2 * Copyright (C) 2001-2004 by David Brownell
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.
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
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.
19 /* this file is part of ehci-hcd.c */
21 /*-------------------------------------------------------------------------*/
24 * EHCI Root Hub ... the nonsharable stuff
26 * Registers don't need cpu_to_le32, that happens transparently
29 /*-------------------------------------------------------------------------*/
31 #ifdef CONFIG_USB_PERSIST
33 static int ehci_hub_control(
42 /* After a power loss, ports that were owned by the companion must be
43 * reset so that the companion can still own them.
45 static void ehci_handover_companion_ports(struct ehci_hcd *ehci)
51 struct usb_hcd *hcd = ehci_to_hcd(ehci);
53 if (!ehci->owned_ports)
56 /* Give the connections some time to appear */
59 port = HCS_N_PORTS(ehci->hcs_params);
61 if (test_bit(port, &ehci->owned_ports)) {
62 reg = &ehci->regs->port_status[port];
63 status = ehci_readl(ehci, reg) & ~PORT_RWC_BITS;
65 /* Port already owned by companion? */
66 if (status & PORT_OWNER)
67 clear_bit(port, &ehci->owned_ports);
68 else if (test_bit(port, &ehci->companion_ports))
69 ehci_writel(ehci, status & ~PORT_PE, reg);
71 ehci_hub_control(hcd, SetPortFeature,
72 USB_PORT_FEAT_RESET, port + 1,
77 if (!ehci->owned_ports)
79 msleep(90); /* Wait for resets to complete */
81 port = HCS_N_PORTS(ehci->hcs_params);
83 if (test_bit(port, &ehci->owned_ports)) {
84 ehci_hub_control(hcd, GetPortStatus,
86 (char *) &buf, sizeof(buf));
88 /* The companion should now own the port,
89 * but if something went wrong the port must not
92 reg = &ehci->regs->port_status[port];
93 status = ehci_readl(ehci, reg) & ~PORT_RWC_BITS;
94 if (status & PORT_OWNER)
95 ehci_writel(ehci, status | PORT_CSC, reg);
97 ehci_dbg(ehci, "failed handover port %d: %x\n",
99 ehci_writel(ehci, status & ~PORT_PE, reg);
104 ehci->owned_ports = 0;
107 #else /* CONFIG_USB_PERSIST */
109 static inline void ehci_handover_companion_ports(struct ehci_hcd *ehci)
116 static int ehci_bus_suspend (struct usb_hcd *hcd)
118 struct ehci_hcd *ehci = hcd_to_ehci (hcd);
122 ehci_dbg(ehci, "suspend root hub\n");
124 if (time_before (jiffies, ehci->next_statechange))
127 port = HCS_N_PORTS (ehci->hcs_params);
128 spin_lock_irq (&ehci->lock);
130 /* stop schedules, clean any completed work */
131 if (HC_IS_RUNNING(hcd->state)) {
133 hcd->state = HC_STATE_QUIESCING;
135 ehci->command = ehci_readl(ehci, &ehci->regs->command);
137 ehci->reclaim_ready = 1;
140 /* Unlike other USB host controller types, EHCI doesn't have
141 * any notion of "global" or bus-wide suspend. The driver has
142 * to manually suspend all the active unsuspended ports, and
143 * then manually resume them in the bus_resume() routine.
