anv: advertise 8 subtexel/mipmap precision bits (!599) · Merge requests · Mesa / mesa

So far ANV was advertising 4 bits for both subTexelPrecisionBits and mipmapPrecisionBits. But these values were not actually verified.

But it seems the right value is actually 8 bits for both cases.

Unfortunately Intel PRM is does not clarify how many bits the hardware use. But we have a couple of clues:

On one side, dEQP-VK.texture.explicit_lod.* tests fail when using 4 bits, but work when using 8 bits. These tests try to mimic the expected behaviour as much real as possible, and they use the reported subTexelPrecisionBits and mipmapPrecisionBits reported to get this.
On the other side, the equivalent driver for Windows is reporting 8 bits for both elements. Not sure if they got to verify it from the PRM or from a diffent source.

anv: advertise 8 subtexel/mipmap precision bits