[alsa-devel] [PATCH v3 2/3] ASoC: Add Multi CPU DAI support for PCM ops

[Shreyas NC]

On Mon, Apr 30, 2018 at 05:22:36PM +0100, Charles Keepax wrote:
> > @@ -361,7 +386,16 @@ 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);
> 
> Do you want cpu_bits at the end here? You are not going to get
> the max of the cpu_bits here, you will end up with the max of the
> CODEC bits and the last CPU bits?
> 

You are right, will fix this :)

> > @@ -427,30 +464,47 @@ 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 && rtd->num_cpu_dai == 1) {
> > +			chan_min = cpu_stream->channels_min;
> > +			chan_max = cpu_stream->channels_max;
> > +		}
> 
> This still doesn't quite look like, I am not seeing how the
> multiple CPU DAI and single CPU DAI cases differ with respect to
> whether we should ignore the CODEC channel settings?
> 

Ok

> > +
> > +		hw->channels_min = max(hw->channels_min, chan_min);
> > +		hw->channels_min = max(hw->channels_min,
> > +					cpu_stream->channels_min);
> > +		hw->channels_max = min(hw->channels_max,
> > +					cpu_stream->channels_max);
> > +		hw->channels_max = min(hw->channels_max,
> > +					cpu_stream->channels_max);
> > +
> > +		if (hw->formats)
> > +			hw->formats &= formats & cpu_stream->formats;
> 
> Minor nit.
> 
> This feels a little funny now, since we are anding each CPU
> formats with the CODEC formats, and then anding them into the
> result.
> 
> Feels like we should just and in the CODEC format once.

Yes, makes sense. Thanks :)

> 
> > +		else
> > +			hw->formats = formats & cpu_stream->formats;
> 
> > +
> > +		hw->rates = snd_pcm_rate_mask_intersect(rates,
> > +						cpu_stream->rates);
> 
> I think this is broken since the rates will end up and the
> intersection of the last CPU DAI rates and the CODEC rates, not
> an intersection of all the CPU rates.
> 

Ok, will fix this :)
I have had a tough time in handling this function :(

> > @@ -602,7 +668,7 @@ static int soc_pcm_open(struct snd_pcm_substream *substream)
> >  	}
> >  
> >  	pr_debug("ASoC: %s <-> %s info:\n",
> > -			codec_dai_name, cpu_dai->name);
> > +			codec_dai_name, cpu_dai_name);
> >  	pr_debug("ASoC: rate mask 0x%x\n", runtime->hw.rates);
> >  	pr_debug("ASoC: min ch %d max ch %d\n", runtime->hw.channels_min,
> >  		 runtime->hw.channels_max);
> > @@ -649,9 +715,13 @@ static int soc_pcm_open(struct snd_pcm_substream *substream)
> >  		platform->driver->ops->close(substream);
> >  
> >  platform_err:
> > -	if (cpu_dai->driver->ops->shutdown)
> > -		cpu_dai->driver->ops->shutdown(substream, cpu_dai);
> > -out:
> > +	j = rtd->num_cpu_dai;
> > +	while (--j >= 0) {
> > +		cpu_dai = rtd->cpu_dais[j];
> > +		if (cpu_dai->driver->ops->shutdown)
> > +			cpu_dai->driver->ops->shutdown(substream, cpu_dai);
> > +	}
> > +
> 
> This will call shutdown for DAIs that never had startup called on
> them, probably better to avoid that.
> 

Ok, will fix this.

> > @@ -1070,12 +1168,18 @@ static int soc_pcm_hw_params(struct snd_pcm_substream *substream,
> >  		platform->driver->ops->hw_free(substream);
> >  
> >  platform_err:
> > -	if (cpu_dai->driver->ops->hw_free)
> > -		cpu_dai->driver->ops->hw_free(substream, cpu_dai);
> > +	j = rtd->num_cpu_dai;
> >  
> >  interface_err:
> >  	i = rtd->num_codecs;
> >  
> > +	while (--j >= 0) {
> > +		cpu_dai = rtd->cpu_dais[j];
> > +
> > +		if (cpu_dai->driver->ops && cpu_dai->driver->ops->hw_free)
> > +			cpu_dai->driver->ops->hw_free(substream, cpu_dai);
> > +	}
> > +
> 
> Minor nit might be nicer to add this before the i = since that
> kinda relates to the code underneath.
> 

Sure, that aids readability. I will check if we can do that at other places
as well :)

Thanks for the review!

--Shreyas
--