On 10 March 2016 at 06:17, Lukas Wunner <lukas at wunner.de> wrote: > Hi, > > On Wed, Mar 09, 2016 at 11:52:33AM -0500, Alex Deucher wrote: >> On Wed, Mar 9, 2016 at 9:33 AM, Lukas Wunner <lukas at wunner.de> wrote: >> > On Wed, Mar 09, 2016 at 04:14:04PM +1000, Dave Airlie wrote: >> >> From: Dave Airlie <airlied at redhat.com> >> >> >> >> Windows 10 seems to have standardised power control for the >> >> optimus/powerxpress laptops using PR3 power resource hooks. >> > >> > What happened to the Optimus DSM, does this still work? If not, >> > echoing OFF to the vgaswitcheroo sysfs file won't power down the >> > GPU now, right? (If runtime pm is disabled in nouveau.) >> > >> If the OS identifies itself as windows 10 or newer when initializing >> ACPI, the standardized interfaces should be used if they exist. I'm >> not sure if there is any explicit policy on the vendor specific ones, >> but I suspect they are probably broken in that case since I doubt the >> OEM validates them when the standardized interfaces are available. > > The vendor interface (Optimus DSM) must be present, otherwise the call > to nouveau_is_optimus() in patch [2/2] would return false. > > But indeed it seems to not be working, otherwise why would the patches > be necessary? > > My point is that the chosen approach does not square with vga_switcheroo's > architecture: Normally it's the handler's job to power the GPU up/down. > If runtime pm is enabled then vga_switcheroo_init_domain_pm_ops() > activates runtime_suspend/_resume callbacks which ask the handler to > flip the power switch. > > However these two patches add *additional* runtime_suspend/_resume > callbacks which do not rely on the handler at all. The handler is thus > useless. This becomes apparent when loading the nouveau module with > runpm=0: Normally the user is then able to manually power the GPU > up/down by echoing ON or OFF to the vgaswitcheroo sysfs file. With the > chosen approach this will likely not work because the handler only knows > how to invoke the DSM, it doesn't know anything about PR3. > > Hence my suggestion to solve this with an additional handler which > gets used in lieu of the nouveau DSM handler.
I'll think about this a bit more, but really I don't care for vgaswitcheroo manual power control anymore. It's in debugfs for a reason, it was a stopgap until we got dynamic power control. If dynamic power control isn't working for some people we should fix that, but supporting nouveau.runpm=0 and manual power control is so far down the list of things I care about. Dave.
