Re: [PATCH v7 06/11] drm/bridge: get the bridge returned by drm_bridge_chain_get_first_bridge()

[Maxime Ripard <mripard@kernel.org>]

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On Fri, Mar 14, 2025 at 11:31:19AM +0100, Luca Ceresoli wrote:
> drm_bridge_chain_get_first_bridge() returns a bridge pointer that the
> caller could hold for a long time. Increment the refcount of the returned
> bridge and document it must be put by the caller.
> 
> Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
> 
> ---
> 
> This patch was added in v7.
> ---
>  include/drm/drm_bridge.h | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> index a5accd64c364ebb57903ae1e7459034ad9ebf4f3..d9777d5f2e9ef006f0062e4507bce99df4146cd9 100644
> --- a/include/drm/drm_bridge.h
> +++ b/include/drm/drm_bridge.h
> @@ -1105,6 +1105,9 @@ drm_bridge_get_prev_bridge(struct drm_bridge *bridge)
>   * drm_bridge_chain_get_first_bridge() - Get the first bridge in the chain
>   * @encoder: encoder object
>   *
> + * The refcount of the returned bridge is incremented. Use drm_bridge_put()
> + * when done with it.
> + *
>   * RETURNS:
>   * the first bridge in the chain, or NULL if @encoder has no bridge attached
>   * to it.
> @@ -1112,8 +1115,8 @@ drm_bridge_get_prev_bridge(struct drm_bridge *bridge)
>  static inline struct drm_bridge *
>  drm_bridge_chain_get_first_bridge(struct drm_encoder *encoder)
>  {
> -	return list_first_entry_or_null(&encoder->bridge_chain,
> -					struct drm_bridge, chain_node);
> +	return drm_bridge_get(list_first_entry_or_null(&encoder->bridge_chain,
> +						       struct drm_bridge, chain_node));
>  }

We'll need to modify drm_bridge_get_next_bridge, drm_bridge_get_prev_bridge, and
drm_for_each_bridge_in_chain in a similar manner, but for this one

Reviewed-by: Maxime Ripard <mripard@kernel.org>

Maxime

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