[Mesa-dev] [PATCH v2] i965/blorp: Use 16 pixel dispatch on Gen7.

[Paul Berry]

Gen7 hardware requires us to enable at least one WM dispatch mode,
even if there is no program being dispatched to.  When this code was
only used for HiZ operations (which don't use a WM program), we used
32-pixel dispatch, because it didn't matter.  But blit programs are
compiled for 16-pixel dispatch.  So just enable 16-wide dispatch
unconditionally.

Reviewed-by: Chad Versace <chad.versace at linux.intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

v2: Enable 16-wide dispatch unconditionally rather than add the
unnecessary complication of using 32-wide dispatch when there is no WM
program.
---
 src/mesa/drivers/dri/i965/gen7_blorp.cpp |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/gen7_blorp.cpp b/src/mesa/drivers/dri/i965/gen7_blorp.cpp
index dee342f..a6185df 100644
--- a/src/mesa/drivers/dri/i965/gen7_blorp.cpp
+++ b/src/mesa/drivers/dri/i965/gen7_blorp.cpp
@@ -453,7 +453,15 @@ gen7_blorp_emit_ps_config(struct brw_context *brw,
 
    dw2 = dw4 = dw5 = 0;
    dw4 |= (brw->max_wm_threads - 1) << max_threads_shift;
-   dw4 |= GEN7_PS_32_DISPATCH_ENABLE;
+
+   /* If there's a WM program, we need to do 16-pixel dispatch since that's
+    * what the program is compiled for.  If there isn't, then it shouldn't
+    * matter because no program is actually being run.  However, the hardware
+    * gets angry if we don't enable at least one dispatch mode, so just enable
+    * 16-pixel dispatch unconditionally.
+    */
+   dw4 |= GEN7_PS_16_DISPATCH_ENABLE;
+
    if (intel->is_haswell)
       dw4 |= SET_FIELD(1, HSW_PS_SAMPLE_MASK); /* 1 sample for now */
    if (params->use_wm_prog) {
-- 
1.7.7.6