[Mesa-dev] [PATCH 2/2] st/mesa: add GL_ARB_shader_atomic_counter_ops support

[Nicolai Hähnle]

On 10.03.2016 12:50, Glenn Kennard wrote:
> On Thu, 10 Mar 2016 18:13:03 +0100, Ilia Mirkin <imirkin at alum.mit.edu>
> wrote:
>
>> On Thu, Mar 10, 2016 at 12:04 PM, Glenn Kennard
>> <glenn.kennard at gmail.com> wrote:
>>> On Thu, 10 Mar 2016 17:02:15 +0100, Ilia Mirkin <imirkin at alum.mit.edu>
>>> wrote:
>>>
>>>> On Thu, Mar 10, 2016 at 10:57 AM, Nicolai Hähnle <nhaehnle at gmail.com>
>>>> wrote:
>>>>>>
>>>>>> -   if (c->MaxCombinedAtomicBuffers > 0)
>>>>>> +   if (c->MaxCombinedAtomicBuffers > 0) {
>>>>>>         extensions->ARB_shader_atomic_counters = GL_TRUE;
>>>>>> +      extensions->ARB_shader_atomic_counter_ops = GL_TRUE;
>>>>>> +   }
>>>>>
>>>>>
>>>>>
>>>>> I believe there's pre-GCN AMD hardware which can support atomic
>>>>> counters
>>>>> but
>>>>> not atomic_counter_ops (at least according to what the closed driver
>>>>> exposes, I haven't actually checked the docs), so there should
>>>>> probably
>>>>> be a
>>>>> capability flag here.
>>>>
>>>>
>>>> I assumed this was due to laziness... seems odd if the SSBO atomic ops
>>>> can be supported, but those same ops can't be supported on atomic
>>>> buffers. Glenn / Dave - do you guys happen to know what the pre-GCN hw
>>>> is capable of?
>>>>
>>>>   -ilia
>>>>
>>>
>>> AFAIK Cayman supports atomic counter ops on SSBOs, evergreen only on
>>> counter
>>> buffers, and earlier hardware does neither.
>>
>> To phrase this a different way, my patch is fine? :) If you support
>> atomic counters, you support all the various ops in
>> ARB_shader_atomic_counter_ops (which are basically all the SSBO ops,
>> but on atomic counters)?
>>
>
> I think so, though the closed driver only exposes
> ARB_shader_atomic_counter_ops on
> Cayman only which may be a hint to something. Cross that bridge when we
> get there...

Fair enough. Ilia, I did take a look at the other parts of patch #2, so 
feel free to add my R-b there as well.

Cheers,
Nicolai

>
> /Glenn