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@kernel.org>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.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;
 

-- 
2.49.0

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@kernel.org>
> Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.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

On Mon, 23 Jun 2025 11:06:37 +0800
Liu Ying <victor.liu@nxp.com> wrote:

[...]

> > 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);

Good idea, I probably didn't think about it because I was grown up in a
world where all declarations must before the code. :-)

Changing this in v9.

Luca

-- 
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com