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 (file)
--- 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 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2077,8 +2077,10 @@ static int ironlake_update_plane(struct drm_crtc *crtc,
        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 @@ static void ivb_update_cursor(struct drm_crtc *crtc, u32 base)
                        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 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4960,8 +4960,6 @@ static void haswell_init_clock_gating(struct drm_device *dev)
                        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 (file)
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -260,8 +260,11 @@ ivb_update_plane(struct drm_plane *plane, struct drm_crtc *crtc,
        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))