[Mesa-dev] [PATCH 2/2] i965: Respect driconf option clamp_max_samples

[Chad Versace]

Clamp gen7 GL_MAX_SAMPLES to 0, 4, or 8.
Clamp gen6 GL_MAX_SAMPLES to 0 or 4.
Clamp other gens to 0.

CC: Eric Anholt <eric at anholt.org>
Signed-off-by: Chad Versace <chad.versace at linux.intel.com>
---
 src/mesa/drivers/dri/i965/brw_context.c  | 35 +++++++++++++++++++++++---------
 src/mesa/drivers/dri/i965/intel_screen.c |  1 +
 2 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 38147e9..60a201f 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -273,6 +273,10 @@ brw_initialize_context_constants(struct brw_context *brw)
 {
    struct gl_context *ctx = &brw->ctx;
 
+   uint32_t max_samples;
+   const uint32_t *legal_max_samples;
+   uint32_t clamp_max_samples;
+
    ctx->Const.QueryCounterBits.Timestamp = 36;
 
    ctx->Const.StripTextureBorder = true;
@@ -333,19 +337,30 @@ brw_initialize_context_constants(struct brw_context *brw)
 
    ctx->Const.AlwaysUseGetTransformFeedbackVertexCount = true;
 
-   if (brw->gen == 6) {
-      ctx->Const.MaxSamples = 4;
-      ctx->Const.MaxColorTextureSamples = 4;
-      ctx->Const.MaxDepthTextureSamples = 4;
-      ctx->Const.MaxIntegerSamples = 4;
-   } else if (brw->gen >= 7) {
-      ctx->Const.MaxSamples = 8;
-      ctx->Const.MaxColorTextureSamples = 8;
-      ctx->Const.MaxDepthTextureSamples = 8;
-      ctx->Const.MaxIntegerSamples = 8;
+   if (brw->gen >= 7) {
+      legal_max_samples = (uint32_t[]){8, 4, 0};
       ctx->Const.MaxProgramTextureGatherComponents = 4;
+   } else if (brw->gen == 6) {
+      legal_max_samples = (uint32_t[]){4, 0};
+   } else {
+      legal_max_samples = (uint32_t[]){0};
+   }
+
+   /* Set max_samples = min(max(legal_max_samples), clamp_max_samples). */
+   max_samples = 0;
+   clamp_max_samples = driQueryOptioni(&brw->optionCache, "clamp_max_samples");
+   for (uint32_t i = 0; legal_max_samples[i] != 0; ++i) {
+      if (legal_max_samples[i] <= clamp_max_samples) {
+         max_samples = legal_max_samples[i];
+         break;
+      }
    }
 
+   ctx->Const.MaxSamples = max_samples;
+   ctx->Const.MaxColorTextureSamples = max_samples;
+   ctx->Const.MaxDepthTextureSamples = max_samples;
+   ctx->Const.MaxIntegerSamples = max_samples;
+
    ctx->Const.MinLineWidth = 1.0;
    ctx->Const.MinLineWidthAA = 1.0;
    ctx->Const.MaxLineWidth = 5.0;
diff --git a/src/mesa/drivers/dri/i965/intel_screen.c b/src/mesa/drivers/dri/i965/intel_screen.c
index eafafa2..0e991ec 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.c
+++ b/src/mesa/drivers/dri/i965/intel_screen.c
@@ -67,6 +67,7 @@ DRI_CONF_BEGIN
    DRI_CONF_SECTION_END
    DRI_CONF_SECTION_QUALITY
       DRI_CONF_FORCE_S3TC_ENABLE("false")
+      DRI_CONF_CLAMP_MAX_SAMPLES()
    DRI_CONF_SECTION_END
    DRI_CONF_SECTION_DEBUG
       DRI_CONF_NO_RAST("false")
-- 
1.8.3.1