Re: [PATCH 2/3] ASoC: Add Multi CPU DAI support for PCM ops

[Charles Keepax <ckeepax@opensource.cirrus.com>]

On Tue, Mar 06, 2018 at 04:30:29PM +0530, Shreyas NC wrote:
> This adds support for Multi CPU DAIs in PCM ops and stream
> handling functions.
> 
> Signed-off-by: Shreyas NC <shreyas.nc@intel.com>
> ---
> @@ -313,13 +333,17 @@ static int soc_pcm_params_symmetry(struct snd_pcm_substream *substream,
>  static bool soc_pcm_has_symmetry(struct snd_pcm_substream *substream)
>  {
>  	struct snd_soc_pcm_runtime *rtd = substream->private_data;
> -	struct snd_soc_dai_driver *cpu_driver = rtd->cpu_dai->driver;
>  	struct snd_soc_dai_link *link = rtd->dai_link;
> -	unsigned int symmetry, i;
> +	unsigned int symmetry = 0, i;
>  
> -	symmetry = cpu_driver->symmetric_rates || link->symmetric_rates ||
> -		cpu_driver->symmetric_channels || link->symmetric_channels ||
> -		cpu_driver->symmetric_samplebits || link->symmetric_samplebits;
> +	/* Apply symmetery for multiple cpu dais */
> +	for (i = 0; i < rtd->num_cpu_dai; i++)
> +		symmetry = rtd->cpu_dais[i]->driver->symmetric_rates ||
> +						link->symmetric_rates ||
> +			rtd->cpu_dais[i]->driver->symmetric_channels ||
> +						link->symmetric_channels ||
> +			rtd->cpu_dais[i]->driver->symmetric_samplebits ||
> +						link->symmetric_samplebits;

No need to bring the link-> stuff into the loop, it won't change
on each iteration. Would also make the code look neater to leave
it before the loop.

>  
>  	for (i = 0; i < rtd->num_codecs; i++)
>  		symmetry = symmetry ||
> @@ -347,10 +371,10 @@ static void soc_pcm_set_msb(struct snd_pcm_substream *substream, int bits)
>  static void soc_pcm_apply_msb(struct snd_pcm_substream *substream)
>  {
>  	struct snd_soc_pcm_runtime *rtd = substream->private_data;
> -	struct snd_soc_dai *cpu_dai = rtd->cpu_dai;
> +	struct snd_soc_dai *cpu_dai;
>  	struct snd_soc_dai *codec_dai;
>  	int i;
> -	unsigned int bits = 0, cpu_bits;
> +	unsigned int bits = 0, cpu_bits = 0;
>  
>  	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
>  		for (i = 0; i < rtd->num_codecs; i++) {
> @@ -361,7 +385,17 @@ static void soc_pcm_apply_msb(struct snd_pcm_substream *substream)
>  			}
>  			bits = max(codec_dai->driver->playback.sig_bits, bits);
>  		}
> -		cpu_bits = cpu_dai->driver->playback.sig_bits;
> +
> +		for (i = 0; i < rtd->num_cpu_dai; i++) {
> +			cpu_dai = rtd->cpu_dais[i];
> +			if (cpu_dai->driver->playback.sig_bits == 0) {
> +				cpu_bits = 0;
> +				break;
> +			}
> +
> +			cpu_bits = max(
> +				    cpu_dai->driver->playback.sig_bits,	bits);

Can help but feel this would look nicer if you only wrapped the
second argument down a line. Although tbf its only 1 character so
you could probably just run over the line length as well.

> @@ -427,30 +464,41 @@ static void soc_pcm_init_runtime_hw(struct snd_pcm_substream *substream)
>  		rates = snd_pcm_rate_mask_intersect(codec_stream->rates, rates);
>  	}
>  
> -	/*
> -	 * chan min/max cannot be enforced if there are multiple CODEC DAIs
> -	 * connected to a single CPU DAI, use CPU DAI's directly and let
> -	 * channel allocation be fixed up later
> -	 */
> -	if (rtd->num_codecs > 1) {
> -		chan_min = cpu_stream->channels_min;
> -		chan_max = cpu_stream->channels_max;
> -	}
> +	for (i = 0; i < rtd->num_cpu_dai; i++) {
> +		cpu_dai_drv = rtd->cpu_dais[i]->driver;
>  
> -	hw->channels_min = max(chan_min, cpu_stream->channels_min);
> -	hw->channels_max = min(chan_max, cpu_stream->channels_max);
> -	if (hw->formats)
> -		hw->formats &= formats & cpu_stream->formats;
> -	else
> -		hw->formats = formats & cpu_stream->formats;
> -	hw->rates = snd_pcm_rate_mask_intersect(rates, cpu_stream->rates);
> +		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
> +			cpu_stream = &cpu_dai_drv->playback;
> +		else
> +			cpu_stream = &cpu_dai_drv->capture;
>  
> -	snd_pcm_limit_hw_rates(runtime);
> +		/*
> +		 * chan min/max cannot be enforced if there are multiple
> +		 * CODEC DAIs connected to a single CPU DAI, use CPU DAI's
> +		 * directly and let channel allocation be fixed up later
> +		 */
> +		if (rtd->num_codecs > 1) {
> +			chan_min = cpu_stream->channels_min;
> +			chan_max = cpu_stream->channels_max;
> +		}
> +
> +		hw->channels_min = max(chan_min, cpu_stream->channels_min);
> +		hw->channels_max = min(chan_max, cpu_stream->channels_max);
> +		if (hw->formats)
> +			hw->formats &= formats & cpu_stream->formats;
> +		else
> +			hw->formats = formats & cpu_stream->formats;
>  

