Re: [PATCH 3/3] ASoC: fsl_asrc_dma: allocate memory from dma device

Shengjiu Wang
2026-01-30T01:52:44Z

On Fri, Jan 30, 2026 at 1:09 AM Frank Li <Frank.li@nxp.com> wrote:
>
> On Wed, Jan 28, 2026 at 03:18:53PM +0800, Shengjiu Wang wrote:
> > As the dma device may support dma-coherent property on the i.MX952,
> > allocate memory from dma device to make asrc driver to be compatible with
> > such a case.
> >
> > Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
> > ---
> > sound/soc/fsl/fsl_asrc_dma.c | 48 ++++++++++++++++++++++++++++++------
> > 1 file changed, 41 insertions(+), 7 deletions(-)
> >
> > diff --git a/sound/soc/fsl/fsl_asrc_dma.c b/sound/soc/fsl/fsl_asrc_dma.c
> > index 7dacc06b2f02..b8fe242d53db 100644
> > --- a/sound/soc/fsl/fsl_asrc_dma.c
> > +++ b/sound/soc/fsl/fsl_asrc_dma.c
> > @@ -449,18 +449,52 @@ fsl_asrc_dma_pcm_pointer(struct snd_soc_component *component,
> > static int fsl_asrc_dma_pcm_new(struct snd_soc_component *component,
> > struct snd_soc_pcm_runtime *rtd)
> > {
> > - struct snd_card *card = rtd->card->snd_card;
> > + struct device *dev = component->dev;
> > + struct fsl_asrc *asrc = dev_get_drvdata(dev);
> > + struct fsl_asrc_pair *pair;
> > struct snd_pcm *pcm = rtd->pcm;
> > + struct dma_chan *chan;
> > int ret;
> >
> > - ret = dma_coerce_mask_and_coherent(card->dev, DMA_BIT_MASK(32));
> > - if (ret) {
> > - dev_err(card->dev, "failed to set DMA mask\n");
> > - return ret;
> > + pair = kzalloc(sizeof(*pair) + asrc->pair_priv_size, GFP_KERNEL);
>
> prefer use size_add(sizeof(*pair), asrc->pair_priv_size), which did
> overflow check.

Ok, will update it.

>
> > + if (!pair)
> > + return -ENOMEM;
> > +
> > + pair->asrc = asrc;
> > + pair->private = (void *)pair + sizeof(struct fsl_asrc_pair);
> > +
> > + /* Request a dummy pair, which will be released later.
> > + * Request pair function needs channel num as input, for this
> > + * dummy pair, we just request "1" channel temporarily.
> > + */
> > + ret = asrc->request_pair(1, pair);
> > + if (ret < 0) {
> > + dev_err(dev, "failed to request asrc pair\n");
> > + goto req_pair_err;
> > }
> >
> > - return snd_pcm_set_fixed_buffer_all(pcm, SNDRV_DMA_TYPE_DEV,
> > - card->dev, FSL_ASRC_DMABUF_SIZE);
> > + /* Request a dummy dma channel, which will be released later. */
> > + chan = asrc->get_dma_channel(pair, IN);
>
> Is it possible get real dma chan from fsl_asrc?

This is real dma chan, may be I should remove "dummy".

>
> > + if (!chan) {
> > + dev_err(dev, "failed to get dma channel\n");
> > + ret = -EINVAL;
> > + goto dma_chan_err;
> > + }
> > +
> > + ret = snd_pcm_set_fixed_buffer_all(pcm,
> > + SNDRV_DMA_TYPE_DEV,
> > + chan->device->dev,
> > + FSL_ASRC_DMABUF_SIZE);
>
> Here you assume chan->device->dev never change when it did DMA transfer.

Yes, this refers to the generic code in ALSA.

best regards
Shengjiu Wang

>
> Frank
> > +
> > + dma_release_channel(chan);
> > +
> > +dma_chan_err:
> > + asrc->release_pair(pair);
> > +
> > +req_pair_err:
> > + kfree(pair);
> > +
> > + return ret;
> > }
> >
> > struct snd_soc_component_driver fsl_asrc_component = {
> > --
> > 2.34.1
> >