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); + ret = snd_pcm_hw_constraint_list(substream->runtime, 0, SNDRV_PCM_HW_PARAM_RATE, &fsl_sai_rate_constraints);
@@ -1011,30 +1021,35 @@ static const struct fsl_sai_soc_data fsl_sai_vf610_data = { .use_imx_pcm = false, .fifo_depth = 32, .reg_offset = 0, + .use_constraint_period_size = false, };
static const struct fsl_sai_soc_data fsl_sai_imx6sx_data = { .use_imx_pcm = true, .fifo_depth = 32, .reg_offset = 0, + .use_constraint_period_size = false, };
static const struct fsl_sai_soc_data fsl_sai_imx7ulp_data = { .use_imx_pcm = true, .fifo_depth = 16, .reg_offset = 8, + .use_constraint_period_size = false, };
static const struct fsl_sai_soc_data fsl_sai_imx8mq_data = { .use_imx_pcm = true, .fifo_depth = 128, .reg_offset = 8, + .use_constraint_period_size = false, };
static const struct fsl_sai_soc_data fsl_sai_imx8qm_data = { .use_imx_pcm = true, .fifo_depth = 64, .reg_offset = 0, + .use_constraint_period_size = true, };
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; unsigned int fifo_depth; unsigned int reg_offset; };