Commit a392a103 authored Jul 25, 2010 by Chris Wilson Committed by Eric Anholt Jul 26, 2010

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 <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>

parent be9a3dbf

drivers/gpu/drm/i915/intel_display.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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;