;
 501		}
 502
 503		/* remove qtd; it's recycled after possible urb completion */
 504		list_del (&qtd->qtd_list);
 505		last = qtd;
 506
 507		/* reinit the xacterr counter for the next qtd */
 508		qh->xacterrs = 0;
 509	}
 510
 511	/* last urb's completion might still need calling */
 512	if (likely (last != NULL)) {
 513		ehci_urb_done(ehci, last->urb, last_status);
 514		count++;
 515		ehci_qtd_free (ehci, last);
 516	}
 517
 518	/* Do we need to rescan for URBs dequeued during a giveback? */
 519	if (unlikely(qh->needs_rescan)) {
 520		/* If the QH is already unlinked, do the rescan now. */
 521		if (state == QH_STATE_IDLE)
 522			goto rescan;
 523
 524		/* Otherwise we have to wait until the QH is fully unlinked.
 525		 * Our caller will start an unlink if qh->needs_rescan is
 526		 * set.  But if an unlink has already started, nothing needs
 527		 * to be done.
 528		 */
 529		if (state != QH_STATE_LINKED)
 530			qh->needs_rescan = 0;
 531	}
 532
 533	/* restore original state; caller must unlink or relink */
 534	qh->qh_state = state;
 535
 536	/* be sure the hardware's done with the qh before refreshing
 537	 * it after fault cleanup, or recovering from silicon wrongly
 538	 * overlaying the dummy qtd (which reduces DMA chatter).
 539	 */
 540	if (stopped != 0 || hw->hw_qtd_next == EHCI_LIST_END(ehci)) {
 541		switch (state) {
 542		case QH_STATE_IDLE:
 543			qh_refresh(ehci, qh);
 544			break;
 545		case QH_STATE_LINKED:
 546			/* We won't refresh a QH that's linked (after the HC
 547			 * stopped the queue).  That avoids a race:
 548			 *  - HC reads first part of QH;
 549			 *  - CPU updates that first part and the token;
 550			 *  - HC reads rest of that QH, including token
 551			 * Result:  HC gets an inconsistent image, and then
 552			 * DMAs to/from the wrong memory (corrupting it).
 553			 *
 554			 * That should be rare for interrupt transfers,
 555			 * except maybe high bandwidth ...
 556			 */
 557
 558			/* Tell the caller to start an unlink */
 559			qh->needs_rescan = 1;
 560			break;
 561		/* otherwise, unlink already started */
 562		}
 563	}
 564
 565	return count;
 566}
 567
 568/*-------------------------------------------------------------------------*/
 569
 570// high bandwidth multiplier, as encoded in highspeed endpoint descriptors
 571#define hb_mult(wMaxPacketSize) (1 + (((wMaxPacketSize) >> 11) & 0x03))
 572// ... and packet size, for any kind of endpoint descriptor
 573#define max_packet(wMaxPacketSize) ((wMaxPacketSize) & 0x07ff)
 574
 575/*
 576 * reverse of qh_urb_transaction:  free a list of TDs.
 577 * used for cleanup after errors, before HC sees an URB's TDs.
 578 */
 579static void qtd_list_free (
 580	struct ehci_hcd		*ehci,
 581	struct urb		*urb,
 582	struct list_head	*qtd_list
 583) {
 584	struct list_head	*entry, *temp;
 585
 586	list_for_each_safe (entry, temp, qtd_list) {
 587		struct ehci_qtd	*qtd;
 588
 589		qtd = list_entry (entry, struct ehci_qtd, qtd_list);
 590		list_del (&qtd->qtd_list);
 591		ehci_qtd_free (ehci, qtd);
 592	}
 593}
 594
 595/*
 596 * create a list of filled qtds for this URB; won't link into qh.