145 ehci->bus_suspended = 0;
146 ehci->owned_ports = 0;
148 u32 __iomem *reg = &ehci->regs->port_status [port];
149 u32 t1 = ehci_readl(ehci, reg) & ~PORT_RWC_BITS;
152 /* keep track of which ports we suspend */
154 set_bit(port, &ehci->owned_ports);
155 else if ((t1 & PORT_PE) && !(t1 & PORT_SUSPEND)) {
157 set_bit(port, &ehci->bus_suspended);
160 /* enable remote wakeup on all ports */
161 if (device_may_wakeup(&hcd->self.root_hub->dev))
162 t2 |= PORT_WKOC_E|PORT_WKDISC_E|PORT_WKCONN_E;
164 t2 &= ~(PORT_WKOC_E|PORT_WKDISC_E|PORT_WKCONN_E);
167 ehci_vdbg (ehci, "port %d, %08x -> %08x\n",
169 ehci_writel(ehci, t2, reg);
173 /* turn off now-idle HC */
174 del_timer_sync (&ehci->watchdog);
176 hcd->state = HC_STATE_SUSPENDED;
178 /* allow remote wakeup */
180 if (!device_may_wakeup(&hcd->self.root_hub->dev))
182 ehci_writel(ehci, mask, &ehci->regs->intr_enable);
183 ehci_readl(ehci, &ehci->regs->intr_enable);
185 ehci->next_statechange = jiffies + msecs_to_jiffies(10);
186 spin_unlock_irq (&ehci->lock);
191 /* caller has locked the root hub, and should reset/reinit on error */
192 static int ehci_bus_resume (struct usb_hcd *hcd)
194 struct ehci_hcd *ehci = hcd_to_ehci (hcd);
199 if (time_before (jiffies, ehci->next_statechange))
201 spin_lock_irq (&ehci->lock);
203 /* Ideally and we've got a real resume here, and no port's power
204 * was lost. (For PCI, that means Vaux was maintained.) But we
205 * could instead be restoring a swsusp snapshot -- so that BIOS was
206 * the last user of the controller, not reset/pm hardware keeping
207 * state we gave to it.
209 power_okay = ehci_readl(ehci, &ehci->regs->intr_enable);
210 ehci_dbg(ehci, "resume root hub%s\n",
211 power_okay ? "" : " after power loss");
213 /* at least some APM implementations will try to deliver
214 * IRQs right away, so delay them until we're ready.
216 ehci_writel(ehci, 0, &ehci->regs->intr_enable);
218 /* re-init operational registers */
219 ehci_writel(ehci, 0, &ehci->regs->segment);
220 ehci_writel(ehci, ehci->periodic_dma, &ehci->regs->frame_list);
221 ehci_writel(ehci, (u32) ehci->async->qh_dma, &ehci->regs->async_next);
223 /* restore CMD_RUN, framelist size, and irq threshold */
224 ehci_writel(ehci, ehci->command, &ehci->regs->command);
226 /* Some controller/firmware combinations need a delay during which
227 * they set up the port statuses. See Bugzilla #8190. */
230 /* manually resume the ports we suspended during bus_suspend() */
231 i = HCS_N_PORTS (ehci->hcs_params);
233 temp = ehci_readl(ehci, &ehci->regs->port_status [i]);
234 temp &= ~(PORT_RWC_BITS
235 | PORT_WKOC_E | PORT_WKDISC_E | PORT_WKCONN_E);
236 if (test_bit(i, &ehci->bus_suspended) &&
237 (temp & PORT_SUSPEND)) {
238 ehci->reset_done [i] = jiffies + msecs_to_jiffies (20);
241 ehci_writel(ehci, temp, &ehci->regs->port_status [i]);
243 i = HCS_N_PORTS (ehci->hcs_params);
246 temp = ehci_readl(ehci, &ehci->regs->port_status [i]);
247 if (test_bit(i, &ehci->bus_suspended) &&
248 (temp & PORT_SUSPEND)) {
249 temp &= ~(PORT_RWC_BITS | PORT_RESUME);
250 ehci_writel(ehci, temp, &ehci->regs->port_status [i]);
251 ehci_vdbg (ehci, "resumed port %d\n", i + 1);
254 (void) ehci_readl(ehci, &ehci->regs->command);
256 /* maybe re-activate the schedule(s) */
258 if (ehci->async->qh_next.qh)
260 if (ehci->periodic_sched)
263 ehci->command |= temp;
264 ehci_writel(ehci, ehci->command, &ehci->regs->command);
267 ehci->next_statechange = jiffies + msecs_to_jiffies(5);
268 hcd->state = HC_STATE_RUNNING;
270 /* Now we can safely re-enable irqs */
271 ehci_writel(ehci, INTR_MASK, &ehci->regs->intr_enable);
273 spin_unlock_irq (&ehci->lock);
276 ehci_handover_companion_ports(ehci);
282 #define ehci_bus_suspend NULL
283 #define ehci_bus_resume NULL
285 #endif /* CONFIG_PM */
287 /*-------------------------------------------------------------------------*/
289 /* Display the ports dedicated to the companion controller */
290 static ssize_t show_companion(struct class_device *class_dev, char *buf)
292 struct ehci_hcd *ehci;
293 int nports, index, n;
294 int count = PAGE_SIZE;
297 ehci = hcd_to_ehci(bus_to_hcd(class_get_devdata(class_dev)));
298 nports = HCS_N_PORTS(ehci->hcs_params);
300 for (index = 0; index < nports; ++index) {
301 if (test_bit(index, &ehci->companion_ports)) {
302 n = scnprintf(ptr, count, "%d\n", index + 1);
311 * Dedicate or undedicate a port to the companion controller.
