We cannot the initial configuration set by the BIOS not to have a dither
mode enabled which conflicts with our enabling the Spatial Temporal 1
dither mode for PCH. In particular, the BIOS may either enable temporal
dithering or the Spatial Temporal 2 with the result that we enable pure
temporal dithering. Temporal dithering looks bad and is perceived as a
flicker.
Fixes:
Bug 29248 - [Arrandale] Annoying flicker on internal panel, goes away
after suspend to RAM
https://bugs.freedesktop.org/show_bug.cgi?id=29248
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/intel_display.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_display.c
b/drivers/gpu/drm/i915/intel_display.c
index 7133436..fb6568b 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3925,6 +3925,7 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
if (dev_priv->lvds_dither) {
if (HAS_PCH_SPLIT(dev)) {
pipeconf |= PIPE_ENABLE_DITHER;
+ pipeconf &= ~PIPE_DITHER_TYPE_MASK;
pipeconf |= PIPE_DITHER_TYPE_ST01;
} else
lvds |= LVDS_ENABLE_DITHER;
--
1.7.1
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