linux-kernel - Re: [PATCH 2/4] ASoC: codecs: lpass-rx-macro: Keep static regmap

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Date: Fri, 28 Jun 2024 11:34:49 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>, 
	Banajit Goswami <bgoswami@...cinc.com>, Liam Girdwood <lgirdwood@...il.com>, 
	Mark Brown <broonie@...nel.org>, Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>, 
	alsa-devel@...a-project.org, linux-arm-msm@...r.kernel.org, linux-sound@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] ASoC: codecs: lpass-rx-macro: Keep static
 regmap_config as const

On Thu, Jun 27, 2024 at 05:23:44PM GMT, Krzysztof Kozlowski wrote:
> The driver has static 'struct regmap_config', which is then customized
> depending on device version.  This works fine, because there should not
> be two devices in a system simultaneously and even less likely that such
> two devices would have different versions, thus different regmap config.
> However code is cleaner and more obvious when static data in the driver
> is also const - it serves as a template.
> 
> Mark the 'struct regmap_config' as const and duplicate it in the probe()
> with devm_kmemdup to allow customizing per detected device variant.
> 
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> ---
>  sound/soc/codecs/lpass-rx-macro.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

> 
> diff --git a/sound/soc/codecs/lpass-rx-macro.c b/sound/soc/codecs/lpass-rx-macro.c
> index 59fe76b13cdb..3d8149665439 100644
> --- a/sound/soc/codecs/lpass-rx-macro.c
> +++ b/sound/soc/codecs/lpass-rx-macro.c
> @@ -1662,7 +1662,7 @@ static bool rx_is_readable_register(struct device *dev, unsigned int reg)
>  	return rx_is_rw_register(dev, reg);
>  }
>  
> -static struct regmap_config rx_regmap_config = {
> +static const struct regmap_config rx_regmap_config = {
>  	.name = "rx_macro",
>  	.reg_bits = 16,
>  	.val_bits = 32, /* 8 but with 32 bit read/write */
> @@ -3765,6 +3765,7 @@ static const struct snd_soc_component_driver rx_macro_component_drv = {
>  static int rx_macro_probe(struct platform_device *pdev)
>  {
>  	struct reg_default *reg_defaults;
> +	struct regmap_config *reg_config;
>  	struct device *dev = &pdev->dev;
>  	kernel_ulong_t flags;
>  	struct rx_macro *rx;
> @@ -3851,14 +3852,22 @@ static int rx_macro_probe(struct platform_device *pdev)
>  		goto err;
>  	}
>  
> -	rx_regmap_config.reg_defaults = reg_defaults;
> -	rx_regmap_config.num_reg_defaults = def_count;
> +	reg_config = devm_kmemdup(dev, &rx_regmap_config, sizeof(*reg_config),
> +				  GFP_KERNEL);
> +	if (!reg_config) {
> +		ret = -ENOMEM;
> +		goto err;
> +	}
>  
> -	rx->regmap = devm_regmap_init_mmio(dev, base, &rx_regmap_config);
> +	reg_config->reg_defaults = reg_defaults;
> +	reg_config->num_reg_defaults = def_count;
> +
> +	rx->regmap = devm_regmap_init_mmio(dev, base, reg_config);
>  	if (IS_ERR(rx->regmap)) {
>  		ret = PTR_ERR(rx->regmap);
>  		goto err;
>  	}
> +	devm_kfree(dev, reg_config);
>  	devm_kfree(dev, reg_defaults);

Seeing devm_kfree in the non-error path makes me feel strange. Maybe
it's one of the rare occasions when I can say that __free is suitable
here.

>  
>  	dev_set_drvdata(dev, rx);
> 
> -- 
> 2.43.0
> 

-- 
With best wishes
Dmitry