Re: [linux-sunxi] [PATCH v5 02/20] ASoC: sun4i-i2s: Change set_chan_cfg() params

[Clément Péron]

Hi Chen-Yu,

On Mon, 28 Sep 2020 at 07:00, Chen-Yu Tsai <wens@xxxxxxxx> wrote:
>
> On Mon, Sep 28, 2020 at 3:29 AM Clément Péron <peron.clem@xxxxxxxxx> wrote:
> >
> > As slots and slot_width can be overwritter in case set_tdm() is
> > called. Avoid to have this logic in set_chan_cfg().
>
> It doesn't seem that set_tdm_slot() would get called concurrently
> with hw_params(), at least not for the simple-card family. If so
> then we'd have more problems like mismatched slots/slot-width
> due to no serialization when interacting with those values.

Sorry maybe the commit log is not clear.
I was not talking about a concurrent effect but more if the slot_width is setted
then we don't properly use it later.

>
> > Instead pass the required values as params to set_chan_cfg().
> >
> > This will also avoid a bug when we will enable 20/24bits support,
> > i2s->slot_width is not actually used in the lrck_period computation.
> >
> > Suggested-by: Samuel Holland <samuel@xxxxxxxxxxxx>
> > Signed-off-by: Clément Péron <peron.clem@xxxxxxxxx>
> > ---
> >  sound/soc/sunxi/sun4i-i2s.c | 36 ++++++++++++++----------------------
> >  1 file changed, 14 insertions(+), 22 deletions(-)
> >
> > diff --git a/sound/soc/sunxi/sun4i-i2s.c b/sound/soc/sunxi/sun4i-i2s.c
> > index 2baf6c276280..0633b9fba3d7 100644
> > --- a/sound/soc/sunxi/sun4i-i2s.c
> > +++ b/sound/soc/sunxi/sun4i-i2s.c
> > @@ -177,8 +177,9 @@ struct sun4i_i2s_quirks {
> >         unsigned long (*get_bclk_parent_rate)(const struct sun4i_i2s *);
> >         s8      (*get_sr)(const struct sun4i_i2s *, int);
> >         s8      (*get_wss)(const struct sun4i_i2s *, int);
> > -       int     (*set_chan_cfg)(const struct sun4i_i2s *,
> > -                               const struct snd_pcm_hw_params *);
> > +       int     (*set_chan_cfg)(const struct sun4i_i2s *i2s,
> > +                               unsigned int channels,  unsigned int slots,
> > +                               unsigned int slot_width);
> >         int     (*set_fmt)(const struct sun4i_i2s *, unsigned int);
> >  };
> >
> > @@ -414,10 +415,9 @@ static s8 sun8i_i2s_get_sr_wss(const struct sun4i_i2s *i2s, int width)
> >  }
> >
> >  static int sun4i_i2s_set_chan_cfg(const struct sun4i_i2s *i2s,
> > -                                 const struct snd_pcm_hw_params *params)
> > +                                 unsigned int channels, unsigned int slots,
> > +                                 unsigned int slot_width)
> >  {
> > -       unsigned int channels = params_channels(params);
> > -
> >         /* Map the channels for playback and capture */
> >         regmap_write(i2s->regmap, SUN4I_I2S_TX_CHAN_MAP_REG, 0x76543210);
> >         regmap_write(i2s->regmap, SUN4I_I2S_RX_CHAN_MAP_REG, 0x00003210);
> > @@ -434,15 +434,11 @@ static int sun4i_i2s_set_chan_cfg(const struct sun4i_i2s *i2s,
> >  }
> >
> >  static int sun8i_i2s_set_chan_cfg(const struct sun4i_i2s *i2s,
> > -                                 const struct snd_pcm_hw_params *params)
> > +                                 unsigned int channels, unsigned int slots,
> > +                                 unsigned int slot_width)
> >  {
> > -       unsigned int channels = params_channels(params);
> > -       unsigned int slots = channels;
> >         unsigned int lrck_period;
> >
> > -       if (i2s->slots)
> > -               slots = i2s->slots;
> > -
>
> Based on the bug you highlighted in your expanded commit log, the simpler fix
> would be to look at i2s->slot_width in addition to i2s->slots, and replace
> params_physical_width(params) accordingly.

That's what I did in the first version but was pointed out by Samuel
that the same logic
was done several times. As I can avoid it by passing the correct
params it's simpler.

>
> Also, I would put fixes (even preparatory ones) before patches that introduce
> support for new features and hardware. That makes them easier to backport if
> needed.

I will wait for Maxime to comment on this. Regarding the doc fixes tag
should only be used
to fix a previous commit. This will make the fixes commit a bit more
complicated for stable kernel team.

Thanks for your review :)

Regards
Clement


>
>
> ChenYu
>
>
> >         /* Map the channels for playback and capture */
> >         regmap_write(i2s->regmap, SUN8I_I2S_TX_CHAN_MAP_REG, 0x76543210);
> >         regmap_write(i2s->regmap, SUN8I_I2S_RX_CHAN_MAP_REG, 0x76543210);
> > @@ -467,11 +463,11 @@ static int sun8i_i2s_set_chan_cfg(const struct sun4i_i2s *i2s,
> >         case SND_SOC_DAIFMT_DSP_B:
> >         case SND_SOC_DAIFMT_LEFT_J:
> >         case SND_SOC_DAIFMT_RIGHT_J:
> > -               lrck_period = params_physical_width(params) * slots;
> > +               lrck_period = slot_width * slots;
> >                 break;
> >
> >         case SND_SOC_DAIFMT_I2S:
> > -               lrck_period = params_physical_width(params);
> > +               lrck_period = slot_width;
> >                 break;
> >
> >         default: