Re: [PATCH v2 1/3] ASoC: soc-pcm: add option to start DMA after DAI

["Amadeusz Sławiński" <amadeuszx.slawinski@linux.intel.com>]

On 2/17/2023 1:41 PM, Claudiu Beznea wrote:
> Add option to start DMA component after DAI trigger. This is done
> by filling the new struct snd_soc_component_driver::start_dma_last.
> 
> Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
> ---
>   include/sound/soc-component.h |  2 ++
>   sound/soc/soc-pcm.c           | 27 ++++++++++++++++++++++-----
>   2 files changed, 24 insertions(+), 5 deletions(-)
> 
> diff --git a/include/sound/soc-component.h b/include/sound/soc-component.h
> index 3203d35bc8c1..0814ed143864 100644
> --- a/include/sound/soc-component.h
> +++ b/include/sound/soc-component.h
> @@ -190,6 +190,8 @@ struct snd_soc_component_driver {
>   	bool use_dai_pcm_id;	/* use DAI link PCM ID as PCM device number */
>   	int be_pcm_base;	/* base device ID for all BE PCMs */
>   
> +	unsigned int start_dma_last;
> +
>   #ifdef CONFIG_DEBUG_FS
>   	const char *debugfs_prefix;
>   #endif
> diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
> index 005b179a770a..5eb056b942ce 100644
> --- a/sound/soc/soc-pcm.c
> +++ b/sound/soc/soc-pcm.c
> @@ -1088,22 +1088,39 @@ static int soc_pcm_hw_params(struct snd_pcm_substream *substream,
>   static int soc_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
>   {
>   	struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
> -	int ret = -EINVAL, _ret = 0;
> +	struct snd_soc_component *component;
> +	int ret = -EINVAL, _ret = 0, start_dma_last = 0, i;
>   	int rollback = 0;
>   
>   	switch (cmd) {
>   	case SNDRV_PCM_TRIGGER_START:
>   	case SNDRV_PCM_TRIGGER_RESUME:
>   	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
> +		/* Do we need to start dma last? */
> +		for_each_rtd_components(rtd, i, component) {
> +			if (component->driver->start_dma_last) {
> +				start_dma_last = 1;
> +				break;
> +			}
> +		}
> +
>   		ret = snd_soc_link_trigger(substream, cmd, 0);
>   		if (ret < 0)
>   			goto start_err;
>   
> -		ret = snd_soc_pcm_component_trigger(substream, cmd, 0);
> -		if (ret < 0)
> -			goto start_err;
> +		if (start_dma_last) {
> +			ret = snd_soc_pcm_dai_trigger(substream, cmd, 0);
> +			if (ret < 0)
> +				goto start_err;
> +
> +			ret = snd_soc_pcm_component_trigger(substream, cmd, 0);
> +		} else {
> +			ret = snd_soc_pcm_component_trigger(substream, cmd, 0);
> +			if (ret < 0)
> +				goto start_err;
>   
> -		ret = snd_soc_pcm_dai_trigger(substream, cmd, 0);
> +			ret = snd_soc_pcm_dai_trigger(substream, cmd, 0);
> +		}
>   start_err:
>   		if (ret < 0)
>   			rollback = 1;

Can all of the above be implemented similarly to already present 
stop_dma_first? It looks similar and I don't see reason to have one flag 
in snd_soc_component_driver and other in snd_soc_dai_link.