Re: [PATCH 04/10] ASoC: soc-dai: add snd_soc_dai_{to/from}_list()

["Alvin Šipraga" <alvin.sipraga@analog.com>]

On Mon, Sep 14, 2026 at 01:43:51AM +0000, Kuninori Morimoto wrote:
> DAI parameter will be capsuled soon, will be not enable to access from
> each drivers. add snd_soc_dai_{to/from}_list() to use for_each macro.
> 
> Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
> ---
>  include/sound/soc-component.h | 14 ++++++++++----
>  include/sound/soc-dai.h       |  2 ++
>  sound/soc/soc-dai.c           | 12 ++++++++++++
>  3 files changed, 24 insertions(+), 4 deletions(-)
> 
> diff --git a/include/sound/soc-component.h b/include/sound/soc-component.h
> index c49b59630101f..6c1acc984ecb0 100644
> --- a/include/sound/soc-component.h
> +++ b/include/sound/soc-component.h
> @@ -258,10 +258,16 @@ struct snd_soc_component {
>  	void *priv;
>  };
>  
> -#define for_each_component_dais(component, dai)\
> -	list_for_each_entry(dai, &(component)->dai_list, list)
> -#define for_each_component_dais_safe(component, dai, _dai)\
> -	list_for_each_entry_safe(dai, _dai, &(component)->dai_list, list)
> +#define for_each_component_dais(component, dai)				\
> +	for (dai = snd_soc_dai_from_list((component)->dai_list.next);	\
> +	     snd_soc_dai_to_list(dai) != &(component)->dai_list;	\
> +	     dai = snd_soc_dai_from_list(snd_soc_dai_to_list(dai)->next))
> +
> +#define for_each_component_dais_safe(component, dai, _dai)			\
> +	for (dai = snd_soc_dai_from_list((component)->dai_list.next),		\
> +	     _dai = snd_soc_dai_from_list(snd_soc_dai_to_list(dai)->next);	\
> +	     snd_soc_dai_to_list(dai) != &(component)->dai_list;		\
> +	     dai = _dai, _dai = snd_soc_dai_from_list(snd_soc_dai_to_list(_dai)->next))

Hmm, I guess later on you will have to also encapsulate components, and
so this header macro won't be allowed to expose (component)->dai_list
either. You will need some function like:

struct list_head *component_dai_list(c) {
  return &c->dai_list;
}

Then it will be kind of an explosion of function calls when
iterating:

#define for_each_component_dais(c, dai)                   \
  for (dai = dai_from_list(component_dai_list(c)->next),  \
       dai_to_list(dai) != component_dai_list(c);         \
       dai = dai_from_list(dai_to_list(n)->next))

That's 4 calls per iteration I think. Idk if it really matters.

But if you find yourself repeating the pattern, maybe some generic
helper like this would be useful:

#define list_for_each_opaque(pos, head, from_list)        \
  for (struct list_head *_h = (head), *_i = _h->next;     \
       _i != _h && ((pos) = from_list(_i), true);         \
       _i = _i->next)

It's ugly only once, but more optimal (only 1 call to from_list per
iteration, and one call of component_dai_list() at the start).

Then you can do:

#define for_each_component_dais(c, dai)                   \
  list_for_each_opaque(dai, component_dai_list(c), snd_soc_dai_from_list)


It's also fine this way though!


Reviewed-by: Alvin Šipraga <alvin.sipraga@analog.com>

Kind regards,
Alvin