drm/i915: enable trickle feed on Haswell

We shouldn't disable the trickle feed bits on Haswell. Our
documentation explicitly says the trickle feed bits of PRI_CTL and
CUR_CTL should not be programmed to 1, and the hardware engineer also
asked us to not program the SPR_CTL field to 1. Leaving the bits as 1
could cause underflows.

Reported-by: Arthur Runyan <arthur.j.runyan@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
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 dcc58ea..c159e1a 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3313,6 +3313,7 @@
 #define   MCURSOR_PIPE_A	0x00
 #define   MCURSOR_PIPE_B	(1 << 28)
 #define   MCURSOR_GAMMA_ENABLE  (1 << 26)
+#define   CURSOR_TRICKLE_FEED_DISABLE	(1 << 14)
 #define _CURABASE		(dev_priv->info->display_mmio_offset + 0x70084)
 #define _CURAPOS		(dev_priv->info->display_mmio_offset + 0x70088)
 #define   CURSOR_POS_MASK       0x007FF
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index a98392f..a1e502b 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2077,8 +2077,10 @@
 	else
 		dspcntr &= ~DISPPLANE_TILED;
 
-	/* must disable */
-	dspcntr |= DISPPLANE_TRICKLE_FEED_DISABLE;
+	if (IS_HASWELL(dev))
+		dspcntr &= ~DISPPLANE_TRICKLE_FEED_DISABLE;
+	else
+		dspcntr |= DISPPLANE_TRICKLE_FEED_DISABLE;
 
 	I915_WRITE(reg, dspcntr);
 
@@ -6762,8 +6764,10 @@
 			cntl &= ~(CURSOR_MODE | MCURSOR_GAMMA_ENABLE);
 			cntl |= CURSOR_MODE_DISABLE;
 		}
-		if (IS_HASWELL(dev))
+		if (IS_HASWELL(dev)) {
 			cntl |= CURSOR_PIPE_CSC_ENABLE;
+			cntl &= ~CURSOR_TRICKLE_FEED_DISABLE;
+		}
 		I915_WRITE(CURCNTR_IVB(pipe), cntl);
 
 		intel_crtc->cursor_visible = visible;
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 6b1d003..0c115cc 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4960,8 +4960,6 @@
 			I915_READ(GEN7_SQ_CHICKEN_MBCUNIT_CONFIG) |
 			GEN7_SQ_CHICKEN_MBCUNIT_SQINTMOB);
 
-	g4x_disable_trickle_feed(dev);
-
 	/* WaVSRefCountFullforceMissDisable:hsw */
 	gen7_setup_fixed_func_scheduler(dev_priv);
 
diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
index 78b621c..ad6ec4b 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -260,8 +260,11 @@
 	if (obj->tiling_mode != I915_TILING_NONE)
 		sprctl |= SPRITE_TILED;
 
-	/* must disable */
-	sprctl |= SPRITE_TRICKLE_FEED_DISABLE;
+	if (IS_HASWELL(dev))
+		sprctl &= ~SPRITE_TRICKLE_FEED_DISABLE;
+	else
+		sprctl |= SPRITE_TRICKLE_FEED_DISABLE;
+
 	sprctl |= SPRITE_ENABLE;
 
 	if (IS_HASWELL(dev))