[PATCH v2 16/17] ASoC: Intel: bdw_rt286: Refactor suspend/resume

[Pierre-Louis Bossart]

> Jacks are often initialized during dai_link initialization which is
> completely out of platform_device area. This report made me think
> further - if we assign jack in dai_link->init(), we should be able to
> drop it in dai_link->exit().
> 
> Not exactly! ->init() is done once card components are already accounted
> for (available for use) but snd_soc_link_exit() is called during
> snd_soc_remove_pcm_runtime() when card components are available no
> longer - soc_remove_link_components().
> 
> TLDR: teardown path is not symmetric with its counterpart, perhaps a
> problem yet to be addressed. I'll see if moving the jack-NULLing to
> codec's DAI ->remove() won't be a better temporary (?) solution than
> reverting to platform_device->remove() usage.

It's a problem that impacted other platforms, see e.g.

static void kabylake_rt5660_codec_exit(struct snd_soc_pcm_runtime *rtd)
{
	struct kbl_codec_private *ctx = snd_soc_card_get_drvdata(rtd->card);

	/*
	 * The .exit() can be reached without going through the .init()
	 * so explicitly test if the gpiod is valid
	 */
	if (!IS_ERR_OR_NULL(ctx->gpio_lo_mute))
		gpiod_put(ctx->gpio_lo_mute);
}

I vaguely recall hitting this myself when working with codec properties.
It's worthy of a comment in the ASoC header to make sure this is better
known/shared.

I see in other drivers that the use of component_set_jack() is
symmetrical between .init and .exit, so far we haven't seen any issues
with sof_rt5682.c and others.