linux-kernel - [PATCH v2 02/16] drm/panel: get the panel returned by of_drm_find

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Message-Id: <20250619-b4-of_drm_find_panel_part1-v2-2-0df94aecc43d@redhat.com>
Date: Thu, 19 Jun 2025 14:15:54 -0500
From: Anusha Srivatsa <asrivats@...hat.com>
To: Neil Armstrong <neil.armstrong@...aro.org>, 
 Jessica Zhang <jessica.zhang@....qualcomm.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>, 
 Inki Dae <inki.dae@...sung.com>, Jagan Teki <jagan@...rulasolutions.com>, 
 Marek Szyprowski <m.szyprowski@...sung.com>, 
 Andrzej Hajda <andrzej.hajda@...el.com>, Robert Foss <rfoss@...nel.org>, 
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
 Chen-Yu Tsai <wens@...e.org>, Samuel Holland <samuel@...lland.org>, 
 Seung-Woo Kim <sw0312.kim@...sung.com>, 
 Kyungmin Park <kyungmin.park@...sung.com>, 
 Krzysztof Kozlowski <krzk@...nel.org>, 
 Alim Akhtar <alim.akhtar@...sung.com>, 
 Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>, 
 Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>, 
 Kieran Bingham <kieran.bingham+renesas@...asonboard.com>, 
 Geert Uytterhoeven <geert+renesas@...der.be>, 
 Magnus Damm <magnus.damm@...il.com>, Biju Das <biju.das.jz@...renesas.com>, 
 Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, 
 Alain Volmat <alain.volmat@...s.st.com>, 
 Raphael Gallais-Pou <rgallaispou@...il.com>, Stefan Agner <stefan@...er.ch>, 
 Alison Wang <alison.wang@....com>, Linus Walleij <linus.walleij@...aro.org>, 
 Thierry Reding <thierry.reding@...il.com>, 
 Mikko Perttunen <mperttunen@...dia.com>, 
 Jonathan Hunter <jonathanh@...dia.com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev, 
 linux-samsung-soc@...r.kernel.org, linux-renesas-soc@...r.kernel.org, 
 linux-tegra@...r.kernel.org, Anusha Srivatsa <asrivats@...hat.com>
Subject: [PATCH v2 02/16] drm/panel: get the panel returned by
 of_drm_find_panel()

of_drm_find_panel() returns a panel pointer that the caller
holds. With refcounting in place, increment the refcount
of the panel that is returned. This reference has to be put()
by the caller.
Document the behaviour expected from all callers of this
API.

Signed-off-by: Anusha Srivatsa <asrivats@...hat.com>
---
 drivers/gpu/drm/drm_panel.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
index ced6b08923b2150ebda6e1d9001517103895def1..a3aab725f91f76661185b3ebdf3d9b337bdf230f 100644
--- a/drivers/gpu/drm/drm_panel.c
+++ b/drivers/gpu/drm/drm_panel.c
@@ -401,6 +401,9 @@ EXPORT_SYMBOL(__devm_drm_panel_alloc);
  * Searches the set of registered panels for one that matches the given device
  * tree node. If a matching panel is found, return a pointer to it.
  *
+ * The refcount of the returned panel is incremented. Use drm_panel_put()
+ * at the caller side to maintain the count.
+ *
  * Return: A pointer to the panel registered for the specified device tree
  * node or an ERR_PTR() if no panel matching the device tree node can be found.
  *
@@ -422,6 +425,7 @@ struct drm_panel *of_drm_find_panel(const struct device_node *np)
 	list_for_each_entry(panel, &panel_list, list) {
 		if (panel->dev->of_node == np) {
 			mutex_unlock(&panel_lock);
+			drm_panel_get(panel);
 			return panel;
 		}
 	}

-- 
2.48.1