[Intel-gfx] [PATCH v5 00/12] Enable GPU switching on pre-retina?MacBook Pro

[Dave Airlie]

>
> I guess that's only useful until we get runtime PM support.

For the discrete GPUs on regular laptops we have runtime PM support for
powerdown already. Some newer laptops need a bit of work in the PCIE layer
but for most things we have it covered. The known broken ones are Apple
laptops. If the apple-gmux code is working well enough to power off GPUs,
then it should be possible to hook up runtime-pm on those machines pretty
simply.

So there shouldn't really be a case we care about.

runtime PM for the Intel GPU isn't as important. We don't even want to
turn the i915 fully off anymore.

>
> After looking at our use cases in the GNOME wiki, I think that might
> not be necessary as we'll want to always run the desktop on the
> integrated GPU. That'll something to keep in mind if we ever want to
>
> Reading through the whole mail it seems to me that it's close to
> impossible to implement a decent integration without runtime PM
> support:
> - DRI_PRIME wouldn't work
> - no external display detection on some machines
>
> Do you have references for the i915 runtime PM support, a bugzilla or
> mailing-list thread?

the i915 runtime PM doesn't matter for this. Only nouveau/radeon runtime
PM matters for this, and that should work on most Windows compatible hw right
now. For Windows 10 machines there are some patches going around to make
things work. For Apple I'm pretty much in the it'll catch up or it
won't, but don't
block on it.

Dave.