[Intel-gfx] [PATCH igt] tools/null_state_gen: Don't upload color calc and depth stencil on gen6

[Mika Kuoppala]

Chris Wilson <chris at chris-wilson.co.uk> writes:

> Quoting Mika Kuoppala (2017-08-08 14:36:59)
>> Mika Kuoppala <mika.kuoppala at linux.intel.com> writes:
>> 
>> > We were pointing the color calc and depth stencil states blindly
>> > to an offset of 1k from bb start. This was foolhardy as it collides
>> > with other state in the batch and results in a wrecked state upload.
>> >
>> > Chris noticed that with snb gt1, it takes 10 seconds for renderstate batch
>> > to complete. However pointing the states to a known valid 64 aligned
>> > zero blocks didn't work to reduce the upload time either.
>> >
>> > Cave in and omit uploading color calc and depth stencil states.
>> 
>> Not just yet, ignore this patch.
>
> Right, we found the root cause for my issue, so we can actually load the
> correct state here (i.e. create a NUL block and point both depth-stencil
> and color-calc to it). We could use that same block for the blend state
> as well, etc.

I chose to keep the blend state as is, for the first step. As the blend
state is is not all zeros. But after the patch to add cc and depth
stencil states as null, it is a minor step, as in code, to nullify the
blend state also.

-Mika

> -Chris