[Mesa-dev] Testing drm_hwcomposer in RPi

[Stefan Schake]

Hey Chris,

On Fri, Jun 22, 2018 at 12:09 PM, chris simmonds <smoog11 at googlemail.com> wrote:
> Hi.
>
> I would like to try out drm_hwcomposer on a RPi 3. Can anyone point me to a
> howto or something that tells me how?
>
> FYI, this is part of a side project to port drm_hwcomposer to BeagleBones
> and other things based on TI SoCs
>
> Thanks,
> Chris Simmonds

So Mesa is really only transitively related to drm_hwc, in that you need
a graphics driver with Android native fence support. For Mesa and the VC4
GPU on the RPi specifically, that's supported in a very recent Mesa version
in combination with a very recent kernel that has the VC4 syncobj support.
The earliest kernel version that has this is 4.18-rc1, but it can be
backported relatively painlessly to 4.14, which is what the android-kernel
tree uses and works on Oreo upwards. No released Mesa version has the
support yet, but master can be made to work with AOSP.

As you can tell, there is no howto or anything - this is all pretty
bleeding edge and you'll need to do some indepth sleuthing to get it
to work. If you hit any specific problems, the best point to get help
is the drm-hwcomposer project on the freedesktop gitlab:

https://gitlab.freedesktop.org/drm-hwcomposer/drm-hwcomposer

Thanks,
Stefan