On Fri, Sep 6, 2019 at 4:25 AM Nicolin Chen nicoleotsuka@gmail.com wrote:
On Fri, Aug 30, 2019 at 11:09:00PM +0300, Daniel Baluta wrote:
From: Mihai Serban mihai.serban@nxp.com
EDMA requires the period size to be multiple of maxburst. Otherwise the remaining bytes are not transferred and thus noise is produced.
We can handle this issue by adding a constraint on SNDRV_PCM_HW_PARAM_PERIOD_SIZE to be multiple of tx/rx maxburst value.
Cc: NXP Linux Team linux-imx@nxp.com Signed-off-by: Mihai Serban mihai.serban@nxp.com Signed-off-by: Daniel Baluta daniel.baluta@nxp.com
sound/soc/fsl/fsl_sai.c | 15 +++++++++++++++ sound/soc/fsl/fsl_sai.h | 1 + 2 files changed, 16 insertions(+)
diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c index 728307acab90..fe126029f4e3 100644 --- a/sound/soc/fsl/fsl_sai.c +++ b/sound/soc/fsl/fsl_sai.c @@ -612,6 +612,16 @@ static int fsl_sai_startup(struct snd_pcm_substream *substream, FSL_SAI_CR3_TRCE_MASK, FSL_SAI_CR3_TRCE);
/** some DMA controllers need period size to be a multiple of* tx/rx maxburst*/if (sai->soc_data->use_constraint_period_size)snd_pcm_hw_constraint_step(substream->runtime, 0,SNDRV_PCM_HW_PARAM_PERIOD_SIZE,tx ? sai->dma_params_tx.maxburst :sai->dma_params_rx.maxburst);I feel that PERIOD_SIZE could be used for some other cases than being related to maxburst....
static const struct of_device_id fsl_sai_ids[] = { diff --git a/sound/soc/fsl/fsl_sai.h b/sound/soc/fsl/fsl_sai.h index b89b0ca26053..3a3f6f8e5595 100644 --- a/sound/soc/fsl/fsl_sai.h +++ b/sound/soc/fsl/fsl_sai.h @@ -157,6 +157,7 @@
struct fsl_sai_soc_data { bool use_imx_pcm;
bool use_constraint_period_size;....so maybe the soc specific flag here could be something like bool use_edma;
What do you think?
I think your suggestion is a little bit better than what we have. But what if in the future another DMA controler (not eDMA) will need the same constraint.
Wouldn't it be confusing?