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

Frank Li
2026-01-29T17:10:11Z

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.

> + 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?

> + 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.

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
>