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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        "Daniel Vetter" <daniel.vetter@ffwll.ch>,
        "Mario Kleiner" <mario.kleiner.de@gmail.com>,
        "Kai-Heng Feng" <kai.heng.feng@canonical.com>
Date:   Thu, 07 Jun 2018 15:05:21 +0100
Message-ID: <lsq.1528380321.825512326@decadent.org.uk>
Subject: [PATCH 3.16 264/410] drm/edid: Add 6 bpc quirk for CPT panel in
 Asus UX303LA
In-Reply-To: <lsq.1528380320.647747352@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
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3.16.57-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Kai-Heng Feng <kai.heng.feng@canonical.com>

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@canonical.com>
Reviewed-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180218085359.7817-1-kai.heng.feng@canonical.com
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 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
@@ -105,6 +105,9 @@ static 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 },