How to configure/use/assign hardware pipeline/plane for specific application?

[Pekka Paalanen]

On Fri, 9 Jun 2017 12:31:22 +0530
Vikas Patil <vikasmpatil at gmail.com> wrote:

> Dear All,
> 
> I am using wayland/weston 1.11.0 (with ivi-shell and drm-backend) with
> DRA7xx (TI's automotive SoC) and Linux  4.4. I am investigating on how
> could wayalnd based application can be assigned to use particular pipeline.
> 
> Use-case details:
> As TI's DRA7xx SoC provides 1 graphics and 3 video pipeline (also refereed
> as plane).  For example I would like to assign GFX pipeline to GUI
> application, VID1 pipeline to video player, VID2
> pipeline to camera application and VID3 for some other application.
> 
> I can see currently weston uses only GFX pipeline.  Is there a way to do
> this using wayland/weston? What needs to be done to achieve this?

Hi,

the proper solution is to get the atomic modesetting patch series by
Daniel Stone reviewed, finalized, and merged. This is the foundation
for how weston could use additional DRM planes at all.

Once that is done, the window manager needs to ensure that the
scenegraph is always compatible with putting the surfaces you want on
the DRM planes you want. With ivi-shell that is very possible as you
have unique identification for every application surface. Then, there
might be tweaks needed in the libweston DRM-backend to achieve the
correct automatic surface/plane associations.

The major point here is that one does not explicitly configure a
surface for a DRM plane in Weston or via protocol. The DRM planes will
be used automatically for any surfaces that might fit. Weston's
architecture currently in master (let alone in something as old as
1.11) does not support interactions between the shell
plugin and the backend plugin to explicitly and permanently configure
the DRM plane assignments. It's not inconceivable to add the necessary
infrastructure, but I would see if the implicit approach works first.

If you want to give the patch series a go, I believe Daniel can point
you to the latest branches.


Thanks,
pq
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