linux-kernel - [PATCH 1/6] drm: renesas: rz-du: rzg2l_du_encoder: convert to of_drm_find_and_get

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Message-Id: <20260116-drm-bridge-alloc-getput-drm_of_find_bridge-4-v1-1-e34b38f50d27@bootlin.com>
Date: Fri, 16 Jan 2026 18:32:36 +0100
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: Biju Das <biju.das.jz@...renesas.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>, 
 Anitha Chrisanthus <anitha.chrisanthus@...el.com>, 
 Edmund Dea <edmund.j.dea@...el.com>, Linus Walleij <linusw@...nel.org>, 
 Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>, 
 Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>, 
 Kieran Bingham <kieran.bingham+renesas@...asonboard.com>, 
 Geert Uytterhoeven <geert+renesas@...der.be>, 
 Magnus Damm <magnus.damm@...il.com>, 
 Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Cc: Hui Pu <Hui.Pu@...ealthcare.com>, Ian Ray <ian.ray@...ealthcare.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 dri-devel@...ts.freedesktop.org, linux-renesas-soc@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH 1/6] drm: renesas: rz-du: rzg2l_du_encoder: convert to
 of_drm_find_and_get_bridge()

of_drm_find_bridge() is deprecated. Move to its replacement
of_drm_find_and_get_bridge() which gets a bridge reference, and ensure it
is put when done.

This is made somewhat simpler by the fact that 'bridge' is a local
variable.

However we need to handle both branches of the main if().

In the 'else' case, just switch to of_drm_find_and_get_bridge() to ensure
the bridge is not freed while in use in the function tail
(drm_bridge_attach() mainly).

In the 'then' case, devm_drm_panel_bridge_add_typed() already increments
the refcount using devres which ties the bridge allocation lifetime to the
device lifetime, so we would not need to do anything. However to have the
same behaviour in both branches take an additional reference here, so that
the bridge needs to be put whichever branch is taken without more
complicated logic. Ensure to clear the bridge pointer however, to avoid
calling drm_bridge_put() on an ERR_PTR.

Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
---
 drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c
index 5e6dd16705e6..9b65bcefdb86 100644
--- a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c
+++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c
@@ -67,7 +67,7 @@ int rzg2l_du_encoder_init(struct rzg2l_du_device  *rcdu,
 {
 	struct rzg2l_du_encoder *renc;
 	struct drm_connector *connector;
-	struct drm_bridge *bridge;
+	struct drm_bridge *bridge __free(drm_bridge_put) = NULL;
 	int ret;
 
 	/*
@@ -83,10 +83,16 @@ int rzg2l_du_encoder_init(struct rzg2l_du_device  *rcdu,
 
 		bridge = devm_drm_panel_bridge_add_typed(rcdu->dev, panel,
 							 DRM_MODE_CONNECTOR_DPI);
-		if (IS_ERR(bridge))
-			return PTR_ERR(bridge);
+		if (IS_ERR(bridge)) {
+			// Inhibit the cleanup action on an ERR_PTR
+			ret = PTR_ERR(bridge);
+			bridge = NULL;
+			return ret;
+		}
+
+		drm_bridge_get(bridge);
 	} else {
-		bridge = of_drm_find_bridge(enc_node);
+		bridge = of_drm_find_and_get_bridge(enc_node);
 		if (!bridge)
 			return -EPROBE_DEFER;
 	}

-- 
2.52.0