[PATCH] ASoC: meson: Use managed DMA buffer allocation

[Lars-Peter Clausen]

On 12/18/20 5:28 PM, Jerome Brunet wrote:
> On Fri 18 Dec 2020 at 16:45, Lars-Peter Clausen <lars at metafoo.de> wrote:
>
>> Using a managed buffer will pre-allocate the buffer using
>> snd_pcm_lib_preallocate_pages() and automatically free it when the PCM is
>> destroyed.
>>
>> In addition it will call snd_pcm_lib_malloc_pages() before the driver's
>> hw_params() callback and snd_pcm_lib_free_pages() after the driver's
>> hw_free() callback.
>>
>> This slightly reduces the boilerplate code of the driver.
>>
>> Signed-off-by: Lars-Peter Clausen <lars at metafoo.de>
>> ---
>>   sound/soc/meson/aiu-fifo-i2s.c   |  1 -
>>   sound/soc/meson/aiu-fifo-spdif.c |  1 -
>>   sound/soc/meson/aiu-fifo.c       | 18 ++----------------
>>   3 files changed, 2 insertions(+), 18 deletions(-)
>>
>> diff --git a/sound/soc/meson/aiu-fifo-i2s.c b/sound/soc/meson/aiu-fifo-i2s.c
>> index d91b0d874342..2388a2d0b3a6 100644
>> --- a/sound/soc/meson/aiu-fifo-i2s.c
>> +++ b/sound/soc/meson/aiu-fifo-i2s.c
>> @@ -124,7 +124,6 @@ const struct snd_soc_dai_ops aiu_fifo_i2s_dai_ops = {
>>   	.trigger	= aiu_fifo_i2s_trigger,
>>   	.prepare	= aiu_fifo_i2s_prepare,
>>   	.hw_params	= aiu_fifo_i2s_hw_params,
>> -	.hw_free	= aiu_fifo_hw_free,
>>   	.startup	= aiu_fifo_startup,
>>   	.shutdown	= aiu_fifo_shutdown,
>>   };
>> diff --git a/sound/soc/meson/aiu-fifo-spdif.c b/sound/soc/meson/aiu-fifo-spdif.c
>> index 44eb6faacf44..2fb30f89bf7a 100644
>> --- a/sound/soc/meson/aiu-fifo-spdif.c
>> +++ b/sound/soc/meson/aiu-fifo-spdif.c
>> @@ -158,7 +158,6 @@ const struct snd_soc_dai_ops aiu_fifo_spdif_dai_ops = {
>>   	.trigger	= fifo_spdif_trigger,
>>   	.prepare	= fifo_spdif_prepare,
>>   	.hw_params	= fifo_spdif_hw_params,
>> -	.hw_free	= aiu_fifo_hw_free,
>>   	.startup	= aiu_fifo_startup,
>>   	.shutdown	= aiu_fifo_shutdown,
>>   };
>> diff --git a/sound/soc/meson/aiu-fifo.c b/sound/soc/meson/aiu-fifo.c
>> index aa88aae8e517..4ad23267cace 100644
>> --- a/sound/soc/meson/aiu-fifo.c
>> +++ b/sound/soc/meson/aiu-fifo.c
>> @@ -99,11 +99,6 @@ int aiu_fifo_hw_params(struct snd_pcm_substream *substream,
>>   	struct snd_soc_component *component = dai->component;
>>   	struct aiu_fifo *fifo = dai->playback_dma_data;
>>   	dma_addr_t end;
>> -	int ret;
>> -
>> -	ret = snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(params));
>> -	if (ret < 0)
>> -		return ret;
>>   
>>   	/* Setup the fifo boundaries */
>>   	end = runtime->dma_addr + runtime->dma_bytes - fifo->fifo_block;
>> @@ -124,12 +119,6 @@ int aiu_fifo_hw_params(struct snd_pcm_substream *substream,
>>   	return 0;
>>   }
>>   
>> -int aiu_fifo_hw_free(struct snd_pcm_substream *substream,
>> -		     struct snd_soc_dai *dai)
>> -{
>> -	return snd_pcm_lib_free_pages(substream);
>> -}
>> -
>>   static irqreturn_t aiu_fifo_isr(int irq, void *dev_id)
>>   {
>>   	struct snd_pcm_substream *playback = dev_id;
>> @@ -187,15 +176,12 @@ void aiu_fifo_shutdown(struct snd_pcm_substream *substream,
>>   int aiu_fifo_pcm_new(struct snd_soc_pcm_runtime *rtd,
>>   		     struct snd_soc_dai *dai)
>>   {
>> -	struct snd_pcm_substream *substream =
>> -		rtd->pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream;
>>   	struct snd_card *card = rtd->card->snd_card;
>>   	struct aiu_fifo *fifo = dai->playback_dma_data;
>>   	size_t size = fifo->pcm->buffer_bytes_max;
>>   
>> -	snd_pcm_lib_preallocate_pages(substream,
>> -				      SNDRV_DMA_TYPE_DEV,
>> -				      card->dev, size, size);
>> +	snd_pcm_set_managed_buffer_all(rtd->pcm, SNDRV_DMA_TYPE_DEV,
>> +				       card->dev, size, size);
> Hi Lars-Peter,
>
> These FIFOs only do playback so to avoid wasting memory
> s/snd_pcm_set_managed_buffer_all/snd_pcm_set_managed_buffer ?

snd_pcm_set_managed_buffer_all() will skip substreams that do not exist. E.g. if the there is not capture support it wont allocate memory for it.

To keep things simple I prefer snd_pcm_set_managed_buffer_all(). snd_pcm_set_managed_buffer() only makes sense if you have a different DMA device for capture and playback or you want different buffer sizes.