[RFC] drm: Introduce max width and height properties for planes

[Daniel Vetter]

On Mon, May 30, 2016 at 09:47:53AM -0400, Rob Clark wrote:
> On Mon, May 30, 2016 at 5:32 AM, Daniel Vetter <daniel at ffwll.ch> wrote:
> > drm_hwcomposer (developed by Google) is a generic hwc implementation along
> > the lines of weston and any other generic kms compositor. I think it makes
> > a lot of sense to aim for a reasonable baseline API which works the same
> > way everywhere. And that reasonable baseline abi imo includes that at
> > least 1 plane can be used full-screen, without jumping through hooks.
> >
> > Because if you don't have that, then it's not just weston and android you
> > need to patch up. But also
> > - fbdev
> > - any boot splash
> > - any igt testcases (I'm starting to push hard to make those a requirement
> >   for kms drivers)
> > - X
> > - any other compositor, like mutter, kwin, ozone, ...
> 
> I think it's not so bad.  We fix the setcrtc helpers to do this for
> legacy crtc path (which should pretty much cover most existing
> compositors, X, splash, fbdev, etc).  After all they already pick one
> plane, it shouldn't be too hard to make them pick two.
> 
> But for atomic, we make userspace deal with it, since things get more
> complicated than what setcrtc/pageflip has to deal with.  Afaiu there
> are basically two atomic compositors (and the weston one isn't even
> merged), so I think dealing with this in userspace is not so bad.

What exactly is more complicated with doing this for full atomic? If you
do it in userspace for setcrtc, plus fbdev, plus
weston/ozone/drm_hwcomposer/ and maybe more, then that's already an
impressive pile of copies of that logic. And I really think it should be
pretty simple to type this up into a helper that works on any plane.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch