Wayland on Embedded

[Pekka Paalanen]

On Wed, 21 Nov 2012 12:36:45 +0530
Abhijit Potnis <abhijitpotnis at gmail.com> wrote:

> On Wed, Nov 21, 2012 at 12:23 PM, Pekka Paalanen <ppaalanen at gmail.com>wrote:
> 
> > On Wed, 21 Nov 2012 11:38:57 +0800
> > Henius Dong <donglw at pset.suntec.net> wrote:
> >
> > > Hi Abhijit
> > >
> > > -----Original Message-----
> > > From: Abhijit Potnis
> > > Sent: 2012/11/20 15:04
> > >
> > > > On Mon, Nov 19, 2012 at 3:34 PM, Henius Dong <donglw at pset.suntec.net
> > > > <mailto:donglw at pset.suntec.net>> wrote:
> > > >
> > > >     Hello Abhijit
> > > >
> > > >     I saw the topic "Wayland on Embedded" in wayland-devel mailing
> > list.
> > > >     I'm interested in this topic too. But, I'm naive in this topic now.
> > > >     So, I write a mail to you to see whether you could give me some
> > > >     hints or not?
> > > >
> > > >     Now, I'm going to port the wayland onto freescale iMX6 board. It
> > > >     supports Linux/WinCE/Android OS. I want to use the Linux OS
> > > >     "without" DRM support. So, it going to be difficult to use the
> > > >     compositor-drm.
> > > >     But, freescale offers the GLES2 implementation. So, I wonder I
> > might
> > > >     need the same GLES2 >> framebuffer back-end.
> > > >
> > > >
> > > > Freescale iMX6 driver releases do show that they now support drm in
> > > > their kernel. You may want to try that.
> > > > But as such writing a GLES2 over FB backend will work, but with
> > > > restricted features as listed in the
> > > > below mail chain. With much of the work now abstracted by
> > gles2-renderer
> > > > (gl-renderer as its called now) , it must be simple enough to write the
> > > > back-end.
> > > Thanks for your information. I would confirm with Freescale.
> > >
> > > >
> > > >     Could you give me some help?
> > > >     Anything is welcome.
> > > >
> > > > This will be of some help
> > > > <
> > http://lists.freedesktop.org/archives/wayland-devel/2012-September/005324.html
> > >
> > > I've checked this mail chain. The "restricted features" you mentioned is
> > > I won't able to run GL client by using GLES2 over FB backend, right? But
> > > since iMX6 has the DRM support, using DRM backend may be easier.
> >
> > Whether or not Wayland clients that use GL will work, essentially
> > depends on libEGL, and not really about the backend the compositor is
> > using. In fact, client support and compositor backend are orthogonal.
> > They only need to be compatible in the sense, that what clients
> > provide, the compositor can use.
> >
> > LibEGL is the standard place to implement the support for clients that
> > use GL, but nothing prevents you from inventing your own way, if you
> > control all the applications. Qt5 AFAIU supports its own thing, and so
> > it is not dependant on libEGL's Wayland platform support.
> >
> > The Freescale driver release does have a few Wayland definitions
> in their header files. But no document explaining if they support Wayland/
> Weston. Also there is no explicit mention from freescale that they have
>  Wayland EGL platform ( wayland-egl API) implemented.
> 
> Correct me if I am wrong, with this scenario: we will have to end up
> writing a
> EGL wrapper for their proprietary driver to handle buffers. Or invent ones
> on way.

You're probably right. But the very first thing you have to do is to
find out, if there is a way to pass gfx buffers from one process that
renders into it, to another process that uses it as a texture or
pushes it to the screen somehow. Once you know that, and know what the
buffer handles are, you can start looking at how to use a Wayland
protocol extension to send buffer handles, and then how to wrap it all
in your own libEGL.

Déjà vu, I think I just explained the same thing to someone on #wayland
last evening. :-P Clearly a blog-worthy topic...


Thanks,
pq