RE: [PATCH -next] ASoC: sh: rz-ssi: Fix return value check in rz_ssi_dma_request()

[Biju Das <biju.das.jz@bp.renesas.com>]

Hi Yang Yingliang,

Still some improvements to be done on this patch.
If one of the dma channel is failed, we should fallback that channel to PIO.

Something like below. I will post a new patch after testing this.

ssi->playback.transfer = rz_ssi_pio_send;
ssi->capture.transfer = rz_ssi_pio_recv;

/* Detect DMA support */
ret = rz_ssi_dma_request(ssi, &pdev->dev);
if (ret < 0) {
	dev_warn(&pdev->dev, "DMA not available, using PIO\n");
} else {
	dev_info(&pdev->dev, "DMA enabled");
	if (ssi->playback.dma_ch)
		ssi->playback.transfer = rz_ssi_dma_transfer;
	if (ssi->capture.dma_ch)
		ssi->capture.transfer = rz_ssi_dma_transfer;
}

Regards,
Biju


> Subject: RE: [PATCH -next] ASoC: sh: rz-ssi: Fix return value check in
> rz_ssi_dma_request()
> 
> Hi Yang Yingliang,
> 
> Thanks for your patch.
> 
> Already I have posted a patch for fixing it.
> 
> https://patchwork.kernel.org/project/alsa-
> devel/patch/20210814180120.18082-1-biju.das.jz@bp.renesas.com/
> 
> Since you posted a similar patch as Reported-by: Hulk Robot
> <hulkci@huawei.com>, I am adding my Rb tag for this patch.
> 
> Regards,
> Biju
> 
> 
> > -----Original Message-----
> > From: Yang Yingliang <yangyingliang@huawei.com>
> > Sent: 17 August 2021 04:00
> > To: linux-kernel@vger.kernel.org; alsa-devel@alsa-project.org
> > Cc: broonie@kernel.org; Biju Das <biju.das.jz@bp.renesas.com>;
> > Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@bp.renesas.com>;
> > lgirdwood@gmail.com
> > Subject: [PATCH -next] ASoC: sh: rz-ssi: Fix return value check in
> > rz_ssi_dma_request()
> >
> > In case of error, the function dma_request_chan() returns ERR_PTR()
> > and never returns NULL. Set 'dma_ch' to NULL, if dma_request_chan()
> > returns error, so the code using 'dma_ch' can work correctly.
> >
> > Fixes: 26ac471c5354 ("ASoC: sh: rz-ssi: Add SSI DMAC support")
> > Reported-by: Hulk Robot <hulkci@huawei.com>
> > Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
> 
> Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
> 
> > ---
> >  sound/soc/sh/rz-ssi.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/sound/soc/sh/rz-ssi.c b/sound/soc/sh/rz-ssi.c index
> > ea8d33ede5d2..5ec78fd94d94 100644
> > --- a/sound/soc/sh/rz-ssi.c
> > +++ b/sound/soc/sh/rz-ssi.c
> > @@ -676,11 +676,17 @@ static void rz_ssi_release_dma_channels(struct
> > rz_ssi_priv *ssi)  static int rz_ssi_dma_request(struct rz_ssi_priv
> > *ssi, struct device *dev)  {
> >  	ssi->playback.dma_ch = dma_request_chan(dev, "tx");
> > +	if (IS_ERR(ssi->playback.dma_ch))
> > +		ssi->playback.dma_ch = NULL;
> >  	ssi->capture.dma_ch = dma_request_chan(dev, "rx");
> > +	if (IS_ERR(ssi->capture.dma_ch))
> > +		ssi->capture.dma_ch = NULL;
> >  	if (!ssi->playback.dma_ch && !ssi->capture.dma_ch) {
> >  		ssi->playback.dma_ch = dma_request_chan(dev, "rt");
> > -		if (!ssi->playback.dma_ch)
> > +		if (IS_ERR(ssi->playback.dma_ch)) {
> > +			ssi->playback.dma_ch = NULL;
> >  			goto no_dma;
> > +		}
> >
> >  		ssi->dma_rt = true;
> >  	}
> > --
> > 2.25.1