linux-kernel - [PATCH 03/12] drm: of: try binding port parent node instead of the port itself

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Message-Id: <20250719-ums9230-drm-v1-3-e4344a05eb3d@abscue.de>
Date: Sat, 19 Jul 2025 14:09:39 +0200
From: Otto Pflüger <otto.pflueger@...cue.de>
To: David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Orson Zhai <orsonzhai@...il.com>, 
 Baolin Wang <baolin.wang@...ux.alibaba.com>, 
 Chunyan Zhang <zhang.lyra@...il.com>, Kevin Tang <kevin.tang@...soc.com>
Cc: dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, 
 Otto Pflüger <otto.pflueger@...cue.de>
Subject: [PATCH 03/12] drm: of: try binding port parent node instead of the
 port itself

The drm_of_component_probe function is intended to bind all devices in
an OF graph given a set of ports linked using the "ports" property on a
main device node. This means that it should also bind the components
providing these ports, not just the components of other ports connected
to them. In order to do this, it calls drm_of_component_match_add with
a pointer to each port node after checking that its parent node is a
device.

However, when given a pointer to the port node, the compare_of callback
does not match it with a device node and thus fails to detect that the
node belongs to a component. Fix this by passing a pointer to the parent
node here too.

Currently only the Unisoc platform driver relies on this feature, which
was previously broken and is fixed by this change. On other platforms,
the "ports" property points to ports that are not part of a component,
i.e. the components only have indirect connections to the main node.

Signed-off-by: Otto Pflüger <otto.pflueger@...cue.de>
---
 drivers/gpu/drm/drm_of.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index d0183dea770308e77f05da364ffe087d53f3be36..b972facc2ec3fe40a4e10b5d7178b5ac8c0158d5 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -132,7 +132,7 @@ int drm_of_component_probe(struct device *dev,

 		if (of_device_is_available(port->parent))
 			drm_of_component_match_add(dev, &match, compare_of,
-						   port);
+						   port->parent);

 		of_node_put(port);
 	}

-- 
2.50.0