drm pixel formats update

[Ville Syrjälä]

On Wed, Nov 16, 2011 at 07:54:12PM +0000, Alan Cox wrote:
> > If anyone has problems with the way the formats are defined, please
> > speak up now! Since only Jesse has bothered to comment on my rantings
> > I can only assume people are happy with my approach to things.
> 
> Umm .. no. I don't see why they are needed. Its just an extra layer of
> gratuitious confusing indirection. The rest of the world speaks and
> understands FourCC sp for all the formats covered by an existing FourCC
> name we should just the existing name.
> 
> You might need to check one now and then but everyone doing video
> processing is familiar with them including all the Windows folk.

I think the only format in my list where I didn't use an existing fourcc
is I420/IYUV. And BTW, for that one I used the same "fake" fourcc that
v4l2 uses (YU12). 

And that brings another matter to the table. How should we deal with
duplicate fourccs? I420/IYUV and YUY2/YUYV come to mind.

Also, if I now add these ad-hoc fourccs for the RGB formats, and some
time later someone comes in with a format with a conflicting official
fourcc, what should we do?

Oh and one extra detail just occured to me regarding the three plane
formats. Should we even define formats for both the YUV vs. YVU
variant. Seeing as we now have independent handles and offsets for
each plane, we can make do with just one format definition.

-- 
Ville Syrjälä
Intel OTC