linux-kernel - [PATCH v3 18/22] drm/bridge: imx8qxp-pixel-combiner: convert to devm_drm_bridge

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Message-Id: <20250509-drm-bridge-convert-to-alloc-api-v3-18-b8bc1f16d7aa@bootlin.com>
Date: Fri, 09 May 2025 15:53:44 +0200
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: 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>, 
 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>, 
 Jagan Teki <jagan@...rulasolutions.com>, Shawn Guo <shawnguo@...nel.org>, 
 Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>, 
 Douglas Anderson <dianders@...omium.org>, 
 Chun-Kuang Hu <chunkuang.hu@...nel.org>, 
 Krzysztof Kozlowski <krzk@...nel.org>
Cc: Anusha Srivatsa <asrivats@...hat.com>, 
 Paul Kocialkowski <paulk@...-base.io>, Dmitry Baryshkov <lumag@...nel.org>, 
 Hui Pu <Hui.Pu@...ealthcare.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 dri-devel@...ts.freedesktop.org, asahi@...ts.linux.dev, 
 linux-kernel@...r.kernel.org, chrome-platform@...ts.linux.dev, 
 imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
 linux-mediatek@...ts.infradead.org, linux-amlogic@...ts.infradead.org, 
 linux-renesas-soc@...r.kernel.org, platform-driver-x86@...r.kernel.org, 
 linux-samsung-soc@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
 freedreno@...ts.freedesktop.org, linux-stm32@...md-mailman.stormreply.com, 
 Luca Ceresoli <luca.ceresoli@...tlin.com>, Liu Ying <victor.liu@....com>
Subject: [PATCH v3 18/22] drm/bridge: imx8qxp-pixel-combiner: convert to
 devm_drm_bridge_alloc() API

This is the new API for allocating DRM bridges.

This driver embeds an array of channels in the main struct, and each
channel embeds a drm_bridge. This prevents dynamic, refcount-based
deallocation of the bridges.

To make the new, dynamic bridge allocation possible:

 * change the array of channels into an array of channel pointers
 * allocate each channel using devm_drm_bridge_alloc()
 * adapt the code wherever using the channels
 * remove the is_available flag, now "ch != NULL" is equivalent

Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>

---

Cc: Liu Ying <victor.liu@....com>

Changes in v3:
- fix NULL pointer deref in .remove and remove is_available bool

Changes in v2: none
---
 .../gpu/drm/bridge/imx/imx8qxp-pixel-combiner.c    | 27 +++++++++++-----------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-combiner.c b/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-combiner.c
index 1f6fd488e7039e943351006d3373009f0c15cb08..8517b1c953d4e0fb9f5b6dbe25fbaaa63eef2b33 100644
--- a/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-combiner.c
+++ b/drivers/gpu/drm/bridge/imx/imx8qxp-pixel-combiner.c
@@ -63,12 +63,11 @@ struct imx8qxp_pc_channel {
 	struct drm_bridge *next_bridge;
 	struct imx8qxp_pc *pc;
 	unsigned int stream_id;
-	bool is_available;
 };
 
 struct imx8qxp_pc {
 	struct device *dev;
-	struct imx8qxp_pc_channel ch[2];
+	struct imx8qxp_pc_channel *ch[2];
 	struct clk *clk_apb;
 	void __iomem *base;
 };
@@ -307,7 +306,14 @@ static int imx8qxp_pc_bridge_probe(struct platform_device *pdev)
 			goto free_child;
 		}
 
-		ch = &pc->ch[i];
+		ch = devm_drm_bridge_alloc(dev, struct imx8qxp_pc_channel, bridge,
+					   &imx8qxp_pc_bridge_funcs);
+		if (IS_ERR(ch)) {
+			ret = PTR_ERR(ch);
+			goto free_child;
+		}
+
+		pc->ch[i] = ch;
 		ch->pc = pc;
 		ch->stream_id = i;
 
@@ -333,9 +339,7 @@ static int imx8qxp_pc_bridge_probe(struct platform_device *pdev)
 		of_node_put(remote);
 
 		ch->bridge.driver_private = ch;
-		ch->bridge.funcs = &imx8qxp_pc_bridge_funcs;
 		ch->bridge.of_node = child;
-		ch->is_available = true;
 
 		drm_bridge_add(&ch->bridge);
 	}
@@ -345,8 +349,8 @@ static int imx8qxp_pc_bridge_probe(struct platform_device *pdev)
 free_child:
 	of_node_put(child);
 
-	if (i == 1 && pc->ch[0].next_bridge)
-		drm_bridge_remove(&pc->ch[0].bridge);
+	if (i == 1 && pc->ch[0]->next_bridge)
+		drm_bridge_remove(&pc->ch[0]->bridge);
 
 	pm_runtime_disable(dev);
 	return ret;
@@ -359,13 +363,10 @@ static void imx8qxp_pc_bridge_remove(struct platform_device *pdev)
 	int i;
 
 	for (i = 0; i < 2; i++) {
-		ch = &pc->ch[i];
-
-		if (!ch->is_available)
-			continue;
+		ch = pc->ch[i];
 
-		drm_bridge_remove(&ch->bridge);
-		ch->is_available = false;
+		if (ch)
+			drm_bridge_remove(&ch->bridge);
 	}
 
 	pm_runtime_disable(&pdev->dev);

-- 
2.49.0