OHCI: work around for nVidia shutdown problem
authorAlan Stern <stern@rowland.harvard.edu>
Fri, 10 Sep 2010 20:37:05 +0000 (16:37 -0400)
committerGreg Kroah-Hartman <gregkh@suse.de>
Fri, 22 Oct 2010 17:21:36 +0000 (10:21 -0700)
commit3df7169e73fc1d71a39cffeacc969f6840cdf52b
tree8d8eb044f3c3cc723b0a08563311317b8ccea0bf
parent637ed74ff9e86d8c2979e430309a1fd28c921de9
OHCI: work around for nVidia shutdown problem

This patch (as1417) fixes a problem affecting some (or all) nVidia
chipsets.  When the computer is shut down, the OHCI controllers
continue to power the USB buses and evidently they drive a Reset
signal out all their ports.  This prevents attached devices from going
to low power.  Mouse LEDs stay on, for example, which is disconcerting
for users and a drain on laptop batteries.

The fix involves leaving each OHCI controller in the OPERATIONAL state
during system shutdown rather than putting it in the RESET state.
Although this nominally means the controller is running, in fact it's
not doing very much since all the schedules are all disabled.  However
there is ongoing DMA to the Host Controller Communications Area, so
the patch also disables the bus-master capability of all PCI USB
controllers after the shutdown routine runs.

The fix is applied only to nVidia-based PCI OHCI controllers, so it
shouldn't cause problems on systems using other hardware.  As an added
safety measure, in case the kernel encounters one of these running
controllers during boot, the patch changes quirk_usb_handoff_ohci()
(which runs early on during PCI discovery) to reset the controller
before anything bad can happen.

Reported-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: David Brownell <david-b@pacbell.net>
Tested-by: Pali Rohár <pali.rohar@gmail.com>
CC: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
drivers/usb/core/hcd-pci.c
drivers/usb/host/ohci-hcd.c
drivers/usb/host/ohci-pci.c
drivers/usb/host/ohci.h
drivers/usb/host/pci-quirks.c