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

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Thu, 21 Jul 2011 19:30:00 +0900
Joonyoung Shim <dofmind@gmail.com> wrote:

> Hi,
> 
> simple questions :)
> 
> 2011/6/21 Jesse Barnes <jbarnes@virtuousgeek.org>:
> > Planes are a bit like half-CRTCs.  They have a location and fb, but
> > don't drive outputs directly.  Add support for handling them to the core
> > KMS code.
> >
> > Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
> > ---
> >  drivers/gpu/drm/drm_crtc.c |  235 +++++++++++++++++++++++++++++++++++++++++++-
> >  drivers/gpu/drm/drm_drv.c  |    3 +
> >  include/drm/drm.h          |    3 +
> >  include/drm/drm_crtc.h     |   73 ++++++++++++++-
> >  include/drm/drm_mode.h     |   35 +++++++
> >  5 files changed, 346 insertions(+), 3 deletions(-)
> >
> 
> snip
> 
> > diff --git a/include/drm/drm_mode.h b/include/drm/drm_mode.h
> > index c4961ea..fa6d348 100644
> > --- a/include/drm/drm_mode.h
> > +++ b/include/drm/drm_mode.h
> > @@ -120,6 +120,41 @@ struct drm_mode_crtc {
> >        struct drm_mode_modeinfo mode;
> >  };
> >
> > +/* Planes blend with or override other bits on the CRTC */
> > +struct drm_mode_set_plane {
> > +       __u32 plane_id;
> > +       __u32 crtc_id;
> > +       __u32 fb_id; /* fb object contains surface format type */
> > +
> > +       /* Signed dest location allows it to be partially off screen */
> > +       __s32 crtc_x, crtc_y;
> 
> Is this location offset from base(0, 0) of fb for plane, or from base
> of crtc(mode)?

This is the offset on the crtc specifically (which could be displaying
a nonzero offset of a given fb).

> 
> > +       __u32 crtc_w, crtc_h;
> 
> What is it for? size of plane?

These are the size of the rect on the crtc.  It's possible to have say
a small source fb that gets scaled to a different size on the crtc by
the plane blender or display hardware.

> 
> > +
> > +       /* Source values are 16.16 fixed point */
> > +       __u32 src_x, src_y;
> > +       __u32 src_h, src_w;
> 
> What are these for?

These specify the offset and size of the rect used for the source
area.  This allows the sprite hardware to send a subregion to the plane
blender for display on the crtc.

> > +
> > +       __u32 zpos;
> 
> Is this for order of plane(overlay)?

Yes.

Hope that helps; most of the above came out of earlier review comments
since some display hardware allows a lot of flexibility when displaying
overlay planes.

-- 
Jesse Barnes, Intel Open Source Technology Center