linux-kernel - Re: [linux-sunxi] [PATCH v5 15/15] ASoC: sun4i-i2s: Adjust regmap settings

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Date:   Wed, 14 Aug 2019 10:37:52 +0200
From:   Jernej Škrabec <jernej.skrabec@...il.com>
To:     linux-sunxi@...glegroups.com, codekipper@...il.com
Cc:     maxime.ripard@...e-electrons.com, wens@...e.org,
        linux-arm-kernel@...ts.infradead.org, lgirdwood@...il.com,
        broonie@...nel.org, linux-kernel@...r.kernel.org,
        alsa-devel@...a-project.org, be17068@...rbole.bo.it
Subject: Re: [linux-sunxi] [PATCH v5 15/15] ASoC: sun4i-i2s: Adjust regmap settings

Hi!

Dne sreda, 14. avgust 2019 ob 08:08:54 CEST je codekipper@...il.com 
napisal(a):
> From: Marcus Cooper <codekipper@...il.com>
> 
> Bypass the regmap cache when flushing the i2s FIFOs and modify the tables
> to reflect this.
> 
> Signed-off-by: Marcus Cooper <codekipper@...il.com>
> ---
>  sound/soc/sunxi/sun4i-i2s.c | 31 ++++++++++---------------------
>  1 file changed, 10 insertions(+), 21 deletions(-)
> 
> diff --git a/sound/soc/sunxi/sun4i-i2s.c b/sound/soc/sunxi/sun4i-i2s.c
> index d3c8789f70bb..ecfc1ed79379 100644
> --- a/sound/soc/sunxi/sun4i-i2s.c
> +++ b/sound/soc/sunxi/sun4i-i2s.c
> @@ -876,9 +876,11 @@ static int sun4i_i2s_set_fmt(struct snd_soc_dai *dai,
> unsigned int fmt) static void sun4i_i2s_start_capture(struct sun4i_i2s
> *i2s)
>  {
>  	/* Flush RX FIFO */
> +	regcache_cache_bypass(i2s->regmap, true);
>  	regmap_update_bits(i2s->regmap, SUN4I_I2S_FIFO_CTRL_REG,
>  			   SUN4I_I2S_FIFO_CTRL_FLUSH_RX,
>  			   SUN4I_I2S_FIFO_CTRL_FLUSH_RX);
> +	regcache_cache_bypass(i2s->regmap, false);

Did you try with regmap_write_bits() instead? This function will 
unconditionally write bits so it's nicer solution, because you don't have to 
use regcache_cache_bypass().

> 
>  	/* Clear RX counter */
>  	regmap_write(i2s->regmap, SUN4I_I2S_RX_CNT_REG, 0);
> @@ -897,9 +899,11 @@ static void sun4i_i2s_start_capture(struct sun4i_i2s
> *i2s) static void sun4i_i2s_start_playback(struct sun4i_i2s *i2s)
>  {
>  	/* Flush TX FIFO */
> +	regcache_cache_bypass(i2s->regmap, true);
>  	regmap_update_bits(i2s->regmap, SUN4I_I2S_FIFO_CTRL_REG,
>  			   SUN4I_I2S_FIFO_CTRL_FLUSH_TX,
>  			   SUN4I_I2S_FIFO_CTRL_FLUSH_TX);
> +	regcache_cache_bypass(i2s->regmap, false);

Ditto.

> 
>  	/* Clear TX counter */
>  	regmap_write(i2s->regmap, SUN4I_I2S_TX_CNT_REG, 0);
> @@ -1053,13 +1057,7 @@ static const struct snd_soc_component_driver
> sun4i_i2s_component = {
> 
>  static bool sun4i_i2s_rd_reg(struct device *dev, unsigned int reg)
>  {
> -	switch (reg) {
> -	case SUN4I_I2S_FIFO_TX_REG:
> -		return false;
> -
> -	default:
> -		return true;
> -	}
> +	return true;

Why did you change this? Manual mentions that SUN4I_I2S_FIFO_TX_REG is write-
only register. Even if it can be read, then it's better to remove whole 
function, which will automatically mean that all registers can be read.


>  }
> 
>  static bool sun4i_i2s_wr_reg(struct device *dev, unsigned int reg)
> @@ -1078,6 +1076,8 @@ static bool sun4i_i2s_volatile_reg(struct device *dev,
> unsigned int reg) {
>  	switch (reg) {
>  	case SUN4I_I2S_FIFO_RX_REG:
> +	case SUN4I_I2S_FIFO_TX_REG:
> +	case SUN4I_I2S_FIFO_STA_REG:
>  	case SUN4I_I2S_INT_STA_REG:
>  	case SUN4I_I2S_RX_CNT_REG:
>  	case SUN4I_I2S_TX_CNT_REG:

SUN4I_I2S_FIFO_CTRL_REG should be put here, because it has two bits which 
returns to 0 immediately after they are set to 1.

Best regards,
Jernej

> @@ -1088,23 +1088,12 @@ static bool sun4i_i2s_volatile_reg(struct device
> *dev, unsigned int reg) }
>  }
> 
> -static bool sun8i_i2s_rd_reg(struct device *dev, unsigned int reg)
> -{
> -	switch (reg) {
> -	case SUN8I_I2S_FIFO_TX_REG:
> -		return false;
> -
> -	default:
> -		return true;
> -	}
> -}
> -
>  static bool sun8i_i2s_volatile_reg(struct device *dev, unsigned int reg)
>  {
>  	if (reg == SUN8I_I2S_INT_STA_REG)
>  		return true;
>  	if (reg == SUN8I_I2S_FIFO_TX_REG)
> -		return false;
> +		return true;
> 
>  	return sun4i_i2s_volatile_reg(dev, reg);
>  }
> @@ -1175,7 +1164,7 @@ static const struct regmap_config
> sun8i_i2s_regmap_config = { .reg_defaults	= sun8i_i2s_reg_defaults,
>  	.num_reg_defaults	= ARRAY_SIZE(sun8i_i2s_reg_defaults),
>  	.writeable_reg	= sun4i_i2s_wr_reg,
> -	.readable_reg	= sun8i_i2s_rd_reg,
> +	.readable_reg	= sun4i_i2s_rd_reg,
>  	.volatile_reg	= sun8i_i2s_volatile_reg,
>  };
> 
> @@ -1188,7 +1177,7 @@ static const struct regmap_config
> sun50i_i2s_regmap_config = { .reg_defaults	= sun50i_i2s_reg_defaults,
>  	.num_reg_defaults	= ARRAY_SIZE(sun50i_i2s_reg_defaults),
>  	.writeable_reg	= sun4i_i2s_wr_reg,
> -	.readable_reg	= sun8i_i2s_rd_reg,
> +	.readable_reg	= sun4i_i2s_rd_reg,
>  	.volatile_reg	= sun8i_i2s_volatile_reg,
>  };