linux-kernel - [PATCH v3 0/2] Fix ycbcr_420_allowed inconsistency for HDMI bridges

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Message-Id: <20241217-bridge-conn-fmt-prio-v3-0-3ecb3c8fc06f@collabora.com>
Date: Tue, 17 Dec 2024 00:54:06 +0200
From: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
To: Andrzej Hajda <andrzej.hajda@...el.com>, 
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: kernel@...labora.com, dri-devel@...ts.freedesktop.org, 
 linux-kernel@...r.kernel.org
Subject: [PATCH v3 0/2] Fix ycbcr_420_allowed inconsistency for HDMI
 bridges

Bridges with DRM_BRIDGE_OP_HDMI set in drm_bridge->ops are expected to
rely on drm_bridge->supported_formats to advertise the supported
colorspaces, including HDMI_COLORSPACE_YUV420.

However, when drm_bridge_connector gets initialised, only
drm_bridge->ycbcr_420_allowed is considered in the process of adjusting
the drm_connector->ycbcr_420_allowed, which effectively discards the
formats advertised by the HDMI bridge.

This patchset tries to address the issue by prioritizing
supported_formats over ycbcr_420_allowed.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
---
Changes in v3:
- Simplified the inconsistency handling by overwriting ycbcr_420_allowed
  for HDMI bridges before adding them to the global bridge list
- Added a 2nd patch to check if supported_formats matches
  ycbcr_420_allowed on HDMI connector initialization (Dmitry)
- Link to v2: https://lore.kernel.org/r/20241206-bridge-conn-fmt-prio-v2-1-85c817529b88@collabora.com

Changes in v2:
- Wrapped HDMI_COLORSPACE_YUV420 flag in the BIT() macro to properly
  check its presence in supported_formats
- Ensured YUV420 gets removed from the bitmask passed to
  drmm_connector_hdmi_init() when ycbcr_420_allowed is not set
- Link to v1: https://lore.kernel.org/r/20241130-bridge-conn-fmt-prio-v1-1-146b663f17f3@collabora.com

---
Cristian Ciocaltea (2):
      drm/bridge-connector: Prioritize supported_formats over ycbcr_420_allowed
      drm/connector: hdmi: Validate supported_formats matches ycbcr_420_allowed

 drivers/gpu/drm/display/drm_bridge_connector.c | 8 ++++++--
 drivers/gpu/drm/drm_bridge.c                   | 4 ++++
 drivers/gpu/drm/drm_connector.c                | 3 +++
 3 files changed, 13 insertions(+), 2 deletions(-)
---
base-commit: f486c8aa16b8172f63bddc70116a0c897a7f3f02
change-id: 20241130-bridge-conn-fmt-prio-c517c1407ed5