[Mesa-dev] [PATCH 2/4] gallium/radeon: don't discard DCC if an external user can write to it

[Marek Olšák]

On Mon, Jun 6, 2016 at 5:12 PM, Bas Nieuwenhuizen
<bas at basnieuwenhuizen.nl> wrote:
> On Mon, Jun 6, 2016 at 4:21 PM, Nicolai Hähnle <nhaehnle at gmail.com> wrote:
>> On 06.06.2016 16:16, Nicolai Hähnle wrote:
>>>
>>> Patches 1 & 2:
>>>
>>> Reviewed-by: Nicolai Hähnle <nicolai.haehnle at amd.com>
>>
>>
>> Hold off on patch #2 - how does this work together with shader image writes?
>> Then we're in an ugly situation where the other process could write to DCC,
>> but we still need to decompress while the texture is bound as a shader
>> image? That doesn't sound good to me...
>
> Does this ever happen anyway? If we have an external writer and this
> process writes (due to binding it for image write) then at least one
> process did an export with write usage which should disable DCC. So I
> don't think we can ever get in this situation.

While I agree with you, let's be safe than sorry and so v2 does a
decompression pass.

Marek