 597 */
 598static struct list_head *
 599qh_urb_transaction (
 600	struct ehci_hcd		*ehci,
 601	struct urb		*urb,
 602	struct list_head	*head,
 603	gfp_t			flags
 604) {
 605	struct ehci_qtd		*qtd, *qtd_prev;
 606	dma_addr_t		buf;
 607	int			len, this_sg_len, maxpacket;
 608	int			is_input;
 609	u32			token;
 610	int			i;
 611	struct scatterlist	*sg;
 612
 613	/*
 614	 * URBs map to sequences of QTDs:  one logical transaction
 615	 */
 616	qtd = ehci_qtd_alloc (ehci, flags);
 617	if (unlikely (!qtd))
 618		return NULL;
 619	list_add_tail (&qtd->qtd_list, head);
 620	qtd->urb = urb;
 621
 622	token = QTD_STS_ACTIVE;
 623	token |= (EHCI_TUNE_CERR << 10);
 624	/* for split transactions, SplitXState initialized to zero */
 625
 626	len = urb->transfer_buffer_length;
 627	is_input = usb_pipein (urb->pipe);
 628	if (usb_pipecontrol (urb->pipe)) {
 629		/* SETUP pid */
 630		qtd_fill(ehci, qtd, urb->setup_dma,
 631				sizeof (struct usb_ctrlrequest),
 632				token | (2 /* "setup" */ << 8), 8);
 633
 634		/* ... and always at least one more pid */
 635		token ^= QTD_TOGGLE;
 636		qtd_prev = qtd;
 637		qtd = ehci_qtd_alloc (ehci, flags);
 638		if (unlikely (!qtd))
 639			goto cleanup;
 640		qtd->urb = urb;
 641		qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 642		list_add_tail (&qtd->qtd_list, head);
 643
 644		/* for zero length DATA stages, STATUS is always IN */
 645		if (len == 0)
 646			token |= (1 /* "in" */ << 8);
 647	}
 648
 649	/*
 650	 * data transfer stage:  buffer setup
 651	 */
 652	i = urb->num_sgs;
 653	if (len > 0 && i > 0) {
 654		sg = urb->sg;
 655		buf = sg_dma_address(sg);
 656
 657		/* urb->transfer_buffer_length may be smaller than the
 658		 * size of the scatterlist (or vice versa)
 659		 */
 660		this_sg_len = min_t(int, sg_dma_len(sg), len);
 661	} else {
 662		sg = NULL;
 663		buf = urb->transfer_dma;
 664		this_sg_len = len;
 665	}
 666
 667	if (is_input)
 668		token |= (1 /* "in" */ << 8);
 669	/* else it's already initted to "out" pid (0 << 8) */
 670
 671	maxpacket = max_packet(usb_maxpacket(urb->dev, urb->pipe, !is_input));
 672
 673	/*
 674	 * buffer gets wrapped in one or more qtds;
 675	 * last one may be "short" (including zero len)
 676	 * and may serve as a control status ack
 677	 */
 678	for (;;) {
 679		int this_qtd_len;
 680
 681		this_qtd_len = qtd_fill(ehci, qtd, buf, this_sg_len, token,
 682				maxpacket);
 683		this_sg_len -= this_qtd_len;
 684		len -= this_qtd_len;
 685		buf += this_qtd_len;
 686
 687		/*
 688		 * short reads advance to a "magic" dummy instead of the next
 689		 * qtd ... that forces the queue to stop, for manual cleanup.
 690		 * (this will usually be overridden later.)
 691		 */
 692		if (is_input)
 693			qtd->hw_alt_next = ehci->async->hw->hw_alt_next;
 694
 695		/* qh makes control packets use qtd toggle; maybe switch it */
 696		if ((maxpacket & (this_qtd_len + (maxpacket - 1))) == 0)
 697			token ^= QTD_TOGGLE;
 698
 699		if (likely(this_sg_len <= 0)) {
 700			if (--i <= 0 || len <= 0)
 701				break;
 702			sg = sg_next(sg);
 703			buf = sg_dma_address(sg);
 704			this_sg_len = min_t(int, sg_dma_len(sg), len);
 705		}
 706
 707		qtd_prev = qtd;
 708		qtd = ehci_qtd_alloc (ehci, flags);
 709		if (unlikely (!qtd))
 710			goto cleanup;
 711		qtd->urb = urb;
 712		qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 713		list_add_tail (&qtd->qtd_list, head);
 714	}
 715
 716	/*
 717	 * unless the caller requires manual cleanup after short reads,
 718	 * have the alt_next mechanism keep the queue running after the
 719	 * last data qtd (the only one, for control and most other cases).
