Re: [PATCH v16 01/22] media: mc: Add INTERNAL pad flag

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Fallback fwnode pad matching incorrectly maps external endpoints to internal pads.
--

commit 8c2ba56726bfa940940f5ffec523ef8ae74466ed
Author: Sakari Ailus <sakari.ailus@linux.intel.com>
Date:   Mon Aug 31 13:21:20 2026 +0000

    media: mc: Add INTERNAL pad flag
    
    Internal sink pads will be used as routing endpoints in V4L2 [GS]_ROUTING
    IOCTLs, to indicate that the stream begins in the entity. Internal sink
    pads are pads that have both SINK and INTERNAL flags set.
    
    Also prevent creating links to pads that have been flagged as internal and
    initialising SOURCE pads with INTERNAL flag set.

> diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
> index 3fa0bc687851b..7938f785e2e3c 100644
> --- a/drivers/media/mc/mc-entity.c
> +++ b/drivers/media/mc/mc-entity.c
[ ... ]
> @@ -1118,7 +1123,8 @@ int media_get_pad_index(struct media_entity *entity, u32 pad_type,
>  
>  	for (i = 0; i < entity->num_pads; i++) {
>  		if ((entity->pads[i].flags &
> -		     (MEDIA_PAD_FL_SINK | MEDIA_PAD_FL_SOURCE)) != pad_type)
> +		     (MEDIA_PAD_FL_SINK | MEDIA_PAD_FL_SOURCE |
> +		      MEDIA_PAD_FL_INTERNAL)) != pad_type)
>  			continue;
>  
>  		if (entity->pads[i].sig_type == sig_type)

[Severity: Medium]
Will this patch also require updating media_entity_get_fwnode_pad() to handle
internal pads?

Looking at the fallback logic when an entity doesn't implement the
get_fwnode_pad operation, it iterates over all pads and returns the first pad
matching direction_flags:

drivers/media/mc/mc-entity.c:media_entity_get_fwnode_pad() {
    ...
		for (i = 0; i < entity->num_pads; i++) {
			if (entity->pads[i].flags & direction_flags)
				return i;
		}
    ...
}

Because internal pads have both MEDIA_PAD_FL_SINK and MEDIA_PAD_FL_INTERNAL
set, the bitwise AND will evaluate to true if direction_flags is
MEDIA_PAD_FL_SINK.

If this matches an internal pad before an external pad, the core framework
would attempt to wire an external fwnode link to the internal pad. This would
subsequently trigger the newly introduced WARN_ON in media_create_pad_link()
and return -EINVAL, causing device probe and link creation to fail.

Could media_entity_get_fwnode_pad() be updated to exclude internal pads?

> @@ -1148,6 +1154,9 @@ media_create_pad_link(struct media_entity *source, u16 source_pad,
>  		return -EINVAL;
>  	if (WARN_ON(!(sink->pads[sink_pad].flags & MEDIA_PAD_FL_SINK)))
>  		return -EINVAL;
> +	if (WARN_ON(source->pads[source_pad].flags & MEDIA_PAD_FL_INTERNAL) ||
> +	    WARN_ON(sink->pads[sink_pad].flags & MEDIA_PAD_FL_INTERNAL))
> +		return -EINVAL;
>  
>  	link = media_add_link(&source->links);
>  	if (link == NULL)

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260831-gmsl2-3_serdes-v16-0-4fa6e08bb514@analog.com?part=1