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

Bastien Nocera hadess at hadess.net
Thu Mar 10 15:29:28 UTC 2016

Hey Dave,

On Thu, 2016-03-10 at 09:30 +1000, Dave Airlie wrote:
> Okay so I'm not sure you are heading in the best direction here.
> My first suggestion is to stop using the MBP, start using the Lenovo.
> At least from a Fedora perspective, that is the hw we have more
> installs of and
> care more about.

The Lenovo has an NVidia GPU, and there's no runtime PM support for

> Apple HW is not the same as PC hw in this case and we aren't going to
> achieve
> the same level of integration that OSX has, not without some serious
> rewrites of
> mutter and the whole X stack.

That's not the target goals. Did you read the wiki page I pointed to
listing the goals?


> You shouldn't be caring about the MUX.

I never talked about the MUX, didn't plan on using it either.


> So I'm missing what the overall goal here is. To provide better
> support for dual-gpu
> laptops and hotpluggable USB devices in the DE?

Just dual-GPU devices for now.

I'd be interested in supporting USB displays, but I only have
proprietary drivers for my USB3 DisplayLink dock, and possibly
networked display devices, but the AirTame I have is also still using
an undocumented protocol.

> Under X, Fedora carries a server patch to autoconfigure providers,
> we'd need to drop
> that and have something in the DE notice when a new provider shows up
> and configures it,
> perhaps something to allow removal of providers that are already
> bound
> (so we could detach
> a secondary GPU for boxes to passthrough).

I'd rather have that be automated so that Boxes can tell you what is
using the 2nd GPU, not requiring any manual intervention.

> Then we need something in the DE to allow us to launch or have some
> app info that would
> decide to launch certain 3D using apps on the more powerful
> processor.

That's what I started working on, exporting the fact that 2 GPUs are
available through a D-Bus service, which also ensures that we only 

> However since
> nouveau doesn't quite reclock most of the secondary GPUs that can
> often end up not being
> that much more powerful.

There are supported laptops with Radeon GPUs as well, not sure whether
that's more powerful.

> We also want reverse prime to work properly, so if you plug in an
> external monitor to
> a port connected to the secondary GPU that we can pick it up and
> configure it just like
> all the other monitors.

I don't think I have any hardware that works this way.

> As for the MBP, if we want to spend time chasing the rainbow of OS X,
> then we've a lot of work
> to do. OSX can smoothly switch the compositor from rendering on the
> intel gpu to the nvidia
> gpu in a vblank. It's truly seamless. To do that we'd need to a) move
> to wayland, b) get mutter
> to be a lot smarter than mutter currently is.

That's not what I'm aiming for right now.


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