linux-kernel - Re: [PATCH 1/5] i2c: i2c-stm32f7: disable/restore Fast Mode Plus bits in low power modes

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Date:   Sat, 22 Feb 2020 13:34:57 +0100
From:   Wolfram Sang <wsa@...-dreams.de>
To:     Alain Volmat <alain.volmat@...com>
Cc:     robh+dt@...nel.org, mark.rutland@....com,
        pierre-yves.mordret@...com, mcoquelin.stm32@...il.com,
        alexandre.torgue@...com, linux-i2c@...r.kernel.org,
        devicetree@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        fabrice.gasnier@...com
Subject: Re: [PATCH 1/5] i2c: i2c-stm32f7: disable/restore Fast Mode Plus
 bits in low power modes

Hi Alain,

thanks for the patch. A few comments:

> @@ -303,6 +303,8 @@ struct stm32f7_i2c_msg {
>   * @dma: dma data
>   * @use_dma: boolean to know if dma is used in the current transfer
>   * @regmap: holds SYSCFG phandle for Fast Mode Plus bits
> + * @regmap_reg: register address for setting Fast Mode Plus bits
> + * @regmap_mask: mask for Fast Mode Plus bits in set register
>   * @wakeup_src: boolean to know if the device is a wakeup source
>   */
>  struct stm32f7_i2c_dev {
> @@ -326,6 +328,8 @@ struct stm32f7_i2c_dev {
>  	struct stm32_i2c_dma *dma;
>  	bool use_dma;
>  	struct regmap *regmap;
> +	u32 regmap_reg;
> +	u32 regmap_mask;

Is this really a descriptive naming? From looking at the code,
'syscfg_reg' or 'fmp_reg' sound more suitable to me?

> +{
> +	if (i2c_dev->speed != STM32_I2C_SPEED_FAST_PLUS ||
> +	    IS_ERR_OR_NULL(i2c_dev->regmap)) {
> +		/* Optional */
> +		return 0;
> +	}

No brackets needed here.


> -	ret = of_property_read_u32_index(np, "st,syscfg-fmp", 2, &mask);
> +	ret = of_property_read_u32_index(np, "st,syscfg-fmp", 2,
> +					 &i2c_dev->regmap_mask);
>  	if (ret)
>  		return ret;
>  
> -	return regmap_update_bits(i2c_dev->regmap, reg, mask, mask);
> +	return 0;

Can be shortened now to
	return of_property_read_u32_index(...);

> +		ret = stm32f7_i2c_write_fm_plus_bits(i2c_dev, 1);

The type of the last parameter is bool, so using 'true/false' instead of
'1/0' is a tad more readable, I think.

Regards,

   Wolfram


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