drm/i915: Add a partial instruction shootdown workaround on Broadwell.

I believe this will be necessary on production hardware.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
[danvet: Fix whitespace fail spotted by checkpatch. Also add missing
:bdw w/a tag that Ville spotted.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index e313035..d575baf 100644 (file)
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -5048,6 +5048,9 @@
 #define   GEN7_SINGLE_SUBSCAN_DISPATCH_ENABLE  (1<<10)
 #define   GEN7_PSD_SINGLE_PORT_DISPATCH_ENABLE (1<<3)
 
+#define GEN8_ROW_CHICKEN               0xe4f0
+#define   PARTIAL_INSTRUCTION_SHOOTDOWN_DISABLE        (1<<8)
+
 #define GEN7_ROW_CHICKEN2              0xe4f4
 #define GEN7_ROW_CHICKEN2_GT2          0xf4f4
 #define   DOP_CLOCK_GATING_DISABLE     (1<<0)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 2ded0f6..f21c9f3 100644 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4801,6 +4801,10 @@ static void gen8_init_clock_gating(struct drm_device *dev)
        /* FIXME(BDW): Check all the w/a, some might only apply to
         * pre-production hw. */
 
+       /* WaDisablePartialInstShootdown:bdw */
+       I915_WRITE(GEN8_ROW_CHICKEN,
+                  _MASKED_BIT_ENABLE(PARTIAL_INSTRUCTION_SHOOTDOWN_DISABLE));
+
        /*
         * This GEN8_CENTROID_PIXEL_OPT_DIS W/A is only needed for
         * pre-production hardware