drm/i915: Disable trickle feed for gen2/3
My 830 is unhappy with trickle feed enabled. The symptom is that
the image on the screen shifts a bit to right occasionally.
The BIOS initially disables trickle feed, but it gets reset during
suspend, so we need to re-disable it ourselves. Juse disable it
always.
Also disable it for all other gen2/3 platforms since we disable it
for all more recent platforms as well (until HSW that is). At least
my 855 doesn't seem to mind us doing this. I don't have gen3
hardware to test that.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 38b61e4..8541feb 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6138,6 +6138,9 @@
/* On GEN3 we really need to make sure the ARB C3 LP bit is set */
I915_WRITE(MI_ARB_STATE, _MASKED_BIT_ENABLE(MI_ARB_C3_LP_WRITE_ENABLE));
+
+ I915_WRITE(MI_ARB_STATE,
+ _MASKED_BIT_ENABLE(MI_ARB_DISPLAY_TRICKLE_FEED_DISABLE));
}
static void i85x_init_clock_gating(struct drm_device *dev)
@@ -6149,6 +6152,9 @@
/* interrupts should cause a wake up from C3 */
I915_WRITE(MI_STATE, _MASKED_BIT_ENABLE(MI_AGPBUSY_INT_EN) |
_MASKED_BIT_DISABLE(MI_AGPBUSY_830_MODE));
+
+ I915_WRITE(MEM_MODE,
+ _MASKED_BIT_ENABLE(MEM_DISPLAY_TRICKLE_FEED_DISABLE));
}
static void i830_init_clock_gating(struct drm_device *dev)
@@ -6156,6 +6162,10 @@
struct drm_i915_private *dev_priv = dev->dev_private;
I915_WRITE(DSPCLK_GATE_D, OVRUNIT_CLOCK_GATE_DISABLE);
+
+ I915_WRITE(MEM_MODE,
+ _MASKED_BIT_ENABLE(MEM_DISPLAY_A_TRICKLE_FEED_DISABLE) |
+ _MASKED_BIT_ENABLE(MEM_DISPLAY_B_TRICKLE_FEED_DISABLE));
}
void intel_init_clock_gating(struct drm_device *dev)