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

[Marek Olšák]

On Fri, Oct 23, 2015 at 1:57 PM, Bas Nieuwenhuizen
<bas at basnieuwenhuizen.nl> wrote:
> On Fri, Oct 23, 2015 at 1:52 PM, Marek Olšák <maraeo at gmail.com> wrote:
>> On Fri, Oct 23, 2015 at 1:30 PM, Bas Nieuwenhuizen
>> <bas at basnieuwenhuizen.nl> wrote:
>>> On Fri, Oct 23, 2015 at 12:50 PM, Marek Olšák <maraeo at gmail.com> wrote:
>>>> On Fri, Oct 23, 2015 at 12:17 PM, Bas Nieuwenhuizen
>>>> <bas at basnieuwenhuizen.nl> wrote:
>>>>> 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.
>>>>
>>>> In that case, we should decompress in texture_barrier and not in draw calls.
>>>>
>>>> Marek
>>>
>>>
>>> texture_barrier does not need to be called though, the language
>>> changes might be needed.
>>>
>>> Basically the test is
>>>
>>> fbo1, fbo2 framebuffers with 1 color buffer each:
>>>
>>> bind fbo2 as texture
>>> clear fbo1 using shader
>>> bind fbo1 as texture
>>> clear fbo2 using shader
>>> clear fbo1 using clear (which results in cmask being allocated for fbo1)
>
>>> bind fbo2 as texture
>>> copy fbo2 to fbo1 using copy shader (which wrongly does not decompress fbo1)
>
> My apologies, these two lines should just be a copy fbo1 to fbo2,
> which does need to eleminate the cmask fast clear.

That sounds like a texture barrier is required.

Marek