 720	 */
 721	if (likely ((urb->transfer_flags & URB_SHORT_NOT_OK) == 0
 722				|| usb_pipecontrol (urb->pipe)))
 723		qtd->hw_alt_next = EHCI_LIST_END(ehci);
 724
 725	/*
 726	 * control requests may need a terminating data "status" ack;
 727	 * bulk ones may need a terminating short packet (zero length).
 
 728	 */
 729	if (likely (urb->transfer_buffer_length != 0)) {
 730		int	one_more = 0;
 731
 732		if (usb_pipecontrol (urb->pipe)) {
 733			one_more = 1;
 734			token ^= 0x0100;	/* "in" <--> "out"  */
 735			token |= QTD_TOGGLE;	/* force DATA1 */
 736		} else if (usb_pipebulk (urb->pipe)
 737				&& (urb->transfer_flags & URB_ZERO_PACKET)
 738				&& !(urb->transfer_buffer_length % maxpacket)) {
 739			one_more = 1;
 740		}
 741		if (one_more) {
 742			qtd_prev = qtd;
 743			qtd = ehci_qtd_alloc (ehci, flags);
 744			if (unlikely (!qtd))
 745				goto cleanup;
 746			qtd->urb = urb;
 747			qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 748			list_add_tail (&qtd->qtd_list, head);
 749
 750			/* never any data in such packets */
 751			qtd_fill(ehci, qtd, 0, 0, token, 0);
 752		}
 753	}
 754
 755	/* by default, enable interrupt on urb completion */
 756	if (likely (!(urb->transfer_flags & URB_NO_INTERRUPT)))
 757		qtd->hw_token |= cpu_to_hc32(ehci, QTD_IOC);
 758	return head;
 759
 760cleanup:
 761	qtd_list_free (ehci, urb, head);
 762	return NULL;
 763}
 764
 765/*-------------------------------------------------------------------------*/
 766
 767// Would be best to create all qh's from config descriptors,
 768// when each interface/altsetting is established.  Unlink
 769// any previous qh and cancel its urbs first; endpoints are
 770// implicitly reset then (data toggle too).
 771// That'd mean updating how usbcore talks to HCDs. (2.7?)
 772
 773
 774/*
 775 * Each QH holds a qtd list; a QH is used for everything except iso.
 776 *
 777 * For interrupt urbs, the scheduler must set the microframe scheduling
 778 * mask(s) each time the QH gets scheduled.  For highspeed, that's
 779 * just one microframe in the s-mask.  For split interrupt transactions
 780 * there are additional complications: c-mask, maybe FSTNs.
 781 */
 782static struct ehci_qh *
 783qh_make (
 784	struct ehci_hcd		*ehci,
 785	struct urb		*urb,
 786	gfp_t			flags
 787) {
 788	struct ehci_qh		*qh = ehci_qh_alloc (ehci, flags);
 789	u32			info1 = 0, info2 = 0;
 790	int			is_input, type;
 791	int			maxp = 0;
 792	struct usb_tt		*tt = urb->dev->tt;
 793	struct ehci_qh_hw	*hw;
 794
 795	if (!qh)
 796		return qh;
 797
 798	/*
 799	 * init endpoint/device data for this QH
 800	 */
 801	info1 |= usb_pipeendpoint (urb->pipe) << 8;
 802	info1 |= usb_pipedevice (urb->pipe) << 0;
 803
 804	is_input = usb_pipein (urb->pipe);
 805	type = usb_pipetype (urb->pipe);
 806	maxp = usb_maxpacket (urb->dev, urb->pipe, !is_input);
 807
 808	/* 1024 byte maxpacket is a hardware ceiling.  High bandwidth
 809	 * acts like up to 3KB, but is built from smaller packets.
 810	 */
 811	if (max_packet(maxp) > 1024) {
 812		ehci_dbg(ehci, "bogus qh maxpacket %d\n", max_packet(maxp));
 813		goto done;
 814	}
 815
 816	/* Compute interrupt scheduling parameters just once, and save.
