[alsa-devel] [PATCH 01/19] ASoC: atmel: Don't set unused struct snd_pcm_hardware fields

[Bo Shen]

Hi Lars,

On 01/05/2014 02:15 AM, Lars-Peter Clausen wrote:
> On 12/20/2013 02:20 PM, Lars-Peter Clausen wrote:
>> The ASoC core assumes that the PCM component of the ASoC card transparently
>> moves data around and does not impose any restrictions on the memory layout or
>> the transfer speed. It ignores all fields from the snd_pcm_hardware struct for
>> the PCM driver that are related to this. Setting these fields in the PCM driver
>> might suggest otherwise though, so rather not set them.
>>
>> Signed-off-by: Lars-Peter Clausen <lars at metafoo.de>
>> Cc: Bo Shen <voice.shen at atmel.com>
>> Cc: Nicolas Ferre <nicolas.ferre at atmel.com>
>> ---
>>   sound/soc/atmel/atmel-pcm-dma.c | 1 -
>>   sound/soc/atmel/atmel-pcm-pdc.c | 1 -
>>   2 files changed, 2 deletions(-)
>>
>> diff --git a/sound/soc/atmel/atmel-pcm-dma.c b/sound/soc/atmel/atmel-pcm-dma.c
>> index 06082e5..b79a2a8 100644
>> --- a/sound/soc/atmel/atmel-pcm-dma.c
>> +++ b/sound/soc/atmel/atmel-pcm-dma.c
>> @@ -50,7 +50,6 @@ static const struct snd_pcm_hardware atmel_pcm_dma_hardware = {
>>   				  SNDRV_PCM_INFO_INTERLEAVED |
>>   				  SNDRV_PCM_INFO_RESUME |
>>   				  SNDRV_PCM_INFO_PAUSE,
>> -	.formats		= SNDRV_PCM_FMTBIT_S16_LE,
>
> Atmel is one of the few platforms where the formats specified for the DMA
> controller are more restrictive than the formats specified for the DAI. As
> the restrictions specified by the PCM part have been ignored so far I'm
> wondering if this is a real restriction and things have only worked by
> chance or whether the restriction should be removed?

This is not a real restriction for DMA, this can be removed. Only the 
SSC have the restriction, and we check it in DAI driver.

For this patch,
Acked-by: Bo Shen <voice.shen at atmel.com>

> - Lars
>

Best Regards,
Bo Shen