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Subject: Re: [PATCH 1/5] i2c: i2c-stm32f7: disable/restore Fast Mode Plus bits
 in low power modes
To:     Alain Volmat <alain.volmat@st.com>, <wsa@the-dreams.de>,
        <robh+dt@kernel.org>
CC:     <mark.rutland@arm.com>, <mcoquelin.stm32@gmail.com>,
        <alexandre.torgue@st.com>, <linux-i2c@vger.kernel.org>,
        <devicetree@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <fabrice.gasnier@st.com>
References: <1579795970-22319-1-git-send-email-alain.volmat@st.com>
 <1579795970-22319-2-git-send-email-alain.volmat@st.com>
From:   Pierre Yves MORDRET <pierre-yves.mordret@st.com>
Message-ID: <4e92ad2d-d373-f009-7c79-63d7caafac45@st.com>
Date:   Mon, 27 Jan 2020 10:18:57 +0100
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Hello

Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>

Thanks

On 1/23/20 5:12 PM, Alain Volmat wrote:
> Defer the initial enabling of the Fast Mode Plus bits after the
> stm32f7_i2c_setup_timing call in probe function in order to avoid
> enabling them if speed is downgraded.
> Clear & restore the Fast Mode Plus bits in the suspend/resume
> handlers of the driver.
> 
> Signed-off-by: Alain Volmat <alain.volmat@st.com>
> ---
>  drivers/i2c/busses/i2c-stm32f7.c | 48 +++++++++++++++++++++++++++++++++-------
>  1 file changed, 40 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
> index 844a22d64aa8..1a3b3fa582ff 100644
> --- a/drivers/i2c/busses/i2c-stm32f7.c
> +++ b/drivers/i2c/busses/i2c-stm32f7.c
> @@ -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;
>  	bool wakeup_src;
>  };
>  
> @@ -1815,12 +1819,25 @@ static int stm32f7_i2c_unreg_slave(struct i2c_client *slave)
>  	return 0;
>  }
>  
> +static int stm32f7_i2c_write_fm_plus_bits(struct stm32f7_i2c_dev *i2c_dev,
> +					  bool enable)
> +{
> +	if (i2c_dev->speed != STM32_I2C_SPEED_FAST_PLUS ||
> +	    IS_ERR_OR_NULL(i2c_dev->regmap)) {
> +		/* Optional */
> +		return 0;
> +	}
> +
> +	return regmap_update_bits(i2c_dev->regmap, i2c_dev->regmap_reg,
> +				  i2c_dev->regmap_mask,
> +				  enable ? i2c_dev->regmap_mask : 0);
> +}
> +
>  static int stm32f7_i2c_setup_fm_plus_bits(struct platform_device *pdev,
>  					  struct stm32f7_i2c_dev *i2c_dev)
>  {
>  	struct device_node *np = pdev->dev.of_node;
>  	int ret;
> -	u32 reg, mask;
>  
>  	i2c_dev->regmap = syscon_regmap_lookup_by_phandle(np, "st,syscfg-fmp");
>  	if (IS_ERR(i2c_dev->regmap)) {
> @@ -1828,15 +1845,17 @@ static int stm32f7_i2c_setup_fm_plus_bits(struct platform_device *pdev,
>  		return 0;
>  	}
>  
> -	ret = of_property_read_u32_index(np, "st,syscfg-fmp", 1, &reg);
> +	ret = of_property_read_u32_index(np, "st,syscfg-fmp", 1,
> +					 &i2c_dev->regmap_reg);
>  	if (ret)
>  		return ret;
>  
> -	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;
>  }
>  
>  static u32 stm32f7_i2c_func(struct i2c_adapter *adap)
> @@ -1914,9 +1933,6 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
>  				       &clk_rate);
>  	if (!ret && clk_rate >= 1000000) {
>  		i2c_dev->speed = STM32_I2C_SPEED_FAST_PLUS;
> -		ret = stm32f7_i2c_setup_fm_plus_bits(pdev, i2c_dev);
> -		if (ret)
> -			goto clk_free;
>  	} else if (!ret && clk_rate >= 400000) {
>  		i2c_dev->speed = STM32_I2C_SPEED_FAST;
>  	} else if (!ret && clk_rate >= 100000) {
> @@ -1976,6 +1992,15 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto clk_free;
>  
> +	if (i2c_dev->speed == STM32_I2C_SPEED_FAST_PLUS) {
> +		ret = stm32f7_i2c_setup_fm_plus_bits(pdev, i2c_dev);
> +		if (ret)
> +			goto clk_free;
> +		ret = stm32f7_i2c_write_fm_plus_bits(i2c_dev, 1);
> +		if (ret)
> +			goto clk_free;
> +	}
> +
>  	adap = &i2c_dev->adap;
>  	i2c_set_adapdata(adap, i2c_dev);
>  	snprintf(adap->name, sizeof(adap->name), "STM32F7 I2C(%pa)",
> @@ -2000,7 +2025,7 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
>  		if (ret != -EPROBE_DEFER)
>  			dev_err(&pdev->dev,
>  				"Failed to request dma error %i\n", ret);
> -		goto clk_free;
> +		goto fmp_clear;
>  	}
>  
>  	if (i2c_dev->wakeup_src) {
> @@ -2054,6 +2079,9 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
>  		i2c_dev->dma = NULL;
>  	}
>  
> +fmp_clear:
> +	stm32f7_i2c_write_fm_plus_bits(i2c_dev, 0);
> +
>  clk_free:
>  	clk_disable_unprepare(i2c_dev->clk);
>  
> @@ -2086,6 +2114,8 @@ static int stm32f7_i2c_remove(struct platform_device *pdev)
>  		i2c_dev->dma = NULL;
>  	}
>  
> +	stm32f7_i2c_write_fm_plus_bits(i2c_dev, 0);
> +
>  	clk_disable_unprepare(i2c_dev->clk);
>  
>  	return 0;
> @@ -2133,6 +2163,7 @@ stm32f7_i2c_regs_backup(struct stm32f7_i2c_dev *i2c_dev)
>  	backup_regs->oar2 = readl_relaxed(i2c_dev->base + STM32F7_I2C_OAR2);
>  	backup_regs->pecr = readl_relaxed(i2c_dev->base + STM32F7_I2C_PECR);
>  	backup_regs->tmgr = readl_relaxed(i2c_dev->base + STM32F7_I2C_TIMINGR);
> +	stm32f7_i2c_write_fm_plus_bits(i2c_dev, 0);
>  
>  	pm_runtime_put_sync(i2c_dev->dev);
>  
> @@ -2165,6 +2196,7 @@ stm32f7_i2c_regs_restore(struct stm32f7_i2c_dev *i2c_dev)
>  	writel_relaxed(backup_regs->oar1, i2c_dev->base + STM32F7_I2C_OAR1);
>  	writel_relaxed(backup_regs->oar2, i2c_dev->base + STM32F7_I2C_OAR2);
>  	writel_relaxed(backup_regs->pecr, i2c_dev->base + STM32F7_I2C_PECR);
> +	stm32f7_i2c_write_fm_plus_bits(i2c_dev, 1);
>  
>  	pm_runtime_put_sync(i2c_dev->dev);
>  
>