[ 22/95] drm/i915: ignore eDP bpc settings from vbt

From: Ben Hutchings
Date: Sun Sep 09 2012 - 19:20:20 EST

3.2-stable review patch. If anyone has any objections, please let me know.


From: Daniel Vetter <daniel.vetter@xxxxxxxx>

commit 4344b813f105a19f793f1fd93ad775b784648b95 upstream.

This has originally been introduced to not oversubscribe the dp links

commit 885a5fb5b120a5c7e0b3baad7b0feb5a89f76c18
Author: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx>
Date: Tue Jan 12 05:38:31 2010 +0800

drm/i915: fix pixel color depth setting on eDP

Since then we've fixed up the dp link bandwidth calculation code and
should now automatically fall back to 6bpc dithering. So this is

Furthermore it seems to break the new MacbookPro with retina display,
hence let's just rip this out.

Reported-by: Benoit Gschwind <gschwind@xxxxxxxxxxx>
Cc: Benoit Gschwind <gschwind@xxxxxxxxxxx>
Cc: Francois Rigaut <frigaut@xxxxxxxxx>
Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
Tested-by: Benoit Gschwind <gschwind@xxxxxxxxxxx>
Tested-by: Bernhard Froemel <froemel at vmars tuwien.ac.at>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>


Testing feedback highgly welcome, and thanks for Benoit for finding
out that the bpc computations are busted.
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
drivers/gpu/drm/i915/intel_display.c | 11 -----------
1 file changed, 11 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 88913a4..a69a3d0 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3754,17 +3754,6 @@ static bool intel_choose_pipe_bpp_dither(struct drm_crtc *crtc,

- if (intel_encoder->type == INTEL_OUTPUT_EDP) {
- /* Use VBT settings if we have an eDP panel */
- unsigned int edp_bpc = dev_priv->edp.bpp / 3;
- if (edp_bpc < display_bpc) {
- DRM_DEBUG_KMS("clamping display bpc (was %d) to eDP (%d)\n", display_bpc, edp_bpc);
- display_bpc = edp_bpc;
- }
- continue;
- }
/* Not one of the known troublemakers, check the EDID */
list_for_each_entry(connector, &dev->mode_config.connector_list,
head) {

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