linux-kernel - [PATCH v2] drm/bridge-connector: Prioritize supported_formats over ycbcr_420

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Message-Id: <20241206-bridge-conn-fmt-prio-v2-1-85c817529b88@collabora.com>
Date: Fri, 06 Dec 2024 22:00:46 +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 v2] drm/bridge-connector: Prioritize supported_formats over
 ycbcr_420_allowed

Bridges having the DRM_BRIDGE_OP_HDMI flag set in drm_bridge->ops are
supposed to rely on drm_bridge->supported_formats bitmask to advertise
the supported colorspaces, including HDMI_COLORSPACE_YUV420.  Therefore,
the newly introduced drm_bridge->ycbcr_420_allowed flag becomes
redundant in this particular context.

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

Handle the inconsistency by ignoring ycbcr_420_allowed for HDMI bridges
and, instead, make use of the supported_formats bitmask when setting up
the bridge connector.

Additionally, ensure the YUV420 related bit is removed from the bitmask
passed to drmm_connector_hdmi_init() when the final ycbcr_420_allowed
flag for the connector ends up not being set (i.e. the case of having at
least one non-HDMI bridge in the pipeline that didn't enable it).

Fixes: 3ced1c687512 ("drm/display: bridge_connector: handle ycbcr_420_allowed")
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@...labora.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
---
 drivers/gpu/drm/display/drm_bridge_connector.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c b/drivers/gpu/drm/display/drm_bridge_connector.c
index 320c297008aaa8b6ef5b1f4c71928849b202e8ac..1f05278b8683a25a845f943720c76faeed24c2e2 100644
--- a/drivers/gpu/drm/display/drm_bridge_connector.c
+++ b/drivers/gpu/drm/display/drm_bridge_connector.c
@@ -414,7 +414,7 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 	drm_for_each_bridge_in_chain(encoder, bridge) {
 		if (!bridge->interlace_allowed)
 			connector->interlace_allowed = false;
-		if (!bridge->ycbcr_420_allowed)
+		if (!bridge->ycbcr_420_allowed && !(bridge->ops & DRM_BRIDGE_OP_HDMI))
 			connector->ycbcr_420_allowed = false;
 
 		if (bridge->ops & DRM_BRIDGE_OP_EDID)
@@ -436,6 +436,10 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 
 			if (bridge->supported_formats)
 				supported_formats = bridge->supported_formats;
+
+			if (!(bridge->supported_formats & BIT(HDMI_COLORSPACE_YUV420)))
+				connector->ycbcr_420_allowed = false;
+
 			if (bridge->max_bpc)
 				max_bpc = bridge->max_bpc;
 		}
@@ -459,7 +463,10 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 	if (connector_type == DRM_MODE_CONNECTOR_Unknown)
 		return ERR_PTR(-EINVAL);
 
-	if (bridge_connector->bridge_hdmi)
+	if (bridge_connector->bridge_hdmi) {
+		if (!connector->ycbcr_420_allowed)
+			supported_formats &= ~BIT(HDMI_COLORSPACE_YUV420);
+
 		ret = drmm_connector_hdmi_init(drm, connector,
 					       bridge_connector->bridge_hdmi->vendor,
 					       bridge_connector->bridge_hdmi->product,
@@ -468,10 +475,11 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 					       connector_type, ddc,
 					       supported_formats,
 					       max_bpc);
-	else
+	} else {
 		ret = drmm_connector_init(drm, connector,
 					  &drm_bridge_connector_funcs,
 					  connector_type, ddc);
+	}
 	if (ret)
 		return ERR_PTR(ret);
 

---
base-commit: f486c8aa16b8172f63bddc70116a0c897a7f3f02
change-id: 20241130-bridge-conn-fmt-prio-c517c1407ed5