 817	 * - allowing for high bandwidth, how many nsec/uframe are used?
 818	 * - split transactions need a second CSPLIT uframe; same question
 819	 * - splits also need a schedule gap (for full/low speed I/O)
 820	 * - qh has a polling interval
 821	 *
 822	 * For control/bulk requests, the HC or TT handles these.
 823	 */
 824	if (type == PIPE_INTERRUPT) {
 825		qh->usecs = NS_TO_US(usb_calc_bus_time(USB_SPEED_HIGH,
 826				is_input, 0,
 827				hb_mult(maxp) * max_packet(maxp)));
 828		qh->start = NO_FRAME;
 829		qh->stamp = ehci->periodic_stamp;
 830
 831		if (urb->dev->speed == USB_SPEED_HIGH) {
 832			qh->c_usecs = 0;
 833			qh->gap_uf = 0;
 834
 835			qh->period = urb->interval >> 3;
 836			if (qh->period == 0 && urb->interval != 1) {
 837				/* NOTE interval 2 or 4 uframes could work.
 838				 * But interval 1 scheduling is simpler, and
 839				 * includes high bandwidth.
 840				 */
 841				urb->interval = 1;
 842			} else if (qh->period > ehci->periodic_size) {
 843				qh->period = ehci->periodic_size;
 844				urb->interval = qh->period << 3;
 845			}
 846		} else {
 847			int		think_time;
 848
 849			/* gap is f(FS/LS transfer times) */
 850			qh->gap_uf = 1 + usb_calc_bus_time (urb->dev->speed,
 851					is_input, 0, maxp) / (125 * 1000);
 852
 853			/* FIXME this just approximates SPLIT/CSPLIT times */
 854			if (is_input) {		// SPLIT, gap, CSPLIT+DATA
 855				qh->c_usecs = qh->usecs + HS_USECS (0);
 856				qh->usecs = HS_USECS (1);
 857			} else {		// SPLIT+DATA, gap, CSPLIT
 858				qh->usecs += HS_USECS (1);
 859				qh->c_usecs = HS_USECS (0);
 860			}
 861
 862			think_time = tt ? tt->think_time : 0;
 863			qh->tt_usecs = NS_TO_US (think_time +
 864					usb_calc_bus_time (urb->dev->speed,
 865					is_input, 0, max_packet (maxp)));
 866			qh->period = urb->interval;
 867			if (qh->period > ehci->periodic_size) {
 868				qh->period = ehci->periodic_size;
 869				urb->interval = qh->period;
 870			}
 871		}
 872	}
 873
 874	/* support for tt scheduling, and access to toggles */
 875	qh->dev = urb->dev;
 876
 877	/* using TT? */
 878	switch (urb->dev->speed) {
 879	case USB_SPEED_LOW:
 880		info1 |= (1 << 12);	/* EPS "low" */
 881		/* FALL THROUGH */
 882
 883	case USB_SPEED_FULL:
 884		/* EPS 0 means "full" */
 885		if (type != PIPE_INTERRUPT)
 886			info1 |= (EHCI_TUNE_RL_TT << 28);
 887		if (type == PIPE_CONTROL) {
 888			info1 |= (1 << 27);	/* for TT */
 889			info1 |= 1 << 14;	/* toggle from qtd */
 890		}
 891		info1 |= maxp << 16;
 892
 893		info2 |= (EHCI_TUNE_MULT_TT << 30);
 894
 895		/* Some Freescale processors have an erratum in which the
 896		 * port number in the queue head was 0..N-1 instead of 1..N.
 897		 */
 898		if (ehci_has_fsl_portno_bug(ehci))
 899			info2 |= (urb->dev->ttport-1) << 23;
 900		else
 901			info2 |= urb->dev->ttport << 23;
 902
 903		/* set the address of the TT; for TDI's integrated
 904		 * root hub tt, leave it zeroed.
