[alsa-devel] [RFC] ASoC: soc-pcm: Add support for unidirectional dai links

[Lars-Peter Clausen]

On 08/29/2013 12:47 PM, Mark Brown wrote:
> On Thu, Aug 29, 2013 at 01:54:59AM -0300, Fabio Estevam wrote:
> 
>> @@ -105,11 +105,13 @@ static struct snd_soc_dai_link mxs_sgtl5000_dai[] = {
>>  		.stream_name	= "HiFi Playback",
>>  		.codec_dai_name	= "sgtl5000",
>>  		.ops		= &mxs_sgtl5000_hifi_ops,
>> +		.playback_only	= true,
>>  	}, {
>>  		.name		= "HiFi Rx",
>>  		.stream_name	= "HiFi Capture",
>>  		.codec_dai_name	= "sgtl5000",
>>  		.ops		= &mxs_sgtl5000_hifi_ops,
>> +		.capture_only	= true,
>>  	},
> 
> This doesn't make much sense to me - it should be possible to tell from
> the capabilities of the two DAIs on the link if they support both
> playback and capture.  Or has the board wired up two bidirectional DAIs
> on each link for some reason?
> 

The MXS DAIs are unidirectional, but the direction can be configured at
runtime. The alternative here is to specify the direction at driver probe
time instead of in the dai_link.