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    SubjectRe: [RFC PATCH] ASoC: fsl_sai: Enable data lines based on input channels
    On Wed, Aug 14, 2019 at 4:39 AM Nicolin Chen <nicoleotsuka@gmail.com> wrote:
    >
    > On Sun, Aug 11, 2019 at 10:55:45PM +0300, Daniel Baluta wrote:
    > > An audio data frame consists of a number of slots one for each
    > > channel. In the case of I2S there are 2 data slots / frame.
    > >
    > > The maximum number of SAI slots / frame is configurable at
    > > IP integration time. This affects the width of Mask Register.
    > > SAI supports up to 32 slots per frame.
    > >
    > > The number of datalines is also configurable (up to 8 datalines)
    > > and affects TCE/RCE and the number of data/FIFO registers.
    > >
    > > The number of needed data lines (pins) is computed as follows:
    > >
    > > * pins = channels / slots.
    > >
    > > This can be computed in hw_params function so lets move TRCE bits
    > > seting from startup to hw_params.
    > >
    > > Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
    > > ---
    > > sound/soc/fsl/fsl_sai.c | 34 +++++++++++++---------------------
    > > sound/soc/fsl/fsl_sai.h | 2 +-
    > > 2 files changed, 14 insertions(+), 22 deletions(-)
    > >
    > > diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
    > > index 69cf3678c859..b70032c82fe2 100644
    > > --- a/sound/soc/fsl/fsl_sai.c
    > > +++ b/sound/soc/fsl/fsl_sai.c
    >
    > > @@ -480,13 +483,17 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
    >
    > > - regmap_write(sai->regmap, FSL_SAI_xMR(tx), ~0UL - ((1 << channels) - 1));
    > > + regmap_write(sai->regmap, FSL_SAI_xMR(tx), ~0UL - ((1 << slots) - 1));
    >
    > Would this break mono channel audio?

    Indeed, this isn't good for mono. I see in our internal tree that we
    have min(channels, slots).
    This would fix mono, let me think if this is really the right solution.

    >
    > > static int fsl_sai_dai_probe(struct snd_soc_dai *cpu_dai)
    >
    > > @@ -881,6 +872,7 @@ static int fsl_sai_probe(struct platform_device *pdev)
    > > return -ENOMEM;
    > >
    > > sai->pdev = pdev;
    > > +
    >
    > Seemly unnecessary

    Oh, ok. Will fix in next version.

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