If we focus to soc_bind_dai_link() at snd_soc_instantiate_card(),
we will notice very complex operation.

static int snd_soc_instantiate_card(...)
{
	...
	/*
	 * (1) Bind dai_link via card pre-linked dai_link
	 *
	 * Bind dai_link via card pre-linked.
	 * 1 dai_link will be 1 rtd, and connected to card.
	 * for_each_card_prelinks() is for card pre-linked dai_link.
	 *
	 * Image
	 *
	 * card
	 * - rtd(A)
	 * - rtd(A)
	 */
	for_each_card_prelinks(card, i, dai_link) {
		ret = soc_bind_dai_link(card, dai_link);
		...
	}
	...
	/*
	 * (2) Connect card pre-linked dai_link to card list
	 *
	 * Connect all card pre-linked dai_link to *card list*.
	 * Here, (A) means from card pre-linked.
	 *
	 * Image
	 *
	 * card		card list
	 *  - rtd(A)	 - dai_link(A)
	 *  - rtd(A)	 - dai_link(A)
	 *  - ...	 - ...
	 */
	for_each_card_prelinks(card, i, dai_link) {
		ret = snd_soc_add_dai_link(card, dai_link);
		...
	}
	...
	/*
	 * (3) Probe binded component
	 *
	 * Each rtd has many components.
	 * Here probes each rtd connected components.
	 * rtd(A) in Image is the probe target.
	 *
	 * During this component probe, topology may add new dai_link to
	 * *card list* by using snd_soc_add_dai_link() which is
	 * used at (2).
	 * Here, (B) means from topology
	 *
	 * Image
	 *
	 * card		card list
	 *  - rtd(A)	 - dai_link(A)
	 *  - rtd(A)	 - dai_link(A)
	 *  - ...	 - ...
	 *		 - dai_link(B)
	 *		 - dai_link(B)
	 */
	ret = soc_probe_link_components(card);
	...

	/*
	 * (4) Bind dai_link again
	 *
	 * Bind dai_link again for topology.
	 * Note, (1) used for_each_card_prelinks(),
	 * here is using  for_each_card_links()
	 *
	 * This means from card list.
	 * As Image indicating, it has dai_link(A) (from card pre-link)
	 * and dai_link(B) (from topology).
	 * main target here is dai_link(B).
	 * soc_bind_dai_link() ignores already used
	 * dai_link (= dai_link(A))
	 *
	 * Image
	 *
	 * card		card list
	 *  - rtd(A)	 - dai_link(A)
	 *  - rtd(A)	 - dai_link(A)
	 *  - ...	 - ...
	 *  - rtd(B)	 - dai_link(B)
	 *  - rtd(B)	 - dai_link(B)
	 */
	for_each_card_links(card, dai_link) {
		ret = soc_bind_dai_link(card, dai_link);
		...
	}
	...
}

As you see above, it is doing very complex method.
The problem is binding dai_link via "card pre-linked" (= (1)) and
"topology added dai_link" (= (3)) are separated.
The code can be simple if we can bind dai_link when dai_link
is connected to *card list*.
This patch do it.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/878sou3jnn.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>