[Mesa-dev] [PATCH 1/3] r600: force LOD range to be only one value when mip.min filter is NONE

[Gert Wollny]

For a texture that has only one LOD defined, but for which
GL_TEXTURE_MAX_LEVEL is the default (1000) and
GL_TEXTURE_MIN_LOD != GL_TEXTURE_MAX_LOD the reading from the texture does
not properly resolve the LOD level and texture lookup might fail. Hence,
when no mipmap filter is given (indicating that no mip-mapping takes place),
force the LOD range to contain only value.

Fixes:
  dEQP-GLES3.functional.shaders.texture_functions.texture*.(i|u)sampler2d*
  dEQP-GLES3.functional.texture.format.sized.cube.rgb*
  out of VK_GL_CTS/android/cts/master/gles3-master.txt
Signed-off-by: Gert Wollny <gw.fossdev at gmail.com>
---
 src/gallium/drivers/r600/evergreen_state.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/gallium/drivers/r600/evergreen_state.c b/src/gallium/drivers/r600/evergreen_state.c
index 5e5e3a0324..b6a01622e4 100644
--- a/src/gallium/drivers/r600/evergreen_state.c
+++ b/src/gallium/drivers/r600/evergreen_state.c
@@ -575,14 +575,22 @@ static void *evergreen_create_sampler_state(struct pipe_context *ctx,
 	unsigned max_aniso = rscreen->force_aniso >= 0 ? rscreen->force_aniso
 						       : state->max_anisotropy;
 	unsigned max_aniso_ratio = r600_tex_aniso_filter(max_aniso);
+	float max_lod = state->max_lod;
 
 	if (!ss) {
 		return NULL;
 	}
 
+	/* If the min_mip_filter is NONE, then the texture has no mipmapping and
+	 * MIP_FILTER will also be set to NONE. However, if more then one LOD is
+	 * configured, then the texture lookup seems to fail for some specific texture
+	 * formats. Forcing the number of LODs to one in this case fixes it. */
+	if (state->min_mip_filter == PIPE_TEX_MIPFILTER_NONE)
+		max_lod = state->min_lod;
+
 	ss->border_color_use = sampler_state_needs_border_color(state);
 
-	/* R_03C000_SQ_TEX_SAMPLER_WORD0_0 */
+        /* R_03C000_SQ_TEX_SAMPLER_WORD0_0 */
 	ss->tex_sampler_words[0] =
 		S_03C000_CLAMP_X(r600_tex_wrap(state->wrap_s)) |
 		S_03C000_CLAMP_Y(r600_tex_wrap(state->wrap_t)) |
@@ -596,7 +604,7 @@ static void *evergreen_create_sampler_state(struct pipe_context *ctx,
 	/* R_03C004_SQ_TEX_SAMPLER_WORD1_0 */
 	ss->tex_sampler_words[1] =
 		S_03C004_MIN_LOD(S_FIXED(CLAMP(state->min_lod, 0, 15), 8)) |
-		S_03C004_MAX_LOD(S_FIXED(CLAMP(state->max_lod, 0, 15), 8));
+		S_03C004_MAX_LOD(S_FIXED(CLAMP(max_lod, 0, 15), 8));
 	/* R_03C008_SQ_TEX_SAMPLER_WORD2_0 */
 	ss->tex_sampler_words[2] =
 		S_03C008_LOD_BIAS(S_FIXED(CLAMP(state->lod_bias, -16, 16), 8)) |
-- 
2.16.4