linux-kernel - [PATCH v8 3/5] drm/bridge: deprecate old-style bridge allocation

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Message-Id: <20250320-drm-bridge-refcount-v8-3-b3ddaa9f1368@bootlin.com>
Date: Thu, 20 Mar 2025 16:42:12 +0100
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>, 
 Marek Vasut <marex@...x.de>, Stefan Agner <stefan@...er.ch>, 
 Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>, Inki Dae <inki.dae@...sung.com>, 
 Jagan Teki <jagan@...rulasolutions.com>, 
 Marek Szyprowski <m.szyprowski@...sung.com>
Cc: Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 Anusha Srivatsa <asrivats@...hat.com>, 
 Paul Kocialkowski <paulk@...-base.io>, Dmitry Baryshkov <lumag@...nel.org>, 
 Hervé Codina <herve.codina@...tlin.com>, 
 Hui Pu <Hui.Pu@...ealthcare.com>, dri-devel@...ts.freedesktop.org, 
 linux-kernel@...r.kernel.org, imx@...ts.linux.dev, 
 linux-arm-kernel@...ts.infradead.org, 
 Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH v8 3/5] drm/bridge: deprecate old-style bridge allocation

All DRM bridges are now supposed to be allocated using
devm_drm_bridge_alloc(), which is cleaner and necessary to support
refcounting.

Deprecate old school allocation using kzalloc and derivatives. In the
absence of a drm_bridge_init() or such initialization function, document
the deprecation on the first DRM bridge core function that is called after
allocation, i.e. drm_bridge_add().

Suggested-by: Maxime Ripard <mripard@...nel.org>
Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>

---

This patch was added in v8.
---
 drivers/gpu/drm/drm_bridge.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 2f2ecb73308e601b1a53ec8e7110933cef59b5da..17659b1cbdeae04e10b76f2aabc8ebba65c4f6e1 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -295,6 +295,10 @@ EXPORT_SYMBOL(__devm_drm_bridge_alloc);
  * drm_bridge_add - add the given bridge to the global bridge list
  *
  * @bridge: bridge control structure
+ *
+ * The bridge to be added must have been allocated by
+ * devm_drm_bridge_alloc(). Old-style allocation by kzalloc(),
+ * devm_kzalloc() and similar is deprecated.
  */
 void drm_bridge_add(struct drm_bridge *bridge)
 {

-- 
2.48.1