Commit 71c731a2 (usb: host: xhci: Fix Compliance Mode on SN65LVPE502CP
Hardware) was a workaround for systems using the SN65LVPE502CP,
controller, but it introduced a bug in resume from hibernate.
The fix created a timer, comp_mode_recovery_timer, which is deleted from
a timer list when xhci_suspend() is called. However, the hibernate image,
including the timer list containing the comp_mode_recovery_timer, had
already been saved before the timer was deleted.
Upon resume from hibernate, the list containing the comp_mode_recovery_timer
is restored from the image saved to disk, and xhci_resume(), assuming that
the timer had been deleted by xhci_suspend(), makes a call to
compliance_mode_recoery_timer_init(), which creates a new instance of the
comp_mode_recovery_timer and attempts to place it into the same list in which
it is already active, thus corrupting the list during the list_add() call.
At this point, a call trace is emitted indicating the list corruption.
Soon afterward, the system locks up, the watchdog times out, and the
ensuing NMI crashes the system.
The problem did not occur when resuming from suspend. In suspend, the
image in RAM remains exactly as it was when xhci_suspend() deleted the
comp_mode_recovery_timer, so there is no problem when xhci_resume()
creates a new instance of this timer and places it in the still empty
list.
This patch avoids the problem by deleting the timer in xhci_resume()
when resuming from hibernate. Now xhci_resume() can safely make the
call to create a new instance of this timer, whether returning from
suspend or hibernate.
Thanks to Alan Stern for his help with understanding the problem.
Signed-off-by: Tony Camuso <tcamuso@xxxxxxxxxx>
Acked-by: Don Zickus <dzickus@xxxxxxxxxx>
---
drivers/usb/host/xhci.c | 9 ++++++++-
1 files changed, 8 insertions(+), 1 deletions(-)
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index f1f01a8..fe4f7ab 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -988,6 +988,13 @@ int xhci_resume(struct xhci_hcd *xhci, bool hibernated)
/* If restore operation fails, re-initialize the HC during resume */
if ((temp & STS_SRE) || hibernated) {
+
+ if ((xhci->quirks & XHCI_COMP_MODE_QUIRK) &&
+ !(xhci_all_ports_seen_u0(xhci))) {
+ del_timer_sync(&xhci->comp_mode_recovery_timer);
+ xhci_dbg(xhci, "Compliance Mode Recovery Timer deleted!\n");
+ }
+
/* Let the USB core know _both_ roothubs lost power. */
usb_root_hub_lost_power(xhci->main_hcd->self.root_hub);
usb_root_hub_lost_power(xhci->shared_hcd->self.root_hub);
@@ -1071,7 +1078,7 @@ int xhci_resume(struct xhci_hcd *xhci, bool hibernated)
* to suffer the Compliance Mode issue again. It doesn't matter if
* ports have entered previously to U0 before system's suspension.
*/
- if (xhci->quirks & XHCI_COMP_MODE_QUIRK)
+ if ((xhci->quirks & XHCI_COMP_MODE_QUIRK) && !hibernated)
compliance_mode_recovery_timer_init(xhci);
/* Re-enable port polling. */
--
1.7.1
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