linux-kernel - Re: [PATCH v8 3/5] drm/mxsfb: put the bridge returned by drm_bridge_chain_get_first

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Message-ID: <6ed34611-d2fe-4c9c-8b00-0939ac407e07@nxp.com>
Date: Mon, 23 Jun 2025 11:06:37 +0800
From: Liu Ying <victor.liu@....com>
To: Luca Ceresoli <luca.ceresoli@...tlin.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 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>,
 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>
Cc: Hui Pu <Hui.Pu@...ealthcare.com>,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v8 3/5] drm/mxsfb: put the bridge returned by
 drm_bridge_chain_get_first_bridge()

On 06/21/2025, Luca Ceresoli wrote:
> The bridge returned by drm_bridge_chain_get_first_bridge() is
> refcounted. Put it when done. Use a scope-based free action to catch all
> the code paths.
> 
> Reviewed-by: Maxime Ripard <mripard@...nel.org>
> Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
> ---
> 
> This patch was added in v7.
> ---
>  drivers/gpu/drm/mxsfb/lcdif_kms.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/mxsfb/lcdif_kms.c b/drivers/gpu/drm/mxsfb/lcdif_kms.c
> index dbd42cc1da87f82ef9cd4ccc70cdecbe56035174..21311cf5efee7d26c80316bffe80dd2bfed02238 100644
> --- a/drivers/gpu/drm/mxsfb/lcdif_kms.c
> +++ b/drivers/gpu/drm/mxsfb/lcdif_kms.c
> @@ -433,7 +433,6 @@ static int lcdif_crtc_atomic_check(struct drm_crtc *crtc,
>  	struct drm_connector *connector;
>  	struct drm_encoder *encoder;
>  	struct drm_bridge_state *bridge_state;
> -	struct drm_bridge *bridge;
>  	u32 bus_format, bus_flags;
>  	bool format_set = false, flags_set = false;
>  	int ret, i;
> @@ -448,6 +447,8 @@ static int lcdif_crtc_atomic_check(struct drm_crtc *crtc,
>  
>  	/* Try to find consistent bus format and flags across first bridges. */
>  	for_each_new_connector_in_state(state, connector, connector_state, i) {
> +		struct drm_bridge *bridge __free(drm_bridge_put) = NULL;
> +
>  		if (!connector_state->crtc)
>  			continue;

To avoid the unnecessary cleanup for !connector_state->crtc, I would write:

-8<-
--- a/drivers/gpu/drm/mxsfb/lcdif_kms.c
+++ b/drivers/gpu/drm/mxsfb/lcdif_kms.c
@@ -433,7 +433,6 @@ static int lcdif_crtc_atomic_check(struct drm_crtc *crtc,
        struct drm_connector *connector;
        struct drm_encoder *encoder;
        struct drm_bridge_state *bridge_state;
-       struct drm_bridge *bridge;
        u32 bus_format, bus_flags;
        bool format_set = false, flags_set = false;
        int ret, i;
@@ -453,7 +452,8 @@ static int lcdif_crtc_atomic_check(struct drm_crtc *crtc,
 
                encoder = connector_state->best_encoder;
 
-               bridge = drm_bridge_chain_get_first_bridge(encoder);
+               struct drm_bridge *bridge __free(drm_bridge_put) =
+                               drm_bridge_chain_get_first_bridge(encoder);
                if (!bridge)
                        continue;
-8<-

>  
> 

-- 
Regards,
Liu Ying