> -----Original Message----- > From: Lukas Wunner [mailto:lukas@xxxxxxxxx] > Sent: Wednesday, January 04, 2017 3:17 AM > To: Bjorn Helgaas > Cc: Rafael J. Wysocki; Peter Wu; Mika Westerberg; Kilian Singer; linux-pci; > Deucher, Alexander; Dave Airlie > Subject: Re: PCI: Revert "PCI: Add runtime PM support for PCIe ports" > > On Tue, Jan 03, 2017 at 06:05:57PM -0600, Bjorn Helgaas wrote: > > I don't *want* to apply the revert. It's on my for-linus branch as a > > worst-case scenario change if we can't figure out a better fix. > > > > The patch below is preferable, but I'd rather not take even it, > > because it takes away functionality and forces people to use a boot > > parameter to restore it. I expect that somebody will figure out how > > to fix the regression Kilian found and also keep the new functionality > > (without requiring boot parameters) before v4.10. > > The issue is constrained to hybrid graphics laptops with Nvidia discrete > GPU using nouveau. Hence it needs to be fixed in nouveau, not in the > PCI core. > > (AFAIUI, laptops with AMD discrete GPU are not affected as it is known > when and how to call an ACPI method versus using PR3.) > > (Neither are laptops using the Nvidia proprietary driver as it doesn't > runtime suspend the card. But battery life will be terrible then.) > > We're at rc2 so the time frame for coming up with a fix is probably > 4 weeks. Peter and others have tried for months to reverse-engineer > how to handle runtime PM on newer Nvidia cards. It seems likely that > we'll not find the ultimate solution to the problem within 4 weeks. > > The way it is now, i.e. defaulting to PR3 when available, regresses > certain laptops such as Kilian's. If on the other hand we default to > DSM when available, we'll regress certain other laptops, as Peter has > pointed out. Whitelisting or blacklisting laptops doesn't seem a good > approach either, ideally we'd want to use PR3 as Windows does. > > As said, the only short-term solution I see is to add an "optimus" > module_param to nouveau to allow users to select which method to use. > So in Kilian's case an additional command line parameter would be > necessary to fix the issue. > > Does anyone see a better solution or can we agree on this one? If so > I can come up with a patch. This could go in via Dave Airlie's tree. I think an option may be useful for testing, but I think the best solution is probably a quirk for Kilian's system unless there are a lot of users having similar problems to Killian. PR3 standardizes dGPU power control so things should get better across the board. Alex -- 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
