anv: advertise 8 subtexel/mipmap precision bits
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:
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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.
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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.
CC: Jason Ekstrand jason@jlekstrand.net CC: Lionel Landwerlin lionel.g.landwerlin@intel.com