On Sat, Jan 07, 2017 at 12:35:10PM +0100, Peter Wu wrote: > On Thu, Jan 05, 2017 at 03:42:20PM +0100, Lukas Wunner wrote: > > On Wed, Jan 04, 2017 at 10:09:54PM +0100, Peter Wu wrote: > > > [ Help/ideas are welcome, I suspect that these failures to restore power > > > on laptops designed for Win8+ all have the same cause, related to some > > > unknown interaction between ACPI and PCI. Some links: > > > https://bugzilla.kernel.org/show_bug.cgi?id=190861 > > > https://bugzilla.kernel.org/show_bug.cgi?id=156341 ] > > > > Looking at Kilian's acpidump again I notice that the methods to power > > the GPU on or off (GPON / GPOF) are called from two places: > > > > - From the _PS0 and _PS3 methods of the GPU and > > - from the _PR3 power resource of the root port above the GPU. > > > > In the former case they're called for pre Windows 2013 or if VDAD is true. > > In the latter case they're called unconditionally but GPOF becomes a no-op > > in the pre Windows 2013 case. > > > > This means that GPOF would be executed *twice* on Windows 2013+ if VDAD > > is true. I could imagine this to cause issues. > > There is a flag "DGOS" which is set when PGON/PGOF are called, so > multiple invocations should not matter for the powerdown/up sequence. > There are some SMI calls though that might have side-effects though. The PGON method becomes a no-op if DGOS is true. But the PGOF method doesn't check DGOS. Thanks, Lukas -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
