RE: [PATCH v3 08/14] ASoC: amd: add ACP PDM DMA driver dai ops

From: "Mukunda, Vijendar" <Vijendar.Mukunda@amd.com>
To: Mark Brown <broonie@kernel.org>
Cc: "tiwai@suse.de" <tiwai@suse.de>,
	"Deucher, Alexander" <Alexander.Deucher@amd.com>,
	"alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>
Subject: RE: [PATCH v3 08/14] ASoC: amd: add ACP PDM DMA driver dai ops
Date: Tue, 19 May 2020 11:37:39 +0000	[thread overview]
Message-ID: <DM6PR12MB2633954F20E044F44CA89D5497B90@DM6PR12MB2633.namprd12.prod.outlook.com> (raw)
In-Reply-To: <20200519111907.GD4611@sirena.org.uk>

> -----Original Message-----
> From: Mark Brown <broonie@kernel.org>
> Sent: Tuesday, May 19, 2020 4:49 PM
> To: Mukunda, Vijendar <Vijendar.Mukunda@amd.com>
> Cc: alsa-devel@alsa-project.org; tiwai@suse.de; Deucher, Alexander
> <Alexander.Deucher@amd.com>
> Subject: Re: [PATCH v3 08/14] ASoC: amd: add ACP PDM DMA driver dai ops
> 
> On Tue, May 19, 2020 at 01:16:58AM +0800, Vijendar Mukunda wrote:
> 
> > +static int acp_pdm_dai_hw_params(struct snd_pcm_substream *substream,
> > +				 struct snd_pcm_hw_params *params,
> > +				 struct snd_soc_dai *dai)
> > +{
> > +	struct pdm_stream_instance *rtd;
> > +	unsigned int ch_mask;
> > +
> > +	rtd = substream->runtime->private_data;
> > +	switch (params_channels(params)) {
> > +	case TWO_CH:
> > +	default:
> > +		ch_mask = 0x00;
> > +		break;
> > +	}
> 
> The TWO_CH define isn't adding anything, and I'd expect there to be
> invalid channel configurations this is rejecting - at the minute this
> just boils down to an assignment.

Currently we have added two channel support. 
As of today, as we restricted no of channels to 2 , there is no point 
to check invalid configuration.
It kept for future expansion to support more than two channels.

> 
> > +	config_pdm_stream_params(ch_mask, rtd->acp_base);
> 
> Does this function have any other callers - is there a need for it to be
> a separate function?
Current ask is only to support 48Khz, 2 Channel streams.
This is kept for future reference.
This API works as place holder to expand the logic to support multiple
sample rates and no of channels.
Even we can discard this API , do in it calling API itself.