From: Nicolin Chen <nicoleotsuka@gmail.com>
To: Daniel Baluta <daniel.baluta@gmail.com>
Cc: Linux-ALSA <alsa-devel@alsa-project.org>,
Timur Tabi <timur@kernel.org>, Xiubo Li <Xiubo.Lee@gmail.com>,
Fabio Estevam <festevam@gmail.com>,
"S.j. Wang" <shengjiu.wang@nxp.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Mark Brown <broonie@kernel.org>,
NXP Linux Team <linux-imx@nxp.com>,
Mihai Serban <mihai.serban@nxp.com>,
Daniel Baluta <daniel.baluta@nxp.com>,
Mihai Serban <mihai.serban@gmail.com>
Subject: Re: [alsa-devel] [PATCH] ASoC: fsl_sai: Fix noise when using EDMA
Date: Mon, 9 Sep 2019 12:32:38 -0700 [thread overview]
Message-ID: <20190909193238.GA10344@Asurada-Nvidia.nvidia.com> (raw)
In-Reply-To: <CAEnQRZBTc=beU7CX747RsM7KEsJethfZ0fPv=CkLQ1e3ofHMkA@mail.gmail.com>
On Fri, Sep 06, 2019 at 09:46:12AM +0300, Daniel Baluta wrote:
> On Fri, Sep 6, 2019 at 4:25 AM Nicolin Chen <nicoleotsuka@gmail.com> wrote:
> >
> > On Fri, Aug 30, 2019 at 11:09:00PM +0300, Daniel Baluta wrote:
> > > From: Mihai Serban <mihai.serban@nxp.com>
> > >
> > > EDMA requires the period size to be multiple of maxburst. Otherwise the
> > > remaining bytes are not transferred and thus noise is produced.
> > >
> > > We can handle this issue by adding a constraint on
> > > SNDRV_PCM_HW_PARAM_PERIOD_SIZE to be multiple of tx/rx maxburst value.
> > >
> > > Cc: NXP Linux Team <linux-imx@nxp.com>
> > > Signed-off-by: Mihai Serban <mihai.serban@nxp.com>
> > > Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
> > > ---
> > > sound/soc/fsl/fsl_sai.c | 15 +++++++++++++++
> > > sound/soc/fsl/fsl_sai.h | 1 +
> > > 2 files changed, 16 insertions(+)
> > >
> > > diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
> > > index 728307acab90..fe126029f4e3 100644
> > > --- a/sound/soc/fsl/fsl_sai.c
> > > +++ b/sound/soc/fsl/fsl_sai.c
> > > @@ -612,6 +612,16 @@ static int fsl_sai_startup(struct snd_pcm_substream *substream,
> > > FSL_SAI_CR3_TRCE_MASK,
> > > FSL_SAI_CR3_TRCE);
> > >
> > > + /*
> > > + * some DMA controllers need period size to be a multiple of
> > > + * tx/rx maxburst
> > > + */
> > > + if (sai->soc_data->use_constraint_period_size)
> > > + snd_pcm_hw_constraint_step(substream->runtime, 0,:
> > > + SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
> > > + tx ? sai->dma_params_tx.maxburst :
> > > + sai->dma_params_rx.maxburst);
> >
> > I feel that PERIOD_SIZE could be used for some other cases than
> > being related to maxburst....
> >
> > > static const struct of_device_id fsl_sai_ids[] = {
> > > diff --git a/sound/soc/fsl/fsl_sai.h b/sound/soc/fsl/fsl_sai.h
> > > index b89b0ca26053..3a3f6f8e5595 100644
> > > --- a/sound/soc/fsl/fsl_sai.h
> > > +++ b/sound/soc/fsl/fsl_sai.h
> > > @@ -157,6 +157,7 @@
> > >
> > > struct fsl_sai_soc_data {
> > > bool use_imx_pcm;
> > > + bool use_constraint_period_size;
> >
> > ....so maybe the soc specific flag here could be something like
> > bool use_edma;
> >
> > What do you think?
>
> I think your suggestion is a little bit better than what we have. But what if
The better part of using "edma" word, I felt, is to match this
"soc" word in the structure name.
> in the future another DMA controler (not eDMA) will need the same constraint.
That sounds like a valid point to me, I don't feel it'd happen
that often though. I'd be okay if you insist to keep yours :)
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prev parent reply other threads:[~2019-09-09 19:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-30 20:09 [PATCH] ASoC: fsl_sai: Fix noise when using EDMA Daniel Baluta
2019-08-30 20:09 ` [alsa-devel] " Daniel Baluta
2019-09-06 1:24 ` Nicolin Chen
2019-09-06 6:46 ` Daniel Baluta
2019-09-09 19:32 ` Nicolin Chen [this message]
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