Re: [PATCH 1/4] drm: add plane support

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Fri, 22 Jul 2011 08:52:52 -0500
Rob Clark <robdclark@gmail.com> wrote:

> On Mon, Jun 20, 2011 at 3:11 PM, Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> >  /**
> > + * drm_plane_funcs - driver plane control functions
> > + * @update_plane: update the plane configuration
> > + */
> > +struct drm_plane_funcs {
> > +       int (*update_plane)(struct drm_plane *plane,
> > +                           struct drm_crtc *crtc, struct drm_framebuffer *fb,
> > +                           int crtc_x, int crtc_y,
> > +                           unsigned int crtc_w, unsigned int crtc_h,
> > +                           uint32_t src_x, uint32_t src_y,
> > +                           uint32_t src_w, uint32_t src_h);
> > +       void (*disable_plane)(struct drm_plane *plane);
> > +};
> > +
> 
> 
> would it freak anyone out too much to ask about multi-planar formats?
> Ie. say you have an overlay that could display I420 w/ separate Y, U,
> & V addresses or NV12 w/ separate Y and UV addresses.  Some of the
> SoC's out there require that chroma and luma is in different memory
> banks.  In omap4xxx case we don't have this requirement, but we do
> have different tiling for Y and UV  (NV12).
> 
> Not something that directly affects this patchset.. I'm thinking more
> along the lines of having a way to create a drm_framebuffer w/ more
> than one GEM buffer, one per color plane.  The other option is to bury
> this all behind a single GEM buffer.. although that seems like it
> could get ugly/hacky.
> 
> Am I opening a can of worms here?  ;-)

Yes. :)

Given the format constraints for planar, multi-buffer configs, it might
be best to expose those as driver specific ioctls.  It's a big ugly to
have a driver specific addfb (only because we don't have one currently)
but should be doable for funkier things like this.

-- 
Jesse Barnes, Intel Open Source Technology Center