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Date:   Mon, 19 Oct 2020 12:24:43 +0200
From:   Maxime Ripard <maxime@cerno.tech>
To:     Samuel Holland <samuel@sholland.org>
Cc:     =?utf-8?B?Q2zDqW1lbnQgUMOpcm9u?= <peron.clem@gmail.com>,
        Chen-Yu Tsai <wens@csie.org>, Rob Herring <robh+dt@kernel.org>,
        Mark Brown <broonie@kernel.org>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Jaroslav Kysela <perex@perex.cz>,
        Takashi Iwai <tiwai@suse.com>,
        Marcus Cooper <codekipper@gmail.com>,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Linux-ALSA <alsa-devel@alsa-project.org>,
        devicetree <devicetree@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        linux-sunxi <linux-sunxi@googlegroups.com>
Subject: Re: [PATCH v6 02/14] ASoC: sun4i-i2s: Change set_chan_cfg() params
Message-ID: <20201019102443.uk3t2jcqc7x7rxdi@gilmour.lan>
References: <20201003141950.455829-1-peron.clem@gmail.com>
 <20201003141950.455829-3-peron.clem@gmail.com>
 <20201005121307.v6jpyeyfi4kxc2cl@gilmour.lan>
 <CAJiuCcdd6_kzsxEERZbj2Budjmuyv6gV_sPG8LjLY=fk+MO8zQ@mail.gmail.com>
 <20201012121536.z5d7kecdxaabw35n@gilmour.lan>
 <0d6f0693-5ca9-9b48-4d33-a969bd5b1b1b@sholland.org>
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Hi Samuel,