312 * Syntax is "[-]portnum", where a leading '-' sign means
313 * return control of the port to the EHCI controller.
315 static ssize_t store_companion(struct class_device *class_dev,
316 const char *buf, size_t count)
318 struct ehci_hcd *ehci;
319 int portnum, new_owner, try;
320 u32 __iomem *status_reg;
323 ehci = hcd_to_ehci(bus_to_hcd(class_get_devdata(class_dev)));
324 new_owner = PORT_OWNER; /* Owned by companion */
325 if (sscanf(buf, "%d", &portnum) != 1)
329 new_owner = 0; /* Owned by EHCI */
331 if (portnum <= 0 || portnum > HCS_N_PORTS(ehci->hcs_params))
333 status_reg = &ehci->regs->port_status[--portnum];
335 set_bit(portnum, &ehci->companion_ports);
337 clear_bit(portnum, &ehci->companion_ports);
340 * The controller won't set the OWNER bit if the port is
341 * enabled, so this loop will sometimes require at least two
342 * iterations: one to disable the port and one to set OWNER.
345 for (try = 4; try > 0; --try) {
346 spin_lock_irq(&ehci->lock);
347 port_status = ehci_readl(ehci, status_reg);
348 if ((port_status & PORT_OWNER) == new_owner
349 || (port_status & (PORT_OWNER | PORT_CONNECT))
353 port_status ^= PORT_OWNER;
354 port_status &= ~(PORT_PE | PORT_RWC_BITS);
355 ehci_writel(ehci, port_status, status_reg);
357 spin_unlock_irq(&ehci->lock);
363 static CLASS_DEVICE_ATTR(companion, 0644, show_companion, store_companion);
365 static inline void create_companion_file(struct ehci_hcd *ehci)
369 /* with integrated TT there is no companion! */
370 if (!ehci_is_TDI(ehci))
371 i = class_device_create_file(ehci_to_hcd(ehci)->self.class_dev,
372 &class_device_attr_companion);
375 static inline void remove_companion_file(struct ehci_hcd *ehci)
377 /* with integrated TT there is no companion! */
378 if (!ehci_is_TDI(ehci))
379 class_device_remove_file(ehci_to_hcd(ehci)->self.class_dev,
380 &class_device_attr_companion);
384 /*-------------------------------------------------------------------------*/
386 static int check_reset_complete (
387 struct ehci_hcd *ehci,
389 u32 __iomem *status_reg,
392 if (!(port_status & PORT_CONNECT)) {
393 ehci->reset_done [index] = 0;
397 /* if reset finished and it's still not enabled -- handoff */
398 if (!(port_status & PORT_PE)) {
400 /* with integrated TT, there's nobody to hand it to! */
401 if (ehci_is_TDI(ehci)) {
403 "Failed to enable port %d on root hub TT\n",
408 ehci_dbg (ehci, "port %d full speed --> companion\n",
411 // what happens if HCS_N_CC(params) == 0 ?
412 port_status |= PORT_OWNER;
413 port_status &= ~PORT_RWC_BITS;
414 ehci_writel(ehci, port_status, status_reg);
417 ehci_dbg (ehci, "port %d high speed\n", index + 1);
422 /*-------------------------------------------------------------------------*/
425 /* build "status change" packet (one or two bytes) from HC registers */
428 ehci_hub_status_data (struct usb_hcd *hcd, char *buf)
430 struct ehci_hcd *ehci = hcd_to_ehci (hcd);
431 u32 temp, status = 0;
433 int ports, i, retval = 1;
436 /* if !USB_SUSPEND, root hub timers won't get shut down ... */
437 if (!HC_IS_RUNNING(hcd->state))
440 /* init status to no-changes */
442 ports = HCS_N_PORTS (ehci->hcs_params);
448 /* Some boards (mostly VIA?) report bogus overcurrent indications,
449 * causing massive log spam unless we completely ignore them. It
450 * may be relevant that VIA VT8235 controlers, where PORT_POWER is
451 * always set, seem to clear PORT_OCC and PORT_CSC when writing to
452 * PORT_POWER; that's surprising, but maybe within-spec.
