linux-kernel - [PATCH 0/2] drm/mediatek: HDMI DDC v2 driver fixes

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Message-Id: <20251205-mtk-hdmi-ddc-v2-fixes-v1-0-260dd0d320f4@collabora.com>
Date: Fri, 05 Dec 2025 15:22:25 +0100
From: Louis-Alexis Eyraud <louisalexis.eyraud@...labora.com>
To: Chun-Kuang Hu <chunkuang.hu@...nel.org>, 
 Philipp Zabel <p.zabel@...gutronix.de>, David Airlie <airlied@...il.com>, 
 Simona Vetter <simona@...ll.ch>, Matthias Brugger <matthias.bgg@...il.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 CK Hu <ck.hu@...iatek.com>
Cc: kernel@...labora.com, dri-devel@...ts.freedesktop.org, 
 linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, 
 Louis-Alexis Eyraud <louisalexis.eyraud@...labora.com>
Subject: [PATCH 0/2] drm/mediatek: HDMI DDC v2 driver fixes

This patch series fixes two issues in the Mediatek HDMI DDC v2
driver (mtk_hdmi_ddc_v2).

Patch 1 fixes a potential issue on transfer timeout cases to properly
abort read/write transfers.
Patch 2 fixes DDC communication errors that occur when getting
or modifying display features with ddcutil with subcommands such as
detect, getvcp or setvcp:
```
$ ddcutil getvcp 10 -b 4 # read brightness
DDC communication failed for monitor on bus /dev/i2c-4

$ ddcutil setvcp 10 75 -b 4 # change brightness
DDC communication failed for monitor on bus /dev/i2c-4
```

These patches were tested on Mediatek Genio 510-EVK and 1200-EVK boards
with a kernel based on next-20251205 tag plus devicetree patches to
enable HDMI output.

Signed-off-by: Louis-Alexis Eyraud <louisalexis.eyraud@...labora.com>
---
Louis-Alexis Eyraud (2):
      drm/mediatek: mtk_hdmi_ddc_v2: Add transfer abort on timeout cases
      drm/mediatek: mtk_hdmi_ddc_v2: Fix multi-byte writes

 drivers/gpu/drm/mediatek/mtk_hdmi_ddc_v2.c | 58 +++++++++++++++++-------------
 1 file changed, 33 insertions(+), 25 deletions(-)
---
base-commit: 4e5a9b630580faea139e9837b4fba666db6bd728
change-id: 20251204-mtk-hdmi-ddc-v2-fixes-b5d61fdea639

Best regards,
-- 
Louis-Alexis Eyraud <louisalexis.eyraud@...labora.com>