 905		 */
 906		if (tt && tt->hub != ehci_to_hcd(ehci)->self.root_hub)
 907			info2 |= tt->hub->devnum << 16;
 908
 909		/* NOTE:  if (PIPE_INTERRUPT) { scheduler sets c-mask } */
 910
 911		break;
 912
 913	case USB_SPEED_HIGH:		/* no TT involved */
 914		info1 |= (2 << 12);	/* EPS "high" */
 915		if (type == PIPE_CONTROL) {
 916			info1 |= (EHCI_TUNE_RL_HS << 28);
 917			info1 |= 64 << 16;	/* usb2 fixed maxpacket */
 918			info1 |= 1 << 14;	/* toggle from qtd */
 919			info2 |= (EHCI_TUNE_MULT_HS << 30);
 920		} else if (type == PIPE_BULK) {
 921			info1 |= (EHCI_TUNE_RL_HS << 28);
 922			/* The USB spec says that high speed bulk endpoints
 923			 * always use 512 byte maxpacket.  But some device
 924			 * vendors decided to ignore that, and MSFT is happy
 925			 * to help them do so.  So now people expect to use
 926			 * such nonconformant devices with Linux too; sigh.
 927			 */
 928			info1 |= max_packet(maxp) << 16;
 929			info2 |= (EHCI_TUNE_MULT_HS << 30);
 930		} else {		/* PIPE_INTERRUPT */
 931			info1 |= max_packet (maxp) << 16;
 932			info2 |= hb_mult (maxp) << 30;
 933		}
 934		break;
 935	default:
 936		dbg ("bogus dev %p speed %d", urb->dev, urb->dev->speed);
 
 937done:
 938		qh_put (qh);
 939		return NULL;
 940	}
 941
 942	/* NOTE:  if (PIPE_INTERRUPT) { scheduler sets s-mask } */
 943
 944	/* init as live, toggle clear, advance to dummy */
 945	qh->qh_state = QH_STATE_IDLE;
 946	hw = qh->hw;
 947	hw->hw_info1 = cpu_to_hc32(ehci, info1);
 948	hw->hw_info2 = cpu_to_hc32(ehci, info2);
 949	qh->is_out = !is_input;
 950	usb_settoggle (urb->dev, usb_pipeendpoint (urb->pipe), !is_input, 1);
 951	qh_refresh (ehci, qh);
 952	return qh;
 953}
 954
 955/*-------------------------------------------------------------------------*/
 956
 957/* move qh (and its qtds) onto async queue; maybe enable queue.  */
 958
 959static void qh_link_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 960{
 961	__hc32		dma = QH_NEXT(ehci, qh->qh_dma);
 962	struct ehci_qh	*head;
 963
 964	/* Don't link a QH if there's a Clear-TT-Buffer pending */
 965	if (unlikely(qh->clearing_tt))
 966		return;
 967
 968	WARN_ON(qh->qh_state != QH_STATE_IDLE);
 969
 970	/* (re)start the async schedule? */
 971	head = ehci->async;
 972	timer_action_done (ehci, TIMER_ASYNC_OFF);
 973	if (!head->qh_next.qh) {
 974		u32	cmd = ehci_readl(ehci, &ehci->regs->command);
 975
 976		if (!(cmd & CMD_ASE)) {
 977			/* in case a clear of CMD_ASE didn't take yet */
 978			(void)handshake(ehci, &ehci->regs->status,
 979					STS_ASS, 0, 150);
 980			cmd |= CMD_ASE | CMD_RUN;
 981			ehci_writel(ehci, cmd, &ehci->regs->command);
 982			ehci_to_hcd(ehci)->state = HC_STATE_RUNNING;
 983			/* posted write need not be known to HC yet ... */
 984		}
 985	}
 986
 987	/* clear halt and/or toggle; and maybe recover from silicon quirk */
 988	qh_refresh(ehci, qh);
 989
 990	/* splice right after start */
 991	qh->qh_next = head->qh_next;
 992	qh->hw->hw_next = head->hw->hw_next;
 993	wmb ();
 994
 995	head->qh_next.qh = qh;
 996	head->hw->hw_next = dma;
 997
 998	qh_get(qh);
 999	qh->xacterrs = 0;
1000	qh->qh_state = QH_STATE_LINKED;
1001	/* qtd completions reported later by interrupt */
1002}
1003
1004/*-------------------------------------------------------------------------*/
1005
1006/*
1007 * For control/bulk/interrupt, return QH with these TDs appended.