455 mask = PORT_CSC | PORT_PEC | PORT_OCC;
457 mask = PORT_CSC | PORT_PEC;
458 // PORT_RESUME from hardware ~= PORT_STAT_C_SUSPEND
460 /* no hub change reports (bit 0) for now (power, ...) */
462 /* port N changes (bit N)? */
463 spin_lock_irqsave (&ehci->lock, flags);
464 for (i = 0; i < ports; i++) {
465 temp = ehci_readl(ehci, &ehci->regs->port_status [i]);
468 * Return status information even for ports with OWNER set.
469 * Otherwise khubd wouldn't see the disconnect event when a
470 * high-speed device is switched over to the companion
471 * controller by the user.
474 if (!(temp & PORT_CONNECT))
475 ehci->reset_done [i] = 0;
476 if ((temp & mask) != 0
477 || ((temp & PORT_RESUME) != 0
478 && time_after_eq(jiffies,
479 ehci->reset_done[i]))) {
481 buf [0] |= 1 << (i + 1);
483 buf [1] |= 1 << (i - 7);
487 /* FIXME autosuspend idle root hubs */
488 spin_unlock_irqrestore (&ehci->lock, flags);
489 return status ? retval : 0;
492 /*-------------------------------------------------------------------------*/
495 ehci_hub_descriptor (
496 struct ehci_hcd *ehci,
497 struct usb_hub_descriptor *desc
499 int ports = HCS_N_PORTS (ehci->hcs_params);
502 desc->bDescriptorType = 0x29;
503 desc->bPwrOn2PwrGood = 10; /* ehci 1.0, 2.3.9 says 20ms max */
504 desc->bHubContrCurrent = 0;
506 desc->bNbrPorts = ports;
507 temp = 1 + (ports / 8);
508 desc->bDescLength = 7 + 2 * temp;
510 /* two bitmaps: ports removable, and usb 1.0 legacy PortPwrCtrlMask */
511 memset (&desc->bitmap [0], 0, temp);
512 memset (&desc->bitmap [temp], 0xff, temp);
514 temp = 0x0008; /* per-port overcurrent reporting */
515 if (HCS_PPC (ehci->hcs_params))
516 temp |= 0x0001; /* per-port power control */
518 temp |= 0x0002; /* no power switching */
520 // re-enable when we support USB_PORT_FEAT_INDICATOR below.
521 if (HCS_INDICATOR (ehci->hcs_params))
522 temp |= 0x0080; /* per-port indicators (LEDs) */
524 desc->wHubCharacteristics = (__force __u16)cpu_to_le16 (temp);
527 /*-------------------------------------------------------------------------*/
529 #define PORT_WAKE_BITS (PORT_WKOC_E|PORT_WKDISC_E|PORT_WKCONN_E)
531 static int ehci_hub_control (
539 struct ehci_hcd *ehci = hcd_to_ehci (hcd);
540 int ports = HCS_N_PORTS (ehci->hcs_params);
541 u32 __iomem *status_reg = &ehci->regs->port_status[
542 (wIndex & 0xff) - 1];
549 * FIXME: support SetPortFeatures USB_PORT_FEAT_INDICATOR.
550 * HCS_INDICATOR may say we can change LEDs to off/amber/green.
551 * (track current state ourselves) ... blink for diagnostics,
552 * power, "this is the one", etc. EHCI spec supports this.
555 spin_lock_irqsave (&ehci->lock, flags);
557 case ClearHubFeature:
559 case C_HUB_LOCAL_POWER:
560 case C_HUB_OVER_CURRENT:
561 /* no hub-wide feature/status flags */
567 case ClearPortFeature:
568 if (!wIndex || wIndex > ports)
571 temp = ehci_readl(ehci, status_reg);
574 * Even if OWNER is set, so the port is owned by the
575 * companion controller, khubd needs to be able to clear
576 * the port-change status bits (especially
577 * USB_PORT_FEAT_C_CONNECTION).