I don't think actually ends up with the correct values in
hw->channels_min/max. Nothing compares one iteration of the
loop to the previous one so you don't end up with the min/max for
all the CPU DAIs you just end up with the values from the last
CPU DAI.

>  /*
> @@ -465,12 +513,15 @@ static int soc_pcm_open(struct snd_pcm_substream *substream)
>  	struct snd_soc_platform *platform = rtd->platform;
>  	struct snd_soc_component *component;
>  	struct snd_soc_rtdcom_list *rtdcom;
> -	struct snd_soc_dai *cpu_dai = rtd->cpu_dai;
> +	struct snd_soc_dai *cpu_dai;
>  	struct snd_soc_dai *codec_dai;
>  	const char *codec_dai_name = "multicodec";
> -	int i, ret = 0, __ret;
> +	const char *cpu_dai_name = "multicpu";
> +	int i, ret = 0, __ret, j;
> +
> +	for (i = 0; i < rtd->num_cpu_dai; i++)
> +		pinctrl_pm_select_default_state(rtd->cpu_dais[i]->dev);
>  
> -	pinctrl_pm_select_default_state(cpu_dai->dev);
>  	for (i = 0; i < rtd->num_codecs; i++)
>  		pinctrl_pm_select_default_state(rtd->codec_dais[i]->dev);
>  
> @@ -483,12 +534,15 @@ static int soc_pcm_open(struct snd_pcm_substream *substream)
>  	mutex_lock_nested(&rtd->pcm_mutex, rtd->pcm_subclass);
>  
>  	/* startup the audio subsystem */
> -	if (cpu_dai->driver->ops->startup) {
> -		ret = cpu_dai->driver->ops->startup(substream, cpu_dai);
> -		if (ret < 0) {
> -			dev_err(cpu_dai->dev, "ASoC: can't open interface"
> -				" %s: %d\n", cpu_dai->name, ret);
> -			goto out;
> +	for (i = 0; i < rtd->num_cpu_dai; i++) {
> +		cpu_dai = rtd->cpu_dais[i];
> +		if (cpu_dai->driver->ops->startup) {
> +			ret = cpu_dai->driver->ops->startup(substream, cpu_dai);
> +			if (ret < 0) {
> +				dev_err(cpu_dai->dev, "ASoC: can't open interface %s: %d\n",
> +							cpu_dai->name, ret);
> +				goto out;

I don't believe this jumps to the right place anymore since you
need to shutdown any CPU DAIs you have already started up.

> @@ -1276,8 +1388,12 @@ static snd_pcm_uframes_t soc_pcm_pointer(struct snd_pcm_substream *substream)
>  		break;
>  	}
>  
> -	if (cpu_dai->driver->ops->delay)
> -		delay += cpu_dai->driver->ops->delay(substream, cpu_dai);
> +	for (i = 0; i < rtd->num_cpu_dai; i++) {
> +		cpu_dai = rtd->cpu_dais[i];
> +		if (cpu_dai->driver->ops->delay)
> +			delay += cpu_dai->driver->ops->delay(substream,
> +								cpu_dai);
> +	}

I am not clear we should be adding the delays here can't they all
run in parallel? In which case shouldn't we be taking the max?

> @@ -2998,8 +3139,13 @@ int soc_new_pcm(struct snd_soc_pcm_runtime *rtd, int num)
>  				capture = 1;
>  		}
>  
> -		capture = capture && cpu_dai->driver->capture.channels_min;
> -		playback = playback && cpu_dai->driver->playback.channels_min;
> +		for (i = 0; i < rtd->num_cpu_dai; i++) {
> +			cpu_dai = rtd->cpu_dais[i];
> +			capture = capture &&
> +					cpu_dai->driver->capture.channels_min;
> +			playback = playback &&
> +					cpu_dai->driver->playback.channels_min;
> +		}

This doesn't look right either since you will end up with the
values for the last CPU DAI surely you want some sort of combined
value.

I am also a little nervous about the mapping between widgets and
DAIs in dpcm_prune_paths. But I don't think I really understand
that bit of the code well enough to provide good comments.
Hopefully someone with more understanding than me can have a look
:-)

Thanks,
Charles