[Mesa-dev] [PATCH 6/8] i965: Fix CS scratch size calculations on Ivybridge and Baytrail.

[Kenneth Graunke]

These are linear, not powers of two, and much more limited.

Cc: "12.0" <mesa-stable at lists.freedesktop.org>
Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/mesa/drivers/dri/i965/brw_fs.cpp      | 6 ++++++
 src/mesa/drivers/dri/i965/gen7_cs_state.c | 6 ++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 8c0ec4e..f1a1c87 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -5995,6 +5995,12 @@ fs_visitor::allocate_registers(bool allow_spilling)
           * and platform.
           */
          prog_data->total_scratch = MAX2(prog_data->total_scratch, 2048);
+      } else if (devinfo->gen <= 7 && stage == MESA_SHADER_COMPUTE) {
+         /* According to the MEDIAVFE_STATE's "Per Thread Scratch Space"
+          * field documentation, platforms prior to Haswell measure scratch
+          * size linearly with a range of [1kB, 12kB] and 1kB granularity.
+          */
+         prog_data->total_scratch = ALIGN(last_scratch, 1024);
       }
    }
 }
diff --git a/src/mesa/drivers/dri/i965/gen7_cs_state.c b/src/mesa/drivers/dri/i965/gen7_cs_state.c
index 42cd61f..9d83837 100644
--- a/src/mesa/drivers/dri/i965/gen7_cs_state.c
+++ b/src/mesa/drivers/dri/i965/gen7_cs_state.c
@@ -79,10 +79,12 @@ brw_upload_cs_state(struct brw_context *brw)
                    I915_GEM_DOMAIN_RENDER, I915_GEM_DOMAIN_RENDER,
                    ffs(prog_data->total_scratch) - 12);
       } else {
-         /* This is wrong but we'll fix it later */
+         /* Earlier platforms use the range [0, 11] to mean [1kB, 12kB]
+          * where 0 = 1kB, 1 = 2kB, 2 = 3kB, ..., 11 = 12kB.
+          */
          OUT_RELOC(stage_state->scratch_bo,
                    I915_GEM_DOMAIN_RENDER, I915_GEM_DOMAIN_RENDER,
-                   ffs(prog_data->total_scratch) - 11);
+                   prog_data->total_scratch / 1024 - 1);
       }
    } else {
       OUT_BATCH(0);
-- 
2.8.3