[PATCH 02/23] drm: omapdrm: fb: Don't store format BPP for each plane

[Rob Clark]

On Mon, May 2, 2016 at 11:43 AM, Tomi Valkeinen <tomi.valkeinen at ti.com> wrote:
> Hi Laurent,
>
> On 26/04/16 23:35, Laurent Pinchart wrote:
>> The number of bits per pixel is identical for all planes, don't store
>> multiple copies.
>
> That's not true, as with NV12, Y has 8 bits per pixel and UV has 16 bits
> per pixel. But as the subsampling is precalculated into the stride_bpp
> (is it bytes or bits? bpp always confuses me =), the 'stride_bpp' ends
> up being same for both planes.
>
> To be honest, I'd rather go into more complex struct than simpler one.
> The current one is already confusing, I think, and your version is too.
> The main issue is that the sub_x is encoded into the stride_bpp. In
> kmsxx I used this format:
>
> { PixelFormat::NV12, { 2, { { 8, 1, 1, }, { 8, 2, 2 } }, } },
>
> The first number is the number of planes, and for each plane, bitspp,
> xsub and ysub. It's more verbose, but (I think) easier to understand.

fwiw, I guess a lot of data from that table could these days be
replaced w/ some of the drm format helpers
(drm_format_num_planes()/drm_format_plane_cpp()/drm_format_{horz,vert}_chroma_subsampling()/etc)

BR,
-R

>  Tomi
>