On Monday, December 30, 2013 11:20:43 AM Mika Westerberg wrote: > 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 :) I've checked that, but thanks for the confirmation! Rafael -- 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
