From ec7a33af58dbf421c58dfcc65c680e9c2f1ce09a Mon Sep 17 00:00:00 2001 From: "Juan A. Suarez Romero" Date: Tue, 9 Apr 2019 15:28:42 +0000 Subject: [PATCH] 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 does not clarify how many bits the hardware use. For the mipmap case, there is the following reference in PRM Volume 6 (3D Media GPGPU), specifically in LOD Computation Pseudocode: ``` Bias: S4.8 MinLod: U4.8 MaxLod: U4.8 Base: U4.1 MIPCnt: U4 SurfMinLod: U4.8 ResMinLod: U4.8 `` We have other clues, though: - 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. CC: Jason Ekstrand CC: Lionel Landwerlin Reviewed-by: Lionel Landwerlin --- src/intel/vulkan/anv_device.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/intel/vulkan/anv_device.c b/src/intel/vulkan/anv_device.c index 9d4f93c..88b34c4 100644 --- a/src/intel/vulkan/anv_device.c +++ b/src/intel/vulkan/anv_device.c @@ -1147,8 +1147,8 @@ void anv_GetPhysicalDeviceProperties( 16 * devinfo->max_cs_threads, }, .subPixelPrecisionBits = 8, - .subTexelPrecisionBits = 4 /* FIXME */, - .mipmapPrecisionBits = 4 /* FIXME */, + .subTexelPrecisionBits = 8, + .mipmapPrecisionBits = 8, .maxDrawIndexedIndexValue = UINT32_MAX, .maxDrawIndirectCount = UINT32_MAX, .maxSamplerLodBias = 16, -- 2.7.4