linux-kernel - Re: [PATCH 4/7] ASoC: sun4i-i2s: Set sign extend sample

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Date:   Sat, 18 Apr 2020 23:30:16 +0200
From:   Clément Péron <peron.clem@...il.com>
To:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>, Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>
Cc:     Linux-ALSA <alsa-devel@...a-project.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Marcus Cooper <codekipper@...il.com>
Subject: Re: [PATCH 4/7] ASoC: sun4i-i2s: Set sign extend sample

Hi,

On Sat, 18 Apr 2020 at 16:39, Clément Péron <peron.clem@...il.com> wrote:
>
> From: Marcus Cooper <codekipper@...il.com>
>
> On the newer SoCs such as the H3 and A64 this is set by default
> to transfer a 0 after each sample in each slot. However the A10
> and A20 SoCs that this driver was developed on had a default
> setting where it padded the audio gain with zeros.
>
> This isn't a problem whilst we have only support for 16bit audio
> but with larger sample resolution rates in the pipeline then SEXT
> bits should be cleared so that they also pad at the LSB. Without
> this the audio gets distorted.
>
> Signed-off-by: Marcus Cooper <codekipper@...il.com>
> Signed-off-by: Clément Péron <peron.clem@...il.com>
> ---
>  sound/soc/sunxi/sun4i-i2s.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/sound/soc/sunxi/sun4i-i2s.c b/sound/soc/sunxi/sun4i-i2s.c
> index a23c9f2a3f8c..e5f00be8cdcf 100644
> --- a/sound/soc/sunxi/sun4i-i2s.c
> +++ b/sound/soc/sunxi/sun4i-i2s.c
> @@ -663,6 +663,12 @@ static int sun4i_i2s_set_soc_fmt(const struct sun4i_i2s *i2s,
>         }
>         regmap_update_bits(i2s->regmap, SUN4I_I2S_CTRL_REG,
>                            SUN4I_I2S_CTRL_MODE_MASK, val);
> +
> +       /* Set sign extension to pad out LSB with 0 */
> +       regmap_update_bits(i2s->regmap, SUN4I_I2S_FMT1_REG,
> +                          SUN4I_I2S_FMT1_REG_SEXT_MASK,
> +                          SUN4I_I2S_FMT1_REG_SEXT(0));

My apologies, I made a mistake during the rebase between old Marcus
Cooper patches and new one.
And sadly I lost the defines required here without noticing it.

Will send a v2.

Sorry for that,
Clement

> +
>         return 0;
>  }
>
> @@ -765,6 +771,11 @@ static int sun8i_i2s_set_soc_fmt(const struct sun4i_i2s *i2s,
>                            SUN8I_I2S_CTRL_BCLK_OUT | SUN8I_I2S_CTRL_LRCK_OUT,
>                            val);
>
> +       /* Set sign extension to pad out LSB with 0 */
> +       regmap_update_bits(i2s->regmap, SUN4I_I2S_FMT1_REG,
> +                          SUN8I_I2S_FMT1_REG_SEXT_MASK,
> +                          SUN8I_I2S_FMT1_REG_SEXT(0));
> +
>         return 0;
>  }
>
> @@ -867,6 +878,11 @@ static int sun50i_i2s_set_soc_fmt(const struct sun4i_i2s *i2s,
>                            SUN8I_I2S_CTRL_BCLK_OUT | SUN8I_I2S_CTRL_LRCK_OUT,
>                            val);
>
> +       /* Set sign extension to pad out LSB with 0 */
> +       regmap_update_bits(i2s->regmap, SUN4I_I2S_FMT1_REG,
> +                          SUN8I_I2S_FMT1_REG_SEXT_MASK,
> +                          SUN8I_I2S_FMT1_REG_SEXT(0));
> +
>         return 0;
>  }
>
> --
> 2.20.1
>