[Mesa-dev] [PATCH 2/2] i965: Bump BRW_MAX_TEX_UNIT to 32.

[Ian Romanick]

On 01/17/2014 01:08 PM, Marek Olšák wrote:
> The test seems to work correctly with 32 textures per stage. It tests
> that all textures return the correct color, but the sampler state is
> always the same.

Which is the problem.  The method we're using to access samplers works
fine for up to 16, but fails after that... by dropping the high-order
index bits.  If all the samplers are the same, the test won't notice
that Ken's implementation is garbage. :(

> Marek
> 
> On Thu, Jan 16, 2014 at 1:28 AM, Kenneth Graunke <kenneth at whitecape.org> wrote:
>> On 01/15/2014 12:56 PM, Chris Forbes wrote:
>>> Does this actually work for >16?
>>>
>>> Sampler messages' descriptor only has 4 bits for the sampler index, so
>>> it seems you'd silently lose the top bit and get the wrong sampler
>>> parameters.
>>
>> Oh, wow.  No...no, it can't possibly work then.  (Apparently that Piglit
>> test isn't sufficient...I just glanced at it...)
>>
>> It looks like the Intel Windows driver has bumped this to 32 on Haswell
>> (but not earlier).  I'm guessing that they use the "Sampler State
>> Pointer" field in the message /header/, instead of the "Sampler Index"
>> field in the message /descriptor/.  On Haswell, that changed to be
>> relative to Dynamic State Base Address instead of General State Base
>> Address.  Which probably helps.
>>
>> Still, that's probably going to be kind of miserable.  I'll have to look
>> into what they're doing.
>>
>> NAK on patch 2.
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