linux-kernel - [PATCH v2 0/2] drm/msm/dp: Fix Type-C Timing

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Message-Id: <20250212-sdm845_dp-v2-0-4954e51458f4@gmail.com>
Date: Wed, 12 Feb 2025 15:03:45 -0800
From: "James A. MacInnes" <james.a.macinnes@...il.com>
To: Rob Clark <robdclark@...il.com>, 
 Abhinav Kumar <quic_abhinavk@...cinc.com>, 
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, Sean Paul <sean@...rly.run>, 
 Marijn Suijten <marijn.suijten@...ainline.org>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Chandan Uddaraju <chandanu@...eaurora.org>, 
 Stephen Boyd <swboyd@...omium.org>, Vara Reddy <quic_varar@...cinc.com>, 
 Tanmay Shah <tanmay@...eaurora.org>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
 freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Guenter Roeck <groeck@...omium.org>, Rob Clark <robdclark@...omium.org>, 
 "James A. MacInnes" <james.a.macinnes@...il.com>
Subject: [PATCH v2 0/2] drm/msm/dp: Fix Type-C Timing

SDM845 Type-C DisplayPort output inactive on DP Monitor and tears on HDMI.

During testing and research found that the dp and dpu drivers more
closely match later incarnations of the Android driver.
Compared against the 4.9 Android and found the porch timing and
wide bus elements were disabled.
Tested by commenting out code and the graphical glitches on
HDMI improved.
Fully turning off wide_bus resolved the single vertical line and
vblank errors when using non-native resolutions.
Removing the porch adjustment fixed HDMI and DisplayPort operated
correctly (for the first time) for all monitor supported resolutions.

Changes v1:
- Patch 1/2: Separated the descriptor from the sc7180 and turned off
             wide_bus support.
- Patch 2/2: Removed porch timing adjustment.

Changes v2:
- Patch 1/2: Removed unneeded assignment.
             Increased verbosity of commit message.
- Patch 2/2: Added comments to explain use of wide_bus_en.
             Increased verbosity of commit message.

Verified functionality on SDM845 using Lantronix SOM.
Tested with Type-C to DisplayPort and Dell Monitor.
Tested with Type-C hub with HDMI to Samsung 4k TV.

James A. MacInnes (2):
  drm/msm/dp: Disable wide bus support for SDM845
  drm/msm/disp: Correct porch timing for SDM845

 drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c | 8 ++++----
 drivers/gpu/drm/msm/dp/dp_display.c                  | 7 ++++++-
 2 files changed, 10 insertions(+), 5 deletions(-)

--
2.43.0

---
James A. MacInnes (2):
      drm/msm/dp: Disable wide bus support for SDM845
      drm/msm/disp: Correct porch timing for SDM845

 drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c | 14 +++++++++-----
 drivers/gpu/drm/msm/dp/dp_display.c                  |  7 ++++++-
 2 files changed, 15 insertions(+), 6 deletions(-)
---
base-commit: ffd294d346d185b70e28b1a28abe367bbfe53c04
change-id: 20250212-sdm845_dp-6ed993977a53

Best regards,
-- 
James A. MacInnes <james.a.macinnes@...il.com>