1008 * Allocates and initializes the QH if necessary.
1009 * Returns null if it can't allocate a QH it needs to.
1010 * If the QH has TDs (urbs) already, that's great.
1011 */
1012static struct ehci_qh *qh_append_tds (
1013	struct ehci_hcd		*ehci,
1014	struct urb		*urb,
1015	struct list_head	*qtd_list,
1016	int			epnum,
1017	void			**ptr
1018)
1019{
1020	struct ehci_qh		*qh = NULL;
1021	__hc32			qh_addr_mask = cpu_to_hc32(ehci, 0x7f);
1022
1023	qh = (struct ehci_qh *) *ptr;
1024	if (unlikely (qh == NULL)) {
1025		/* can't sleep here, we have ehci->lock... */
1026		qh = qh_make (ehci, urb, GFP_ATOMIC);
1027		*ptr = qh;
1028	}
1029	if (likely (qh != NULL)) {
1030		struct ehci_qtd	*qtd;
1031
1032		if (unlikely (list_empty (qtd_list)))
1033			qtd = NULL;
1034		else
1035			qtd = list_entry (qtd_list->next, struct ehci_qtd,
1036					qtd_list);
1037
1038		/* control qh may need patching ... */
1039		if (unlikely (epnum == 0)) {
1040
1041                        /* usb_reset_device() briefly reverts to address 0 */
1042                        if (usb_pipedevice (urb->pipe) == 0)
1043				qh->hw->hw_info1 &= ~qh_addr_mask;
1044		}
1045
1046		/* just one way to queue requests: swap with the dummy qtd.
1047		 * only hc or qh_refresh() ever modify the overlay.
1048		 */
1049		if (likely (qtd != NULL)) {
1050			struct ehci_qtd		*dummy;
1051			dma_addr_t		dma;
1052			__hc32			token;
1053
1054			/* to avoid racing the HC, use the dummy td instead of
1055			 * the first td of our list (becomes new dummy).  both
1056			 * tds stay deactivated until we're done, when the
1057			 * HC is allowed to fetch the old dummy (4.10.2).
1058			 */
1059			token = qtd->hw_token;
1060			qtd->hw_token = HALT_BIT(ehci);
1061			wmb ();
1062			dummy = qh->dummy;
1063
1064			dma = dummy->qtd_dma;
1065			*dummy = *qtd;
1066			dummy->qtd_dma = dma;
1067
1068			list_del (&qtd->qtd_list);
1069			list_add (&dummy->qtd_list, qtd_list);
1070			list_splice_tail(qtd_list, &qh->qtd_list);
1071
1072			ehci_qtd_init(ehci, qtd, qtd->qtd_dma);
1073			qh->dummy = qtd;
1074
1075			/* hc must see the new dummy at list end */
1076			dma = qtd->qtd_dma;
1077			qtd = list_entry (qh->qtd_list.prev,
1078					struct ehci_qtd, qtd_list);
1079			qtd->hw_next = QTD_NEXT(ehci, dma);
1080
1081			/* let the hc process these next qtds */
1082			wmb ();
1083			dummy->hw_token = token;
1084
1085			urb->hcpriv = qh_get (qh);
1086		}
1087	}
1088	return qh;
1089}
1090
1091/*-------------------------------------------------------------------------*/
1092
1093static int
1094submit_async (
1095	struct ehci_hcd		*ehci,
1096	struct urb		*urb,
1097	struct list_head	*qtd_list,
1098	gfp_t			mem_flags
1099) {
1100	int			epnum;
1101	unsigned long		flags;
1102	struct ehci_qh		*qh = NULL;
1103	int			rc;
1104
1105	epnum = urb->ep->desc.bEndpointAddress;
1106
1107#ifdef EHCI_URB_TRACE
1108	{
1109		struct ehci_qtd *qtd;
1110		qtd = list_entry(qtd_list->next, struct ehci_qtd, qtd_list);
1111		ehci_dbg(ehci,
1112			 "%s %s urb %p ep%d%s len %d, qtd %p [qh %p]\n",
