4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
commit 06998a756a3865817b87a129a7e5d5bb66dc1ec3 upstream.
Similar to commit e10aec652f31 ("drm/edid: Add 6 bpc quirk for display
AEO model 0."), the EDID reports "DFP 1.x compliant TMDS" but it support
6bpc instead of 8 bpc.
Hence, use 6 bpc quirk for this panel.
Fixes: 196f954e2509 ("drm/i915/dp: Revert "drm/i915/dp: fall back to 18 bpp when sink capability is unknown"")
BugLink: https://bugs.launchpad.net/bugs/1749420
Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
Reviewed-by: Mario Kleiner <mario.kleiner.de@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v4.8+
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20180218085359.7817-1-kai.heng.feng@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/drm_edid.c | 3 +++
1 file changed, 3 insertions(+)
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -107,6 +107,9 @@ static const struct edid_quirk {
/* AEO model 0 reports 8 bpc, but is a 6 bpc panel */
{ "AEO", 0, EDID_QUIRK_FORCE_6BPC },
+ /* CPT panel of Asus UX303LA reports 8 bpc, but is a 6 bpc panel */
+ { "CPT", 0x17df, EDID_QUIRK_FORCE_6BPC },
+
/* Belinea 10 15 55 */
{ "MAX", 1516, EDID_QUIRK_PREFER_LARGE_60 },
{ "MAX", 0x77e, EDID_QUIRK_PREFER_LARGE_60 },