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xHCI: Increase the timeout for controller save/restore state operation
authorAndiry Xu <andiry.xu@gmail.com>
Wed, 13 Jun 2012 02:51:57 +0000 (10:51 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 22 Jun 2012 18:34:14 +0000 (11:34 -0700)
commit482a7756a282b7873dcba9441504a32354317d49
treea42bc377e56b7132b4246ffba969f72759e76d98
parent1466988e8be36b25f01123798ce430176911c3c5
xHCI: Increase the timeout for controller save/restore state operation

commit 622eb783fe6ff4c1baa47db16c3a5db97f9e6e50 upstream.

When system software decides to power down the xHC with the intent of
resuming operation at a later time, it will ask xHC to save the internal
state and restore it when resume to correctly recover from a power event.
Two bits are used to enable this operation: Save State and Restore State.

xHCI spec 4.23.2 says software should "Set the Controller Save/Restore
State flag in the USBCMD register and wait for the Save/Restore State
Status flag in the USBSTS register to transition to '0'". However, it does
not define how long software should wait for the SSS/RSS bit to transition
to 0.

Currently the timeout is set to 1ms. There is bug report
(https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1002697)
indicates that the timeout is too short for ASMedia ASM1042 host controller
to save/restore the state successfully. Increase the timeout to 10ms helps to
resolve the issue.

This patch should be backported to stable kernels as old as 2.6.37, that
contain the commit 5535b1d5f8885695c6ded783c692e3c0d0eda8ca "USB: xHCI:
PCI power management implementation"

Signed-off-by: Andiry Xu <andiry.xu@gmail.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/usb/host/xhci.c