[Intel-gfx] [PATCH 08/28] drm/i915: Fix IVB GT2 WaDisableDopClockGating and WaDisablePSDDualDispatchEnable

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

IVB GT2 has two registers for these things, and both must be written.

To add a bit more confusion both Bspec and the W/A database state that
WaDisablePSDDualDispatchEnable is only needed for IVB GT1, but the W/A
database also says to write even the second GT2 only register. So I
don't really know what the right thing here is.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 6a1d98a..b268a55 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4828,9 +4828,13 @@ static void ivybridge_init_clock_gating(struct drm_device *dev)
 	if (IS_IVB_GT1(dev))
 		I915_WRITE(GEN7_HALF_SLICE_CHICKEN1,
 			   _MASKED_BIT_ENABLE(GEN7_PSD_SINGLE_PORT_DISPATCH_ENABLE));
-	else
+	else {
+		/* must write both registers */
+		I915_WRITE(GEN7_HALF_SLICE_CHICKEN1,
+			   _MASKED_BIT_ENABLE(GEN7_PSD_SINGLE_PORT_DISPATCH_ENABLE));
 		I915_WRITE(GEN7_HALF_SLICE_CHICKEN1_GT2,
 			   _MASKED_BIT_ENABLE(GEN7_PSD_SINGLE_PORT_DISPATCH_ENABLE));
+	}
 
 	/* Apply the WaDisableRHWOOptimizationForRenderHang:ivb workaround. */
 	I915_WRITE(GEN7_COMMON_SLICE_CHICKEN1,
@@ -4846,10 +4850,13 @@ static void ivybridge_init_clock_gating(struct drm_device *dev)
 	if (IS_IVB_GT1(dev))
 		I915_WRITE(GEN7_ROW_CHICKEN2,
 			   _MASKED_BIT_ENABLE(DOP_CLOCK_GATING_DISABLE));
-	else
+	else {
+		/* must write both registers */
+		I915_WRITE(GEN7_ROW_CHICKEN2,
+			   _MASKED_BIT_ENABLE(DOP_CLOCK_GATING_DISABLE));
 		I915_WRITE(GEN7_ROW_CHICKEN2_GT2,
 			   _MASKED_BIT_ENABLE(DOP_CLOCK_GATING_DISABLE));
-
+	}
 
 	/* WaForceL3Serialization:ivb */
 	I915_WRITE(GEN7_L3SQCREG4, I915_READ(GEN7_L3SQCREG4) &
-- 
1.8.3.2