drm/i915: implement WaDisablePSDDualDispatchEnable on IVB & VLV

Workaround for dual port PS dispatch on GT1.

v2: pull in register definition & offset handling
v3: use IVB GT1 macro to get the right regs (Ben)
v4: add for VLV too (Ben)
v5: don't read the reg, it's masked so we'll only enable the one extra bit (Chris)
v6: use a _GT2 suffix for the second reg (Chris)
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Antti Koskipää <antti.koskipaa@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.c

@@ -1134,6 +1134,7 @@ static bool IS_DISPLAYREG(u32 reg)
 
 	switch (reg) {
 	case GEN7_ROW_CHICKEN2:
+	case GEN7_HALF_SLICE_CHICKEN1:
 		return false;
 	default:
 		break;

drivers/gpu/drm/i915/i915_reg.h

@@ -4305,6 +4305,11 @@
 #define GEN7_L3LOG_BASE			0xB070
 #define GEN7_L3LOG_SIZE			0x80
 
+#define GEN7_HALF_SLICE_CHICKEN1	0xe100 /* IVB GT1 + VLV */
+#define GEN7_HALF_SLICE_CHICKEN1_GT2	0xf100
+#define   GEN7_MAX_PS_THREAD_DEP		(8<<12)
+#define   GEN7_PSD_SINGLE_PORT_DISPATCH_ENABLE	(1<<3)
+
 #define GEN7_ROW_CHICKEN2		0xe4f4
 #define GEN7_ROW_CHICKEN2_GT2		0xf4f4
 #define   DOP_CLOCK_GATING_DISABLE	(1<<0)

drivers/gpu/drm/i915/intel_pm.c

@@ -3592,6 +3592,14 @@ static void ivybridge_init_clock_gating(struct drm_device *dev)
 		   CHICKEN3_DGMG_REQ_OUT_FIX_DISABLE |
 		   CHICKEN3_DGMG_DONE_FIX_DISABLE);
 
+	/* WaDisablePSDDualDispatchEnable */
+	if (IS_IVB_GT1(dev))
+		I915_WRITE(GEN7_HALF_SLICE_CHICKEN1,
+			   _MASKED_BIT_ENABLE(GEN7_PSD_SINGLE_PORT_DISPATCH_ENABLE));
+	else
+		I915_WRITE(GEN7_HALF_SLICE_CHICKEN1_GT2,
+			   _MASKED_BIT_ENABLE(GEN7_PSD_SINGLE_PORT_DISPATCH_ENABLE));
+
 	/* Apply the WaDisableRHWOOptimizationForRenderHang workaround. */
 	I915_WRITE(GEN7_COMMON_SLICE_CHICKEN1,
 		   GEN7_CSC1_RHWO_OPT_DISABLE_IN_RCC);
@@ -3679,6 +3687,9 @@ static void valleyview_init_clock_gating(struct drm_device *dev)
 		   CHICKEN3_DGMG_REQ_OUT_FIX_DISABLE |
 		   CHICKEN3_DGMG_DONE_FIX_DISABLE);
 
+	I915_WRITE(GEN7_HALF_SLICE_CHICKEN1,
+		   _MASKED_BIT_ENABLE(GEN7_PSD_SINGLE_PORT_DISPATCH_ENABLE));
+
 	/* Apply the WaDisableRHWOOptimizationForRenderHang workaround. */
 	I915_WRITE(GEN7_COMMON_SLICE_CHICKEN1,
 		   GEN7_CSC1_RHWO_OPT_DISABLE_IN_RCC);