1113			 __func__, urb->dev->devpath, urb,
1114			 epnum & 0x0f, (epnum & USB_DIR_IN) ? "in" : "out",
1115			 urb->transfer_buffer_length,
1116			 qtd, urb->ep->hcpriv);
1117	}
1118#endif
1119
1120	spin_lock_irqsave (&ehci->lock, flags);
1121	if (unlikely(!HCD_HW_ACCESSIBLE(ehci_to_hcd(ehci)))) {
1122		rc = -ESHUTDOWN;
1123		goto done;
1124	}
1125	rc = usb_hcd_link_urb_to_ep(ehci_to_hcd(ehci), urb);
1126	if (unlikely(rc))
1127		goto done;
1128
1129	qh = qh_append_tds(ehci, urb, qtd_list, epnum, &urb->ep->hcpriv);
1130	if (unlikely(qh == NULL)) {
1131		usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
1132		rc = -ENOMEM;
1133		goto done;
1134	}
1135
1136	/* Control/bulk operations through TTs don't need scheduling,
1137	 * the HC and TT handle it when the TT has a buffer ready.
1138	 */
1139	if (likely (qh->qh_state == QH_STATE_IDLE))
1140		qh_link_async(ehci, qh);
1141 done:
1142	spin_unlock_irqrestore (&ehci->lock, flags);
1143	if (unlikely (qh == NULL))
1144		qtd_list_free (ehci, urb, qtd_list);
1145	return rc;
1146}
1147
1148/*-------------------------------------------------------------------------*/
1149
1150/* the async qh for the qtds being reclaimed are now unlinked from the HC */
1151
1152static void end_unlink_async (struct ehci_hcd *ehci)
1153{
1154	struct ehci_qh		*qh = ehci->reclaim;
1155	struct ehci_qh		*next;
1156
1157	iaa_watchdog_done(ehci);
1158
1159	// qh->hw_next = cpu_to_hc32(qh->qh_dma);
1160	qh->qh_state = QH_STATE_IDLE;
1161	qh->qh_next.qh = NULL;
1162	qh_put (qh);			// refcount from reclaim
1163
1164	/* other unlink(s) may be pending (in QH_STATE_UNLINK_WAIT) */
1165	next = qh->reclaim;
1166	ehci->reclaim = next;
1167	qh->reclaim = NULL;
1168
1169	qh_completions (ehci, qh);
1170
1171	if (!list_empty (&qh->qtd_list)
1172			&& HC_IS_RUNNING (ehci_to_hcd(ehci)->state))
1173		qh_link_async (ehci, qh);
1174	else {
1175		/* it's not free to turn the async schedule on/off; leave it
1176		 * active but idle for a while once it empties.
1177		 */
1178		if (HC_IS_RUNNING (ehci_to_hcd(ehci)->state)
1179				&& ehci->async->qh_next.qh == NULL)
1180			timer_action (ehci, TIMER_ASYNC_OFF);
1181	}
1182	qh_put(qh);			/* refcount from async list */
1183
1184	if (next) {
1185		ehci->reclaim = NULL;
1186		start_unlink_async (ehci, next);
1187	}
1188
1189	if (ehci->has_synopsys_hc_bug)
1190		ehci_writel(ehci, (u32) ehci->async->qh_dma,
1191			    &ehci->regs->async_next);
1192}
1193
1194/* makes sure the async qh will become idle */
1195/* caller must own ehci->lock */
1196
1197static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
1198{
1199	int		cmd = ehci_readl(ehci, &ehci->regs->command);
1200	struct ehci_qh	*prev;
1201
1202#ifdef DEBUG
1203	assert_spin_locked(&ehci->lock);
1204	if (ehci->reclaim
1205			|| (qh->qh_state != QH_STATE_LINKED
1206				&& qh->qh_state != QH_STATE_UNLINK_WAIT)
1207			)
1208		BUG ();
1209#endif
1210
1211	/* stop async schedule right now? */
1212	if (unlikely (qh == ehci->async)) {
