linux-kernel - [PATCH 8/9] drm/bridge: add drm_for_each_bridge_in_chain

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Message-Id: <20250723-drm-bridge-alloc-getput-for_each_bridge-v1-8-be8f4ae006e9@bootlin.com>
Date: Wed, 23 Jul 2025 11:54:15 +0200
From: Luca Ceresoli <luca.ceresoli@...tlin.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>, 
 Miguel Ojeda <ojeda@...nel.org>, Nathan Chancellor <nathan@...nel.org>, 
 Nick Desaulniers <nick.desaulniers+lkml@...il.com>, 
 Bill Wendling <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>, 
 Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Cc: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>, 
 Chaoyi Chen <chaoyi.chen@...k-chips.com>, Hui Pu <Hui.Pu@...ealthcare.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 llvm@...ts.linux.dev, Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH 8/9] drm/bridge: add drm_for_each_bridge_in_chain_from()

Add variant of drm_for_each_bridge_in_chain_scoped() that iterates on the
encoder bridge from a given bridge until the end of the chain.

Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
---
 include/drm/drm_bridge.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 0a45ed862ca3293bd0b12dacf3ba2c5429800d00..b271e1204c002f8dba080448583d75612f22a366 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -1389,6 +1389,25 @@ drm_bridge_get_next_bridge_and_put(struct drm_bridge *bridge)
 	     bridge;							\
 	     bridge = drm_bridge_get_next_bridge_and_put(bridge))
 
+/**
+ * drm_for_each_bridge_in_chain_from - iterate over all bridges starting
+ *                                     from the given bridge
+ * @first_bridge: the bridge to start from
+ * @bridge: a bridge pointer updated to point to the current bridge at each
+ *	    iteration
+ *
+ * Iterate over all bridges in the encoder chain starting from
+ * @first_bridge, included.
+ *
+ * Automatically gets/puts the bridge reference while iterating, and puts
+ * the reference even if returning or breaking in the middle of the loop.
+ */
+#define drm_for_each_bridge_in_chain_from(first_bridge, bridge)		\
+	for (struct drm_bridge *bridge __free(drm_bridge_put) =		\
+		     drm_bridge_get(first_bridge);			\
+	     bridge;							\
+	     bridge = drm_bridge_get_next_bridge_and_put(bridge))
+
 enum drm_mode_status
 drm_bridge_chain_mode_valid(struct drm_bridge *bridge,
 			    const struct drm_display_info *info,

-- 
2.50.1