Re: [PATCH] drm/msm/dpu: Add UBWC support for RGB8888 formats

[Eric Anholt <eric@anholt.net>]

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Rob Clark <robdclark@gmail.com> writes:

> On Wed, Nov 6, 2019 at 3:26 PM Fritz Koenig <frkoenig@google.com> wrote:
>>
>> Hardware only natively supports BGR8888 UBWC.
>> UBWC support for RGB8888 can be had by pretending
>> that the buffer is BGR.
>
> Just to expand, this aligns with how we handle RGB component order in
> mesa for tiled or tiled+ubwc.  If uncompressed to linear the component
> order is RGB, but in tiled or tiled+ubwc, the component order is
> always the hw "native" order (BGR) regardless of what the outside
> world thinks.  But that detail kinda doesn't matter, it's not like
> generic code is going to understand the tiled or tiled+ubwc format in
> the first place.. and code that does understand it, knows enough to
> know that tiled/tiled+ubwc is always in the native component order.
>
>> Signed-off-by: Fritz Koenig <frkoenig@google.com>
>
> Reviewed-by: Rob Clark <robdclark@gmail.com>

Seems like a reasonable workaround to me, and permissible by our fourcc
modifier rules ("you just have to have one way to address the pixels
given a fourcc and a modifier").

Reviewed-by: Eric Anholt <eric@anholt.net>

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