[Mesa-dev] [PATCH v3 2/2] anv: advertise 8 subpixel precision bits

[Juan A. Suarez Romero]

On one side, when emitting 3DSTATE_SF, VertexSubPixelPrecisionSelect is
used to select between 8 bit subpixel precision (value 0) or 4 bit
subpixel precision (value 1). As this value is not set, means it is
taking the value 0, so 8 bit are used.

On the other side, in the Vulkan CTS tests, if the reference rasterizer,
which uses 8 bit precision, as it is used to check what should be the
expected value for the tests, is changed to use 4 bit as ANV was
advertising so far, some of the tests will fail.

So it seems ANV is actually using 8 bits.

v2: explicitly set 3DSTATE_SF::VertexSubPixelPrecisionSelect (Jason)
v3: use _8Bit definition as value (Jason)

CC: Jason Ekstrand <jason at jlekstrand.net>
CC: Kenneth Graunke <kenneth at whitecape.org>
Signed-off-by: Juan A. Suarez Romero <jasuarez at igalia.com>
---
 src/intel/vulkan/anv_device.c    | 2 +-
 src/intel/vulkan/genX_pipeline.c | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/intel/vulkan/anv_device.c b/src/intel/vulkan/anv_device.c
index 3120865466a..95224407318 100644
--- a/src/intel/vulkan/anv_device.c
+++ b/src/intel/vulkan/anv_device.c
@@ -1095,7 +1095,7 @@ void anv_GetPhysicalDeviceProperties(
          16 * devinfo->max_cs_threads,
          16 * devinfo->max_cs_threads,
       },
-      .subPixelPrecisionBits                    = 4 /* FIXME */,
+      .subPixelPrecisionBits                    = 8,
       .subTexelPrecisionBits                    = 4 /* FIXME */,
       .mipmapPrecisionBits                      = 4 /* FIXME */,
       .maxDrawIndexedIndexValue                 = UINT32_MAX,
diff --git a/src/intel/vulkan/genX_pipeline.c b/src/intel/vulkan/genX_pipeline.c
index 6255e5d83c5..3d36bb773e1 100644
--- a/src/intel/vulkan/genX_pipeline.c
+++ b/src/intel/vulkan/genX_pipeline.c
@@ -464,6 +464,7 @@ emit_rs_state(struct anv_pipeline *pipeline,
    sf.TriangleStripListProvokingVertexSelect = 0;
    sf.LineStripListProvokingVertexSelect = 0;
    sf.TriangleFanProvokingVertexSelect = 1;
+   sf.VertexSubPixelPrecisionSelect = _8Bit;
 
    const struct brw_vue_prog_data *last_vue_prog_data =
       anv_pipeline_get_last_vue_prog_data(pipeline);
-- 
2.20.1