[alsa-devel] Exporting playback and capture capability to user space

[Rajeev kumar]

Hello Mark

On 1/9/2012 12:01 PM, Rajeev kumar wrote:
> On 12/2/2011 4:20 PM, Rajeev kumar wrote:
>> Hello Vinod,
>>
>> On 11/22/2011 9:57 AM, Rajeev kumar wrote:
>>> Hello Vinod, Mark
>>>
>>>
>>> On 11/21/2011 11:53 AM, Vinod Koul wrote:
>>>> On Mon, 2011-11-21 at 11:19 +0530, Rajeev kumar wrote:
>>>>> Hello Mark
>>>>>
>>>>> Could you please help me by answering these questions?
>>>>>
>>>>> Best Regards
>>>>> Rajeev
>>>>>
>>>> Pls don't top-post!!
>>>>> On 11/17/2011 7:05 PM, Rajeev kumar wrote:
>>>>>> Hello Mark
>>>>>>
>>>>>> I have a single codec with playback and capture capability. We are
>>>>>> using
>>>>>> it for different i2s controller. Below are the details for that.
>>>>>>
>>>>>> case 1: I2S controller-1: with playback and capture capability
>>>>>> case 2: I2S controller-2: with playback capability only
>>>>>> case 3: I2S controller-3: with capture capability only.
>>>>>>
>>>>>> We are registering all the I2S controller with there respective
>>>>>> capability.
>>>>>>
>>>>>> In command 'aplay -l' or 'cat /proc/asound/pcm', among playback
>>>>>> devices,
>>>>>> capture device is also listed. This is true in case-1 but for case-2
>>>>>> and
>>>>>> case-3 also it is showing the same behavior. According to my
>>>>>> understanding it should not show the list of all devices i.e. in
>>>>>> case of
>>>>>> controller having playback capability it should show only playback
>>>>>> devices not capture devices and vice versa. Please correct me if I am
>>>>>> wrong.
>>>>>>
>>>>>> So my questions are
>>>>>> 1. How to separate playback and capture devices in case-2 and case-3.
>>>>>> Are we need to register different codec for different i2s controller?
>>>> How asoc builds this is based on dailinks you have provided. If for the
>>>> device 2 and device 3 the cpu and codec dais support both playback and
>>>> capture devices, it will go ahead and register these device.
>>>> The fact that for device 2 and device 3 capture is also registered
>>>> suggests me that your cpu dais are not correct.
>>>>
>>>> Would help if you post your code, esp the codec, cpu dais and dialinks.
>>>>
>>>
>>> Codec dai:
>>>
>>> static struct snd_soc_dai_driver sta529_dai = {
>>> .name = "sta529-audio",
>>> .playback = {
>>> .stream_name = "Playback",
>>> .channels_min = 2,
>>> .channels_max = 2,
>>> .rates = SPEAR_PCM_RATES,
>>> .formats = SPEAR_PCM_FORMAT,
>>> },
>>> .capture = {
>>> .stream_name = "Capture",
>>> .channels_min = 2,
>>> .channels_max = 2,
>>> .rates = SPEAR_PCM_RATES,
>>> .formats = SPEAR_PCM_FORMAT,
>>> },
>>> .ops = &sta529_dai_ops,
>>> };
>>>
>>> cpu dai: In case of cpu dai, we are passing the playback and capture
>>> capability from the platform code and depending on the capability we are
>>> filling the cpu dai structure in probe function, like
>>>
>>> if (cap & PLAY) {
>>>
>>> /* Fill Playback capability */
>>> }
>>>
>>> if (cap & RECORD) {
>>> /* Fill Capture capability */
>>> }
>>>
>>> dai links:
>>>
>>> static struct snd_soc_dai_link spear_evb_dai[] = {
>>> {
>>> .name = "sta529-pcm0",
>>> .stream_name = "I2S Playback",
>>> .cpu_dai_name = "designware-i2s.0",
>>> .platform_name = "spear-pcm-audio",
>>> .codec_dai_name = "sta529-audio",
>>> .codec_name = "sta529-codec.0-001a",
>>> .ops = &sta529_ops,
>>> }, {
>>> .name = "sta529-pcm1",
>>> .stream_name = "I2S Capture",
>>> .cpu_dai_name = "designware-i2s.1",
>>> .platform_name = "spear-pcm-audio",
>>> .codec_dai_name = "sta529-audio",
>>> .codec_name = "sta529-codec.0-001a",
>>> .ops = &sta529_ops,
>>> },
>>> };
>>>
>>> static struct snd_soc_card spear_snd_card = {
>>> .name = "spear-evb",
>>> .dai_link = spear_evb_dai,
>>> .num_links = ARRAY_SIZE(spear_evb_dai),
>>> };
>>>
>>
>> I had actually missed the last mail by mark. I dont know why? . So sorry
>> for replying on the top of this mail.
>>
>> Vinod, have you gone through the cpu_dai, codec_dai and dailink ? Could
>> you please make any suggestion?
>>
>
> Ping
>

The o/p of the cat /proc/asound/pcm does not depends on the &ing of the 
capability of i2s controller and codec. I was going through the 
soc-core.c and it seems that the capability exposed to user space only 
depends on the codec. If codec has both playback and capture capability 
,then in user space both will be exported and hence cat /proc/asound/pcm 
will show two different devices one for playback and other for capture. 
In case codec has only playback capability, the o/p of the cat 
/proc/asound/pcm will contain only playback device.

So in case of three different i2s controller with different capability, 
separate codec are required.

Please correct me if I am wrong.

Best Regards
Rajeev

>> Best Regards
>> ~Rajeev
>>
>>
>>
>>> Best Regards
>>> ~Rajeev
>>
>