[Mesa-dev] [PATCH v3 5/7] radeonsi: Implement DCC fast clear.

[Bas Nieuwenhuizen]

On Thu, Oct 22, 2015 at 12:12 PM, Marek Olšák <maraeo at gmail.com> wrote:
>> diff --git a/src/gallium/drivers/radeonsi/si_descriptors.c b/src/gallium/drivers/radeonsi/si_descriptors.c
>> index 5548cba3..a277fa5 100644
>> --- a/src/gallium/drivers/radeonsi/si_descriptors.c
>> +++ b/src/gallium/drivers/radeonsi/si_descriptors.c
>> @@ -234,7 +234,7 @@ static void si_set_sampler_views(struct pipe_context *ctx,
>>                         } else {
>>                                 samplers->depth_texture_mask &= ~(1 << slot);
>>                         }
>> -                       if (rtex->cmask.size || rtex->fmask.size) {
>> +                       if (rtex->cmask.size || rtex->fmask.size || rtex->surface.dcc_enabled) {
>>                                 samplers->compressed_colortex_mask |= 1 << slot;
>
> I'd like this flag to be set only when dirty_level_mask is non-zero.
> Setting this for all textures that have DCC is quite expensive in draw
> calls.

I think this code is incorrect even without considering DCC. If we do
a fast clear on a surface which allocates a cmask and then use that
surface as a texture without calling set_sampler_views in between
(because it was bound before) we get a stale compressed_colortex_mask.

Some testing shows that this can be triggered using OpenGL, although
the GL_ARB_texture_barrier extension may be needed to make the result
not undefined per the specification.