Re: [PATCH 2/3] ASoC: fsl_asrc: Add support for i.MX952 platform

Frank Li
2026-01-29T17:14:42Z

On Wed, Jan 28, 2026 at 03:18:52PM +0800, Shengjiu Wang wrote:
> Add a compatible string and clock mapping table to support ASRC on the
> i.MX952 platform.
>
> There is a limitation on i.MX952 that dma request is not cleared at the
> end of conversion with dma slave mode. Which causes sample is dropped
> from the input fifo on the second time if dma is triggered before the
> client device and EDMA may copy wrong data from output fifo as the output
> fifo is not ready in the beginning.
>
> So need to trigger asrc before dma on i.MX952, and add delay to wait
> output data is generated then start the EDMA for output, otherwise the
> m2m function has noise issues.
>
> Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
> ---
> sound/soc/fsl/fsl_asrc.c | 39 +++++++++++++++++++++++++++++++++
> sound/soc/fsl/fsl_asrc.h | 16 ++++++++++++++
> sound/soc/fsl/fsl_asrc_common.h | 3 +++
> sound/soc/fsl/fsl_asrc_m2m.c | 29 +++++++++++++++++-------
> 4 files changed, 79 insertions(+), 8 deletions(-)
>
...
> diff --git a/sound/soc/fsl/fsl_asrc_m2m.c b/sound/soc/fsl/fsl_asrc_m2m.c
> index f46881f71e43..296e13a16490 100644
> --- a/sound/soc/fsl/fsl_asrc_m2m.c
> +++ b/sound/soc/fsl/fsl_asrc_m2m.c
> @@ -253,15 +253,28 @@ static int asrc_m2m_device_run(struct fsl_asrc_pair *pair, struct snd_compr_task
> reinit_completion(&pair->complete[IN]);
> reinit_completion(&pair->complete[OUT]);
>
> - /* Submit DMA request */
> - dmaengine_submit(pair->desc[IN]);
> - dma_async_issue_pending(pair->desc[IN]->chan);
> - if (out_dma_len > 0) {
> - dmaengine_submit(pair->desc[OUT]);
> - dma_async_issue_pending(pair->desc[OUT]->chan);
> - }
> + if (asrc->start_before_dma) {
> + asrc->m2m_start(pair);

Does other Soc also work if ASRC start before DMA enable? Suppose most like
work. Then needn't start_before_dma.

Frank

> + /* Submit DMA request */
> + dmaengine_submit(pair->desc[IN]);
> + dma_async_issue_pending(pair->desc[IN]->chan);
> + if (out_dma_len > 0) {
> + if (asrc->m2m_output_ready)
> + asrc->m2m_output_ready(pair);
> + dmaengine_submit(pair->desc[OUT]);
> + dma_async_issue_pending(pair->desc[OUT]->chan);
> + }
> + } else {
> + /* Submit DMA request */
> + dmaengine_submit(pair->desc[IN]);
> + dma_async_issue_pending(pair->desc[IN]->chan);
> + if (out_dma_len > 0) {
> + dmaengine_submit(pair->desc[OUT]);
> + dma_async_issue_pending(pair->desc[OUT]->chan);
> + }
>
> - asrc->m2m_start(pair);
> + asrc->m2m_start(pair);
> + }
>
> if (!wait_for_completion_interruptible_timeout(&pair->complete[IN], 10 * HZ)) {
> dev_err(dev, "out DMA task timeout\n");
> --
> 2.34.1
>