From a392a10367508930607a17ab60b4148f86adf2bc Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Sun, 25 Jul 2010 23:09:13 +0100 Subject: [PATCH] drm/i915: Clear any existing dither mode prior to enabling spatial dithering 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 Signed-off-by: Eric Anholt --- drivers/gpu/drm/i915/intel_display.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index ab8162afb4a7..445fdafc131f 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -3736,6 +3736,7 @@ 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;