On Sun, Dec 29, 2013 at 10:36:56PM +0100, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > The changes in the ACPI-based PCI hotplug (ACPIPHP) subsystem made > during the 3.12 development cycle uncovered a problem with VGA > switcheroo that on some systems, when the device-specific method > (ATPX in the radeon case, _DSM in the nouveau case) is used to turn > off the discrete graphics, the BIOS generates ACPI hotplug events for > that device and those events cause ACPIPHP to attempt to remove the > device from the system (they are events for a device that was present > previously and is not present any more, so that's what should be done > according to the spec). Then, the system stops functioning correctly. > > Since the hotplug events in question were simply silently ignored > previously, the least intrusive way to address that problem is to > make ACPIPHP ignore them again. For this purpose, introduce a new > ACPI device flag, no_hotplug, and modify ACPIPHP to ignore hotplug > events for PCI devices whose ACPI companions have that flag set. > Next, make the radeon and nouveau switcheroo detection code set the > no_hotplug flag for the discrete graphics' ACPI companion. > > Fixes: bbd34fcdd1b2 (ACPI / hotplug / PCI: Register all devices under the given bridge) > References: https://bugzilla.kernel.org/show_bug.cgi?id=61891 > References: https://bugzilla.kernel.org/show_bug.cgi?id=64891 > Reported-and-tested-by: Mike Lothian <mike@xxxxxxxxxxxxxx> > Reported-and-tested-by: <madcatx@xxxxxxxx> > Reported-by: Joaquín Aramendía <samsagax@xxxxxxxxx> > Cc: Alex Deucher <alexdeucher@xxxxxxxxx> > Cc: Dave Airlie <airlied@xxxxxxxx> > Cc: Takashi Iwai <tiwai@xxxxxxx> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > Cc: 3.12+ <stable@xxxxxxxxxxxxxxx> # 3.12+ FWIW, Thunderbolt hotplug still works fine after this patch is applied :) -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
