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From:   Chen-Yu Tsai <wens@csie.org>
Date:   Mon, 28 Sep 2020 13:00:45 +0800
Message-ID: <CAGb2v669XXerfrgK9WzAoMHwArn765yS9Db4_xwwQSXpnm2zqQ@mail.gmail.com>
Subject: Re: [linux-sunxi] [PATCH v5 02/20] ASoC: sun4i-i2s: Change
 set_chan_cfg() params
To:     =?UTF-8?B?Q2zDqW1lbnQgUMOpcm9u?= <peron.clem@gmail.com>
Cc:     Maxime Ripard <mripard@kernel.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>,
        Samuel Holland <samuel@sholland.org>
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On Mon, Sep 28, 2020 at 3:29 AM Clément Péron <peron.clem@gmail.com> 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.

> 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: Clément Péron <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.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.

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.


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: