[alsa-devel] [EXT] Re: [PATCH 3/3] ASoC: fsl_asrc: Fix error with S24_3LE format bitstream in i.MX8

[S.j. Wang]

Hi

> 
> On Mon, Sep 09, 2019 at 06:33:21PM -0400, Shengjiu Wang wrote:
> > There is error "aplay: pcm_write:2023: write error: Input/output error"
> > on i.MX8QM/i.MX8QXP platform for S24_3LE format.
> >
> > In i.MX8QM/i.MX8QXP, the DMA is EDMA, which don't support 24bit
> > sample, but we didn't add any constraint, that cause issues.
> >
> > So we need to query the caps of dma, then update the hw parameters
> > according to the caps.
> 
> > @@ -285,8 +293,81 @@ static int fsl_asrc_dma_startup(struct
> > snd_pcm_substream *substream)
> >
> >       runtime->private_data = pair;
> >
> > -     snd_pcm_hw_constraint_integer(substream->runtime,
> > -                                   SNDRV_PCM_HW_PARAM_PERIODS);
> > +     ret = snd_pcm_hw_constraint_integer(substream->runtime,
> > +                                         SNDRV_PCM_HW_PARAM_PERIODS);
> > +     if (ret < 0) {
> > +             dev_err(dev, "failed to set pcm hw params periods\n");
> > +             return ret;
> > +     }
> > +
> > +     dma_data = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);
> > +
> > +     /* Request a temp pair, which is release in the end */
> > +     fsl_asrc_request_pair(1, pair);
> 
> Not sure if it'd be practical, but a pair request could fail. Will probably need
> to check return value.
> 
> And a quick feeling is that below code is mostly identical to what is in the
> soc-generic-dmaengine-pcm.c file. So I'm wondering if we could abstract a
> helper function somewhere in the ASoC core: Mark?
> 
> Thanks
> Nicolin
> 
Yes, it refers to the code in soc-generic-dmaengine-pcm.c, if there is a common
API, this is helpful.

Best regards
Wang shengjiu