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

[Vikas Patil]

On Fri, Jun 9, 2017 at 1:16 PM, Pekka Paalanen <ppaalanen at gmail.com> wrote:
>
> 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.

Thanks a lot for your quick comments.

What are the fitting criteria for mapping surfaces to plane
automatically? What happens if number of surfaces are more than
available planes, which surface gets the plane (in case some specific
application desire to use plane not the other apps)? We have a use
case where we want multiple applications to use the particular plane
only?

How the other h/w features for planes (z-order, global alpha, rotation
) are handled with this? Is there any way to utilize this also?

> 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.
>
I could give a try but not sure if the kernel from TI BSP (4.4.23)
supports atomic mode setting (generic and TI SoC specific if any). How
to to check if atomic mode setting is supported or not in kernel? Do I
also need to update the wayland/weston to latest version or I can
apply the patches to 1.11.0? I also need to know how to test then if
able to apply the patches and run the weston? Which version of
Wayland-ivi-extension I need to use with these patches or first need
to tested with desktop-shell?

I found the patches at https://phabricator.freedesktop.org/T7595 but
it would be helpful to get the branch details. I see this patches are
tested again intel and rockchip hw. Are they generic and supposed to
work on other SoCs (DRA7XX TI) or some feature required to be
supported in kernel/bsp to utilize this?

Thanks & Regards,
Vikash