Re: [alsa-devel] [PATCH linux-next v2 9/9] ASoC: rsnd: add busif property to dai stream

[Jiada Wang]

Hi Morimoto-san


On 2018/10/04 10:41, Kuninori Morimoto wrote:
> Hi Jiada
>
> Thank you for your patch
>
> > in GEN3 SSI may use different BUSIF for data transfer,
> > this patch adds busif property to each dai stream,
> > to indicate the BUSIF used by playback/capture stream.
> >
> > Also adds rsnd_ssi_select_busif() to automatically select
> > BUSIF (currently only BUSIF0 is selected)
> >
> > Signed-off-by: Jiada Wang <jiada_wang@xxxxxxxxxx>
> > ---
> >   sound/soc/sh/rcar/core.c |  3 +++
> >   sound/soc/sh/rcar/dma.c  | 31 +++++++++++++++++++++++++++++++
> >   sound/soc/sh/rcar/rsnd.h |  3 +++
> >   sound/soc/sh/rcar/ssi.c  | 30 +++++++++++++++++++++++++++++-
> >   4 files changed, 66 insertions(+), 1 deletion(-)
> >
> > diff --git a/sound/soc/sh/rcar/core.c b/sound/soc/sh/rcar/core.c
> > index 40d7dc4f7839..5e3e6e65bcdf 100644
> > --- a/sound/soc/sh/rcar/core.c
> > +++ b/sound/soc/sh/rcar/core.c
> > @@ -1158,6 +1158,9 @@ static int rsnd_hw_params(struct snd_pcm_substream *substream,
> >   	struct rsnd_dai *rdai = rsnd_dai_to_rdai(dai);
> >   	struct rsnd_dai_stream *io = rsnd_rdai_to_io(rdai, substream);
> >   	int ret;
> > +	int chan = rsnd_runtime_channel_for_ssi_with_params(io, hw_params);
> > +
> > +	rsnd_ssi_select_busif(io, chan);
> If my understanding was correct, the chance to use BUSIFx is when TDM split mode.
Yes, only when SSI works in Split/Ex-Split mode, BUSIFx other than 0 is 
necessary
> And this patch selects it on runtime (= hw_param) ?
Because, in order to automatically determine BUSIF number,
information like SSI mode (non-Split/Split/Ex-Split), runtime channel, 
are required
(in our internal implementation, SSI mode is selected by kctrl)
because of this, in this patch, BUSIF is selected on runtime

> But, I think we can/should select it on probe timing from DT connection.
> Am I misunderstanding ?
with the above reasoning, BUSIF is selected on runtime.
what do you think?

Thanks,
Jiada
> I'm not sure how to select, but adding new ssiuX0 - ssiuX7
> is realistic idea (parse sound card is not realistic...) ?
> If so, your rxu/txu DMA can be more simple ?