1213		/* can't get here without STS_ASS set */
1214		if (ehci_to_hcd(ehci)->state != HC_STATE_HALT
1215				&& !ehci->reclaim) {
1216			/* ... and CMD_IAAD clear */
1217			ehci_writel(ehci, cmd & ~CMD_ASE,
1218				    &ehci->regs->command);
1219			wmb ();
1220			// handshake later, if we need to
1221			timer_action_done (ehci, TIMER_ASYNC_OFF);
1222		}
1223		return;
1224	}
1225
1226	qh->qh_state = QH_STATE_UNLINK;
1227	ehci->reclaim = qh = qh_get (qh);
1228
1229	prev = ehci->async;
1230	while (prev->qh_next.qh != qh)
1231		prev = prev->qh_next.qh;
1232
1233	prev->hw->hw_next = qh->hw->hw_next;
1234	prev->qh_next = qh->qh_next;
1235	if (ehci->qh_scan_next == qh)
1236		ehci->qh_scan_next = qh->qh_next.qh;
1237	wmb ();
1238
1239	/* If the controller isn't running, we don't have to wait for it */
1240	if (unlikely(!HC_IS_RUNNING(ehci_to_hcd(ehci)->state))) {
1241		/* if (unlikely (qh->reclaim != 0))
1242		 *	this will recurse, probably not much
1243		 */
1244		end_unlink_async (ehci);
1245		return;
1246	}
1247
1248	cmd |= CMD_IAAD;
1249	ehci_writel(ehci, cmd, &ehci->regs->command);
1250	(void)ehci_readl(ehci, &ehci->regs->command);
1251	iaa_watchdog_start(ehci);
1252}
1253
1254/*-------------------------------------------------------------------------*/
1255
1256static void scan_async (struct ehci_hcd *ehci)
1257{
1258	bool			stopped;
1259	struct ehci_qh		*qh;
1260	enum ehci_timer_action	action = TIMER_IO_WATCHDOG;
1261
1262	timer_action_done (ehci, TIMER_ASYNC_SHRINK);
1263	stopped = !HC_IS_RUNNING(ehci_to_hcd(ehci)->state);
1264
1265	ehci->qh_scan_next = ehci->async->qh_next.qh;
1266	while (ehci->qh_scan_next) {
1267		qh = ehci->qh_scan_next;
1268		ehci->qh_scan_next = qh->qh_next.qh;
1269 rescan:
1270		/* clean any finished work for this qh */
1271		if (!list_empty(&qh->qtd_list)) {
1272			int temp;
1273
1274			/*
1275			 * Unlinks could happen here; completion reporting
1276			 * drops the lock.  That's why ehci->qh_scan_next
1277			 * always holds the next qh to scan; if the next qh
1278			 * gets unlinked then ehci->qh_scan_next is adjusted
1279			 * in start_unlink_async().
1280			 */
1281			qh = qh_get(qh);
1282			temp = qh_completions(ehci, qh);
1283			if (qh->needs_rescan)
1284				unlink_async(ehci, qh);
1285			qh->unlink_time = jiffies + EHCI_SHRINK_JIFFIES;
1286			qh_put(qh);
1287			if (temp != 0)
1288				goto rescan;
1289		}
1290
1291		/* unlink idle entries, reducing DMA usage as well
1292		 * as HCD schedule-scanning costs.  delay for any qh
1293		 * we just scanned, there's a not-unusual case that it
1294		 * doesn't stay idle for long.
1295		 * (plus, avoids some kind of re-activation race.)
1296		 */
1297		if (list_empty(&qh->qtd_list)
1298				&& qh->qh_state == QH_STATE_LINKED) {
1299			if (!ehci->reclaim && (stopped ||
1300					time_after_eq(jiffies, qh->unlink_time)))
1301				start_unlink_async(ehci, qh);
1302			else
1303				action = TIMER_ASYNC_SHRINK;
1304		}
1305	}
1306	if (action == TIMER_ASYNC_SHRINK)
1307		timer_action (ehci, TIMER_ASYNC_SHRINK);
1308}