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

Shengjiu Wang
2026-01-30T01:45:05Z

On Fri, Jan 30, 2026 at 1:14 AM Frank Li <Frank.li@nxp.com> wrote:
>
> 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.

Yes, should work. but I don't want to change the original behaviour
of other SoC.

Best regards
Shengjiu Wang
>
> 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
> >