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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Mario Kleiner <mario.kleiner.de@gmail.com>,
	Alex Deucher <alexander.deucher@amd.com>,
	Sasha Levin <sashal@kernel.org>,
	amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: [PATCH AUTOSEL 5.5 09/28] drm/amd/display: Add link_rate quirk for Apple 15" MBP 2017
Date: Thu, 26 Mar 2020 19:23:38 -0400
Message-ID: <20200326232357.7516-9-sashal@kernel.org> (raw)
In-Reply-To: <20200326232357.7516-1-sashal@kernel.org>

From: Mario Kleiner <mario.kleiner.de@gmail.com>

[ Upstream commit dec9de2ada523b344eb2428abfedf9d6cd0a0029 ]

This fixes a problem found on the MacBookPro 2017 Retina panel:

The panel reports 10 bpc color depth in its EDID, and the
firmware chooses link settings at boot which support enough
bandwidth for 10 bpc (324000 kbit/sec aka LINK_RATE_RBR2
aka 0xc), but the DP_MAX_LINK_RATE dpcd register only reports
2.7 Gbps (multiplier value 0xa) as possible, in direct
contradiction of what the firmware successfully set up.

This restricts the panel to 8 bpc, not providing the full
color depth of the panel on Linux <= 5.5. Additionally, commit
'4a8ca46bae8a ("drm/amd/display: Default max bpc to 16 for eDP")'
introduced into Linux 5.6-rc1 will unclamp panel depth to
its full 10 bpc, thereby requiring a eDP bandwidth for all
modes that exceeds the bandwidth available and causes all modes
to fail validation -> No modes for the laptop panel -> failure
to set any mode -> Panel goes dark.

This patch adds a quirk specific to the MBP 2017 15" Retina
panel to override reported max link rate to the correct maximum
of 0xc = LINK_RATE_RBR2 to fix the darkness and reduced display
precision.

Please apply for Linux 5.6+ to avoid regressing Apple MBP panel
support.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
index 504055fc70e89..6f2b3ec17e7f0 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -2909,6 +2909,17 @@ static bool retrieve_link_cap(struct dc_link *link)
 		sink_id.ieee_device_id,
 		sizeof(sink_id.ieee_device_id));
 
+	/* Quirk Apple MBP 2017 15" Retina panel: Wrong DP_MAX_LINK_RATE */
+	{
+		uint8_t str_mbp_2017[] = { 101, 68, 21, 101, 98, 97 };
+
+		if ((link->dpcd_caps.sink_dev_id == 0x0010fa) &&
+		    !memcmp(link->dpcd_caps.sink_dev_id_str, str_mbp_2017,
+			    sizeof(str_mbp_2017))) {
+			link->reported_link_cap.link_rate = 0x0c;
+		}
+	}
+
 	core_link_read_dpcd(
 		link,
 		DP_SINK_HW_REVISION_START,
-- 
2.20.1


  parent reply index

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-26 23:23 [PATCH AUTOSEL 5.5 01/28] thunderbolt: Fix error code in tb_port_is_width_supported() Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 02/28] drm/bridge: dw-hdmi: fix AVI frame colorimetry Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 03/28] nvme-rdma: Avoid double freeing of async event data Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 04/28] ALSA: hda/realtek: Fix pop noise on ALC225 Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 05/28] staging: wfx: fix warning about freeing in-use mutex during device unregister Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 06/28] kconfig: introduce m32-flag and m64-flag Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 07/28] int128: fix __uint128_t compiler test in Kconfig Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 08/28] drm/amdgpu: add fbdev suspend/resume on gpu reset Sasha Levin
2020-03-26 23:23 ` Sasha Levin [this message]
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 10/28] drm/bochs: downgrade pci_request_region failure from error to warning Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 11/28] initramfs: restore default compression behavior Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 12/28] staging: greybus: loopback_test: fix potential path truncation Sasha Levin
2020-03-27  6:28   ` Greg KH
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 13/28] staging: greybus: loopback_test: fix potential path truncations Sasha Levin
2020-03-27  6:28   ` Greg Kroah-Hartman
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 14/28] arm64: smp: fix smp_send_stop() behaviour Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 15/28] arm64: smp: fix crash_smp_send_stop() behaviour Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 16/28] modpost: Get proper section index by get_secindex() instead of st_shndx Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 17/28] drm/amdgpu: fix typo for vcn1 idle check Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 18/28] tools/power turbostat: Fix gcc build warnings Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 19/28] tools/power turbostat: Fix missing SYS_LPI counter on some Chromebooks Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 20/28] tools/power turbostat: Fix 32-bit capabilities warning Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 21/28] nvmet-tcp: set MSG_MORE only if we actually have more to send Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 22/28] btrfs: fix removal of raid[56|1c34} incompat flags after removing block group Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 23/28] kconfig: Add yes2modconfig and mod2yesconfig targets Sasha Levin
2020-03-26 23:41   ` Tetsuo Handa
2020-03-27  6:26   ` Greg KH
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 24/28] ALSA: pcm: oss: Avoid plugin buffer overflow Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 25/28] ALSA: line6: Fix endless MIDI read loop Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 26/28] ALSA: pcm: oss: Remove WARNING from snd_pcm_plug_alloc() checks Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 27/28] tty: fix compat TIOCGSERIAL leaking uninitialized memory Sasha Levin
2020-03-27  6:27   ` Greg KH
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 28/28] drm/lease: fix WARNING in idr_destroy Sasha Levin

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