On Mon, Oct 12, 2020 at 08:15:30PM -0500, Samuel Holland wrote:
> On 10/12/20 7:15 AM, Maxime Ripard wrote:
> > Hi,
> >=20
> > On Mon, Oct 05, 2020 at 03:23:12PM +0200, Cl=E9ment P=E9ron wrote:
> >> On Mon, 5 Oct 2020 at 14:13, Maxime Ripard <maxime@cerno.tech> wrote:
> >>>
> >>> On Sat, Oct 03, 2020 at 04:19:38PM +0200, Cl=E9ment P=E9ron wrote:
> >>>> As slots and slot_width can be set manually using set_tdm().
> >>>> These values are then kept in sun4i_i2s struct.
> >>>> So we need to check if these values are setted or not
> >>>> in the struct.
> >>>>
> >>>> Avoid to check for this logic in set_chan_cfg(). This will
> >>>> duplicate the same check 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@sholland.org>
> >>>> Signed-off-by: Cl=E9ment P=E9ron <peron.clem@gmail.com>
> >>>> ---
> >>>>  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=
=2Ec
> >>>> index c5ccd423e6d3..1f577dbc20a6 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 s=
lots,
> >>>> +                             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 sun=
4i_i2s *i2s, int width)
> >>>>  }
> >>>>
> >>>>  static int sun4i_i2s_set_chan_cfg(const struct sun4i_i2s *i2s,
> >>>> -                               const struct snd_pcm_hw_params *para=
ms)
> >>>> +                               unsigned int channels, unsigned int =
slots,
> >>>> +                               unsigned int slot_width)
> >>>>  {
> >>>> -     unsigned int channels =3D params_channels(params);
> >>>> -
> >>>>       /* Map the channels for playback and capture */
> >>>>       regmap_write(i2s->regmap, SUN4I_I2S_TX_CHAN_MAP_REG, 0x7654321=
0);
> >>>>       regmap_write(i2s->regmap, SUN4I_I2S_RX_CHAN_MAP_REG, 0x0000321=
0);
> >>>> @@ -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 *para=
ms)
> >>>> +                               unsigned int channels, unsigned int =
slots,
> >>>> +                               unsigned int slot_width)
> >>>>  {
> >>>> -     unsigned int channels =3D params_channels(params);
> >>>> -     unsigned int slots =3D channels;
> >>>>       unsigned int lrck_period;
> >>>>
> >>>> -     if (i2s->slots)
> >>>> -             slots =3D i2s->slots;
> >>>> -
> >>>>       /* Map the channels for playback and capture */
> >>>>       regmap_write(i2s->regmap, SUN8I_I2S_TX_CHAN_MAP_REG, 0x7654321=
0);
> >>>>       regmap_write(i2s->regmap, SUN8I_I2S_RX_CHAN_MAP_REG, 0x7654321=
0);
> >>>> @@ -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 =3D params_physical_width(params) * slots;
> >>>> +             lrck_period =3D slot_width * slots;
> >>>>               break;
> >>>>
> >>>>       case SND_SOC_DAIFMT_I2S:
> >>>> -             lrck_period =3D params_physical_width(params);
> >>>> +             lrck_period =3D slot_width;
> >>>>               break;
> >>>>
> >>>>       default:
> >>>> @@ -490,15 +486,11 @@ static int sun8i_i2s_set_chan_cfg(const struct=
 sun4i_i2s *i2s,
> >>>>  }
> >>>>
> >>>>  static int sun50i_h6_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 =3D params_channels(params);
> >>>> -     unsigned int slots =3D channels;
> >>>>       unsigned int lrck_period;
> >>>>
> >>>> -     if (i2s->slots)
> >>>> -             slots =3D i2s->slots;
> >>>> -
> >>>>       /* Map the channels for playback and capture */
> >>>>       regmap_write(i2s->regmap, SUN50I_H6_I2S_TX_CHAN_MAP0_REG, 0xFE=
DCBA98);
> >>>>       regmap_write(i2s->regmap, SUN50I_H6_I2S_TX_CHAN_MAP1_REG, 0x76=
543210);
> >>>> @@ -525,11 +517,11 @@ static int sun50i_h6_i2s_set_chan_cfg(const st=
ruct sun4i_i2s *i2s,
> >>>>       case SND_SOC_DAIFMT_DSP_B:
> >>>>       case SND_SOC_DAIFMT_LEFT_J:
> >>>>       case SND_SOC_DAIFMT_RIGHT_J:
> >>>> -             lrck_period =3D params_physical_width(params) * slots;
> >>>> +             lrck_period =3D slot_width * slots;
> >>>>               break;
> >>>>
> >>>>       case SND_SOC_DAIFMT_I2S:
> >>>> -             lrck_period =3D params_physical_width(params);
> >>>> +             lrck_period =3D slot_width;
> >>>>               break;
> >>>>
> >>>>       default:
> >>>> @@ -565,7 +557,7 @@ static int sun4i_i2s_hw_params(struct snd_pcm_su=
bstream *substream,
> >>>>       if (i2s->slot_width)
> >>>>               slot_width =3D i2s->slot_width;
> >>>>
> >>>> -     ret =3D i2s->variant->set_chan_cfg(i2s, params);
> >>>> +     ret =3D i2s->variant->set_chan_cfg(i2s, channels, slots, slot_=
width);
> >>>
> >>> Isn't slots and slot_width set to 0 here ?
> >>
> >> No, there is still a check before calling the set_cfg function.
> >>
> >>   unsigned int slot_width =3D params_physical_width(params);
> >>   unsigned int channels =3D params_channels(params);
> >>   unsigned int slots =3D channels;
> >>
> >>   if (i2s->slots)
> >>   slots =3D i2s->slots;
> >>
> >>   if (i2s->slot_width)
> >>   slot_width =3D i2s->slot_width;
> >>
> >> ret =3D i2s->variant->set_chan_cfg(i2s, channels, slots, slot_width);
> >>
> >> So slot_width will be equal to params_physical_width(params);
> >> like before
> >=20
> > Still, it's not obvious what slots and slot_width are going to be set to
> > in a non-TDM setup where that doesn't really make much sense.
>=20
> My understanding is:
>=20
> "slots" is channels per frame + padding slots, regardless of format.
> "slot_width" is bits per sample + padding bits, regardless of format.
>=20
> Some formats may require or prohibit certain padding, but that has no
> effect on the definitions.
>=20
> That seems clear to me? At least that's what I implemented (and you
> acked) in sun8i-codec.

Yeah I guess you're right. I'd still like at least a comment on top of
the function making that clear so that no-one's confused

Maxime

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