581 case USB_PORT_FEAT_ENABLE:
582 ehci_writel(ehci, temp & ~PORT_PE, status_reg);
584 case USB_PORT_FEAT_C_ENABLE:
585 ehci_writel(ehci, (temp & ~PORT_RWC_BITS) | PORT_PEC,
588 case USB_PORT_FEAT_SUSPEND:
589 if (temp & PORT_RESET)
591 if (ehci->no_selective_suspend)
593 if (temp & PORT_SUSPEND) {
594 if ((temp & PORT_PE) == 0)
596 /* resume signaling for 20 msec */
597 temp &= ~(PORT_RWC_BITS | PORT_WAKE_BITS);
598 ehci_writel(ehci, temp | PORT_RESUME,
600 ehci->reset_done [wIndex] = jiffies
601 + msecs_to_jiffies (20);
604 case USB_PORT_FEAT_C_SUSPEND:
605 /* we auto-clear this feature */
607 case USB_PORT_FEAT_POWER:
608 if (HCS_PPC (ehci->hcs_params))
610 temp & ~(PORT_RWC_BITS | PORT_POWER),
613 case USB_PORT_FEAT_C_CONNECTION:
614 ehci_writel(ehci, (temp & ~PORT_RWC_BITS) | PORT_CSC,
617 case USB_PORT_FEAT_C_OVER_CURRENT:
618 ehci_writel(ehci, (temp & ~PORT_RWC_BITS) | PORT_OCC,
621 case USB_PORT_FEAT_C_RESET:
622 /* GetPortStatus clears reset */
627 ehci_readl(ehci, &ehci->regs->command); /* unblock posted write */
629 case GetHubDescriptor:
630 ehci_hub_descriptor (ehci, (struct usb_hub_descriptor *)
634 /* no hub-wide feature/status flags */
636 //cpu_to_le32s ((u32 *) buf);
639 if (!wIndex || wIndex > ports)
643 temp = ehci_readl(ehci, status_reg);
647 status |= 1 << USB_PORT_FEAT_C_CONNECTION;
649 status |= 1 << USB_PORT_FEAT_C_ENABLE;
650 if ((temp & PORT_OCC) && !ignore_oc)
651 status |= 1 << USB_PORT_FEAT_C_OVER_CURRENT;
653 /* whoever resumes must GetPortStatus to complete it!! */
654 if (temp & PORT_RESUME) {
656 /* Remote Wakeup received? */
657 if (!ehci->reset_done[wIndex]) {
658 /* resume signaling for 20 msec */
659 ehci->reset_done[wIndex] = jiffies
660 + msecs_to_jiffies(20);
661 /* check the port again */
662 mod_timer(&ehci_to_hcd(ehci)->rh_timer,
663 ehci->reset_done[wIndex]);
666 /* resume completed? */
667 else if (time_after_eq(jiffies,
668 ehci->reset_done[wIndex])) {
669 status |= 1 << USB_PORT_FEAT_C_SUSPEND;
670 ehci->reset_done[wIndex] = 0;
672 /* stop resume signaling */
673 temp = ehci_readl(ehci, status_reg);
675 temp & ~(PORT_RWC_BITS | PORT_RESUME),
677 retval = handshake(ehci, status_reg,
678 PORT_RESUME, 0, 2000 /* 2msec */);
681 "port %d resume error %d\n",
685 temp &= ~(PORT_SUSPEND|PORT_RESUME|(3<<10));
689 /* whoever resets must GetPortStatus to complete it!! */
690 if ((temp & PORT_RESET)
691 && time_after_eq(jiffies,
692 ehci->reset_done[wIndex])) {
693 status |= 1 << USB_PORT_FEAT_C_RESET;
694 ehci->reset_done [wIndex] = 0;
696 /* force reset to complete */
697 ehci_writel(ehci, temp & ~(PORT_RWC_BITS | PORT_RESET),
699 /* REVISIT: some hardware needs 550+ usec to clear
700 * this bit; seems too long to spin routinely...
702 retval = handshake(ehci, status_reg,
705 ehci_err (ehci, "port %d reset error %d\n",
710 /* see what we found out */
711 temp = check_reset_complete (ehci, wIndex, status_reg,
712 ehci_readl(ehci, status_reg));
715 /* transfer dedicated ports to the companion hc */
716 if ((temp & PORT_CONNECT) &&
717 test_bit(wIndex, &ehci->companion_ports)) {
718 temp &= ~PORT_RWC_BITS;
720 ehci_writel(ehci, temp, status_reg);
721 ehci_dbg(ehci, "port %d --> companion\n", wIndex + 1);
722 temp = ehci_readl(ehci, status_reg);
726 * Even if OWNER is set, there's no harm letting khubd
727 * see the wPortStatus values (they should all be 0 except
728 * for PORT_POWER anyway).
731 if (temp & PORT_CONNECT) {
732 status |= 1 << USB_PORT_FEAT_CONNECTION;
733 // status may be from integrated TT
734 status |= ehci_port_speed(ehci, temp);
737 status |= 1 << USB_PORT_FEAT_ENABLE;
738 if (temp & (PORT_SUSPEND|PORT_RESUME))
739 status |= 1 << USB_PORT_FEAT_SUSPEND;
741 status |= 1 << USB_PORT_FEAT_OVER_CURRENT;
742 if (temp & PORT_RESET)
743 status |= 1 << USB_PORT_FEAT_RESET;
744 if (temp & PORT_POWER)
745 status |= 1 << USB_PORT_FEAT_POWER;
747 #ifndef EHCI_VERBOSE_DEBUG
748 if (status & ~0xffff) /* only if wPortChange is interesting */
750 dbg_port (ehci, "GetStatus", wIndex + 1, temp);
751 put_unaligned(cpu_to_le32 (status), (__le32 *) buf);
755 case C_HUB_LOCAL_POWER:
756 case C_HUB_OVER_CURRENT:
757 /* no hub-wide feature/status flags */
764 selector = wIndex >> 8;
766 if (!wIndex || wIndex > ports)
769 temp = ehci_readl(ehci, status_reg);
770 if (temp & PORT_OWNER)
773 temp &= ~PORT_RWC_BITS;
775 case USB_PORT_FEAT_SUSPEND:
776 if (ehci->no_selective_suspend)
778 if ((temp & PORT_PE) == 0
779 || (temp & PORT_RESET) != 0)
781 if (device_may_wakeup(&hcd->self.root_hub->dev))
782 temp |= PORT_WAKE_BITS;
783 ehci_writel(ehci, temp | PORT_SUSPEND, status_reg);
785 case USB_PORT_FEAT_POWER:
786 if (HCS_PPC (ehci->hcs_params))
787 ehci_writel(ehci, temp | PORT_POWER,
790 case USB_PORT_FEAT_RESET:
791 if (temp & PORT_RESUME)
793 /* line status bits may report this as low speed,
794 * which can be fine if this root hub has a
795 * transaction translator built in.
797 if ((temp & (PORT_PE|PORT_CONNECT)) == PORT_CONNECT
798 && !ehci_is_TDI(ehci)
799 && PORT_USB11 (temp)) {
801 "port %d low speed --> companion\n",
805 ehci_vdbg (ehci, "port %d reset\n", wIndex + 1);
810 * caller must wait, then call GetPortStatus
811 * usb 2.0 spec says 50 ms resets on root
813 ehci->reset_done [wIndex] = jiffies
814 + msecs_to_jiffies (50);
816 ehci_writel(ehci, temp, status_reg);
819 /* For downstream facing ports (these): one hub port is put
820 * into test mode according to USB2 11.24.2.13, then the hub
821 * must be reset (which for root hub now means rmmod+modprobe,
822 * or else system reboot). See EHCI 2.3.9 and 4.14 for info
823 * about the EHCI-specific stuff.
825 case USB_PORT_FEAT_TEST:
826 if (!selector || selector > 5)
830 temp |= selector << 16;
831 ehci_writel(ehci, temp, status_reg);
837 ehci_readl(ehci, &ehci->regs->command); /* unblock posted writes */
842 /* "stall" on error */
845 spin_unlock_irqrestore (&ehci->lock, flags);