The dithering introduced in
commit 3b5c78a35cf7511c15e09a9b0ffab290a42d9bcf
Author: Adam Jackson <ajax at redhat.com>
Date: Tue Dec 13 15:41:00 2011 -0800
drm/i915/dp: Dither down to 6bpc if it makes the mode fit
stores the INTEL_MODE_DP_FORCE_6BPC flag in the private_flags of the
adjusted mode, while intel_choose_pipe_bpp_dither() determining the color
depth was passed the original mode, without the flag, so it would never
have any effect. However, the BPC was clamped by VBT settings, making
things work by coincidence, until that part was removed in
commit 4344b813f105a19f793f1fd93ad775b784648b95
Author: Daniel Vetter <daniel.vetter at ffwll.ch>
Date: Fri Aug 10 11:10:20 2012 +0200
Pass adjusted_mode instead of mode to intel_choose_pipe_bpp_dither() to
make INTEL_MODE_DP_FORCE_6BPC have effect.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=47621
CC: stable at vger.kernel.org
Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
drivers/gpu/drm/i915/intel_display.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 08c3f69..0a9802a 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4936,7 +4936,8 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
intel_crtc_update_cursor(crtc, true);
/* determine panel color depth */
- dither = intel_choose_pipe_bpp_dither(crtc, fb, &intel_crtc->bpp, mode);
+ dither = intel_choose_pipe_bpp_dither(crtc, fb, &intel_crtc->bpp,
+ adjusted_mode);
if (is_lvds && dev_priv->lvds_dither)
dither = true;
--
1.7.9.5
