From: Ville Syrjälä <[email protected]>

According to BSpec, trickle feed should be disabled for BW and
mobile CL. Those constraints seem to match all of our gen4 chipsets.

Trickle feed is disabled via the MI_ARB_STATE register instead of
per plane controls on gen4.

Reviewed-by: Chris Wilson <[email protected]>
Signed-off-by: Ville Syrjälä <[email protected]>
---
 drivers/gpu/drm/i915/intel_pm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 47f3c48..2948764 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4944,6 +4944,8 @@ static void crestline_init_clock_gating(struct drm_device 
*dev)
        I915_WRITE(DSPCLK_GATE_D, 0);
        I915_WRITE(RAMCLK_GATE_D, 0);
        I915_WRITE16(DEUC, 0);
+       I915_WRITE(MI_ARB_STATE,
+                  _MASKED_BIT_ENABLE(MI_ARB_DISPLAY_TRICKLE_FEED_DISABLE));
 }
 
 static void broadwater_init_clock_gating(struct drm_device *dev)
@@ -4956,6 +4958,8 @@ static void broadwater_init_clock_gating(struct 
drm_device *dev)
                   I965_ISC_CLOCK_GATE_DISABLE |
                   I965_FBC_CLOCK_GATE_DISABLE);
        I915_WRITE(RENCLK_GATE_D2, 0);
+       I915_WRITE(MI_ARB_STATE,
+                  _MASKED_BIT_ENABLE(MI_ARB_DISPLAY_TRICKLE_FEED_DISABLE));
 }
 
 static void gen3_init_clock_gating(struct drm_device *dev)
-- 
1.8.1.5

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