linux-kernel - [PATCH v7 08/11] drm/atomic-helper: put the bridge returned by drm_bridge_chain_get_first

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Message-Id: <20250314-drm-bridge-refcount-v7-8-152571f8c694@bootlin.com>
Date: Fri, 14 Mar 2025 11:31:21 +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 v7 08/11] drm/atomic-helper: put the bridge returned by
 drm_bridge_chain_get_first_bridge()

The bridge returned by drm_bridge_chain_get_first_bridge() is
refcounted. Put it when done.

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

---

Note: I suspect most or all of the involved functions here could just
receive the encoder instead of the first bridge in the chain, and then walk
the encoder chain on their own. For the sake of simplicity and to show how
to put a bridge in general I've kept this patch in this form, for the time
being.

This patch was added in v7.
---
 drivers/gpu/drm/drm_atomic_helper.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 5302ab3248985d3e0a47e40fd3deb7ad0d9f775b..fcd9139ef98e9f57659b7e447cf57702e99a5165 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -455,6 +455,7 @@ mode_fixup(struct drm_atomic_state *state)
 		ret = drm_atomic_bridge_chain_check(bridge,
 						    new_crtc_state,
 						    new_conn_state);
+		drm_bridge_put(bridge);
 		if (ret) {
 			drm_dbg_atomic(encoder->dev, "Bridge atomic check failed\n");
 			return ret;
@@ -526,6 +527,7 @@ static enum drm_mode_status mode_valid_path(struct drm_connector *connector,
 	bridge = drm_bridge_chain_get_first_bridge(encoder);
 	ret = drm_bridge_chain_mode_valid(bridge, &connector->display_info,
 					  mode);
+	drm_bridge_put(bridge);
 	if (ret != MODE_OK) {
 		drm_dbg_atomic(encoder->dev, "[BRIDGE] mode_valid() failed\n");
 		return ret;
@@ -1226,6 +1228,7 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *state)
 		}
 
 		drm_atomic_bridge_chain_post_disable(bridge, state);
+		drm_bridge_put(bridge);
 	}
 
 	for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
@@ -1433,6 +1436,7 @@ crtc_set_mode(struct drm_device *dev, struct drm_atomic_state *state)
 
 		bridge = drm_bridge_chain_get_first_bridge(encoder);
 		drm_bridge_chain_mode_set(bridge, mode, adjusted_mode);
+		drm_bridge_put(bridge);
 	}
 }
 
@@ -1564,6 +1568,7 @@ void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
 		}
 
 		drm_atomic_bridge_chain_enable(bridge, state);
+		drm_bridge_put(bridge);
 	}
 
 	drm_atomic_helper_commit_writebacks(dev, state);

-- 
2.48.1