linux-kernel - [PATCH 1/2] drm/imx: parallel-display: convert to devm_drm_bridge

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Message-Id: <20251014-drm-bridge-alloc-imx-ipuv3-v1-1-a1bb1dcbff50@bootlin.com>
Date: Tue, 14 Oct 2025 13:30:51 +0200
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: Ernest Van Hoecke <ernestvanhoecke@...il.com>, 
 Philipp Zabel <p.zabel@...gutronix.de>, 
 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>, 
 Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>
Cc: Hui Pu <Hui.Pu@...ealthcare.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 dri-devel@...ts.freedesktop.org, imx@...ts.linux.dev, 
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH 1/2] drm/imx: parallel-display: convert to
 devm_drm_bridge_alloc() API

This is the new API for allocating DRM bridges.

This conversion was missed during the initial conversion of all bridges to
the new API. Thus all kernels with commit 94d50c1a2ca3 ("drm/bridge:
get/put the bridge reference in drm_bridge_attach/detach()") and using this
driver now warn due to drm_bridge_attach() incrementing the refcount, which
is not initialized without using devm_drm_bridge_alloc() for allocation.

To make the conversion simple and straightforward without messing up with
the drmm_simple_encoder_alloc(), move the struct drm_bridge from struct
imx_parallel_display_encoder to struct imx_parallel_display.

Also remove the 'struct imx_parallel_display *pd' from struct
imx_parallel_display_encoder, not needed anymore.

Fixes: 94d50c1a2ca3 ("drm/bridge: get/put the bridge reference in drm_bridge_attach/detach()")
Reported-by: Ernest Van Hoecke <ernestvanhoecke@...il.com>
Closes: https://lore.kernel.org/all/hlf4wdopapxnh4rekl5s3kvoi6egaga3lrjfbx6r223ar3txri@3ik53xw5idyh/
Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
---
 drivers/gpu/drm/imx/ipuv3/parallel-display.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/imx/ipuv3/parallel-display.c b/drivers/gpu/drm/imx/ipuv3/parallel-display.c
index 6d8325c766979aa3ba98970f00806e99c139d3c3..3d0de9c6e925978b7532b6d13caf6909cc343dd7 100644
--- a/drivers/gpu/drm/imx/ipuv3/parallel-display.c
+++ b/drivers/gpu/drm/imx/ipuv3/parallel-display.c
@@ -25,19 +25,18 @@
 
 struct imx_parallel_display_encoder {
 	struct drm_encoder encoder;
-	struct drm_bridge bridge;
-	struct imx_parallel_display *pd;
 };
 
 struct imx_parallel_display {
 	struct device *dev;
 	u32 bus_format;
 	struct drm_bridge *next_bridge;
+	struct drm_bridge bridge;
 };
 
 static inline struct imx_parallel_display *bridge_to_imxpd(struct drm_bridge *b)
 {
-	return container_of(b, struct imx_parallel_display_encoder, bridge)->pd;
+	return container_of(b, struct imx_parallel_display, bridge);
 }
 
 static const u32 imx_pd_bus_fmts[] = {
@@ -195,15 +194,13 @@ static int imx_pd_bind(struct device *dev, struct device *master, void *data)
 	if (IS_ERR(imxpd_encoder))
 		return PTR_ERR(imxpd_encoder);
 
-	imxpd_encoder->pd = imxpd;
 	encoder = &imxpd_encoder->encoder;
-	bridge = &imxpd_encoder->bridge;
+	bridge = &imxpd->bridge;
 
 	ret = imx_drm_encoder_parse_of(drm, encoder, imxpd->dev->of_node);
 	if (ret)
 		return ret;
 
-	bridge->funcs = &imx_pd_bridge_funcs;
 	drm_bridge_attach(encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
 
 	connector = drm_bridge_connector_init(drm, encoder);
@@ -228,9 +225,10 @@ static int imx_pd_probe(struct platform_device *pdev)
 	u32 bus_format = 0;
 	const char *fmt;
 
-	imxpd = devm_kzalloc(dev, sizeof(*imxpd), GFP_KERNEL);
-	if (!imxpd)
-		return -ENOMEM;
+	imxpd = devm_drm_bridge_alloc(dev, struct imx_parallel_display, bridge,
+				      &imx_pd_bridge_funcs);
+	if (IS_ERR(imxpd))
+		return PTR_ERR(imxpd);
 
 	/* port@1 is the output port */
 	imxpd->next_bridge = devm_drm_of_get_bridge(dev, np, 1, 0);

-- 
2.51.0