xhci: Make handover code more robust
authorMatthew Garrett <mjg@redhat.com>
Tue, 14 Aug 2012 20:44:49 +0000 (16:44 -0400)
committerSarah Sharp <sarah.a.sharp@linux.intel.com>
Wed, 5 Sep 2012 19:07:17 +0000 (12:07 -0700)
commite955a1cd086de4d165ae0f4c7be7289d84b63bdc
tree849f0cf3879214e10ec4eee0b2ae8c00f23322c3
parent052c7f9ffb0e95843e75448d02664459253f9ff8
xhci: Make handover code more robust

My test platform (Intel DX79SI) boots reliably under BIOS, but frequently
crashes when booting via UEFI. I finally tracked this down to the xhci
handoff code. It seems that reads from the device occasionally just return
0xff, resulting in xhci_find_next_cap_offset generating a value that's
larger than the resource region. We then oops when attempting to read the
value. Sanity checking that value lets us avoid the crash.

I've no idea what's causing the underlying problem, and xhci still doesn't
actually *work* even with this, but the machine at least boots which will
probably make further debugging easier.

This should be backported to kernels as old as 2.6.31, that contain the
commit 66d4eadd8d067269ea8fead1a50fe87c2979a80d "USB: xhci: BIOS handoff
and HW initialization."

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org
drivers/usb/host/pci-quirks.c