drm/i915: [GEN7] Use HW scheduler for fixed function shaders

This originally started as a patch from Bernard as a way of simply
setting the VS scheduler. After submitting the RFC patch, we decided to
also modify the DS scheduler. To be most explicit, I've made the patch
explicitly set all scheduler modes, and included the defines for other
modes (in case someone feels frisky later).

The rest of the story gets a bit weird. The first version of the patch
showed an almost unbelievable performance improvement. Since rebasing my
branch it appears the performance improvement has gone, unfortunately.
But setting these bits seem to be the right thing to do given that the
docs describe corruption that can occur with the default settings.

In summary, I am seeing no more perf improvements (or regressions) in my
limited testing, but we believe this should be set to prevent rendering
corruption, therefore cc stable.

v1: Clear bit 4 also (Ken + Eugeni)
Do a full clear + set of the bits we want (Me).

Cc: Bernard Kilarski <bernard.r.kilarski@intel.com>
Cc: stable <stable@vger.kernel.org>
Reviewed-by (RFC): Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Ben Widawsky <benjamin.widawsky@intel.com>
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 78179e03a901..96fc4679d438 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -8937,6 +8937,18 @@ static void gen6_init_clock_gating(struct drm_device *dev)
         }
 }
 
+static void gen7_setup_fixed_func_scheduler(struct drm_i915_private *dev_priv)
+{
+        uint32_t reg = I915_READ(GEN7_FF_THREAD_MODE);
+
+        reg &= ~GEN7_FF_SCHED_MASK;
+        reg |= GEN7_FF_TS_SCHED_HW;
+        reg |= GEN7_FF_VS_SCHED_HW;
+        reg |= GEN7_FF_DS_SCHED_HW;
+
+        I915_WRITE(GEN7_FF_THREAD_MODE, reg);
+}
+
 static void ivybridge_init_clock_gating(struct drm_device *dev)
 {
         struct drm_i915_private *dev_priv = dev->dev_private;
@@ -8981,6 +8993,8 @@ static void ivybridge_init_clock_gating(struct drm_device *dev)
                            DISPPLANE_TRICKLE_FEED_DISABLE);
                 intel_flush_display_plane(dev_priv, pipe);
         }
+
+        gen7_setup_fixed_func_scheduler(dev_priv);
 }
 
 static void valleyview_init_clock_gating(struct drm_device *dev)