> -----Original Message-----
> From: Alsa-devel <alsa-devel-bounces@xxxxxxxxxxxxxxxx> On
> Behalf Of Sit, Michael Wei Hong
> Sent: Tuesday, 15 December, 2020 6:15 PM
> To: Lars-Peter Clausen <lars@xxxxxxxxxx>; alsa-devel@alsa-
> project.org
> Cc: Rojewski, Cezary <cezary.rojewski@xxxxxxxxx>;
> tiwai@xxxxxxxx; Sia, Jee Heng <jee.heng.sia@xxxxxxxxx>; pierre-
> louis.bossart@xxxxxxxxxxxxxxx; liam.r.girdwood@xxxxxxxxxxxxxxx;
> broonie@xxxxxxxxxx
> Subject: RE: [PATCH 2/2] ASoC: Intel: KMB: Enable DMA transfer
> mode
>
>
>
> > -----Original Message-----
> > From: Lars-Peter Clausen <lars@xxxxxxxxxx>
> > Sent: Tuesday, 15 December, 2020 5:41 PM
> > To: Sit, Michael Wei Hong <michael.wei.hong.sit@xxxxxxxxx>;
> > alsa-devel@xxxxxxxxxxxxxxxx
> > Cc: Rojewski, Cezary <cezary.rojewski@xxxxxxxxx>;
> tiwai@xxxxxxxx; Sia,
> > Jee Heng <jee.heng.sia@xxxxxxxxx>; pierre-
> > louis.bossart@xxxxxxxxxxxxxxx; liam.r.girdwood@xxxxxxxxxxxxxxx;
> > broonie@xxxxxxxxxx
> > Subject: Re: [PATCH 2/2] ASoC: Intel: KMB: Enable DMA
> transfer mode
> >
> > On 12/15/20 6:33 AM, Michael Sit Wei Hong wrote:
> > > [...]
> > > +static inline void kmb_i2s_enable_dma(struct kmb_i2s_info
> > *kmb_i2s,
> > > +u32 stream) {
> > > + u32 dma_reg;
> > > +
> > > + dma_reg = readl(kmb_i2s->i2s_base + I2S_DMACR);
> > > + /* Enable DMA handshake for stream */
> > > + if (stream == SNDRV_PCM_STREAM_PLAYBACK)
> > > + dma_reg |= I2S_DMAEN_TXBLOCK;
> > > + else
> > > + dma_reg |= I2S_DMAEN_RXBLOCK;
> > > +
> > > + writel(dma_reg, kmb_i2s->i2s_base + I2S_DMACR); }
> > > +
> > > +static inline void kmb_i2s_disable_dma(struct kmb_i2s_info
> > *kmb_i2s,
> > > +u32 stream) {
> > > + u32 dma_reg;
> > > +
> > > + dma_reg = readl(kmb_i2s->i2s_base + I2S_DMACR);
> > > + /* Disable DMA handshake for stream */
> > > + if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
> > > + dma_reg &= ~I2S_DMAEN_TXBLOCK;
> > > + writel(1, kmb_i2s->i2s_base + I2S_RTXDMA);
> > > + } else {
> > > + dma_reg &= ~I2S_DMAEN_RXBLOCK;
> > > + writel(1, kmb_i2s->i2s_base + I2S_RRXDMA);
> > > + }
> > > + writel(dma_reg, kmb_i2s->i2s_base + I2S_DMACR);
> >
> > Does this need locking? I believe it is possible for the startup
> > callback of the playback and capture stream to be called
> concurrently.
> >
> Pierre did raised this concern previously and checked that the
> upper layers has already a locking mechanism in place before this
> is called.
> If we look at the uses of snd_soc_dai_startup() and
> snd_soc_dai_shutdown(), they are all protected by
> mutex_lock_nested(&rtd->card->pcm_mutex, rtd->card-
> >pcm_subclass);
> > > +}
> > > +
> > > static void kmb_i2s_start(struct kmb_i2s_info *kmb_i2s,
> > > struct snd_pcm_substream *substream)
> > > {
> > > @@ -356,7 +405,11 @@ static void kmb_i2s_start(struct
> > kmb_i2s_info *kmb_i2s,
> > > else
> > > writel(1, kmb_i2s->i2s_base + IRER);
> > >
> > > - kmb_i2s_irq_trigger(kmb_i2s, substream->stream,
> > config->chan_nr, true);
> > > + if (kmb_i2s->use_pio)
> > > + kmb_i2s_irq_trigger(kmb_i2s, substream-
> > >stream,
> > > + config->chan_nr, true);
> > > + else
> > > + kmb_i2s_enable_dma(kmb_i2s, substream-
> > >stream);
> > >
> > > if (kmb_i2s->master)
> > > writel(1, kmb_i2s->i2s_base + CER);
> > [...]
Any further comments on this patch set?
