linux-kernel - Re: [PATCH v2] iio: adc: lpc18xx_adc: Reorder clk_get

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Message-ID: <20211028144041.20407149@jic23-huawei>
Date:   Thu, 28 Oct 2021 14:40:41 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     André Gustavo Nakagomi Lopez <andregnl@....br>
Cc:     lars@...afoo.de, vz@...ia.com, linux-iio@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] iio: adc: lpc18xx_adc: Reorder clk_get_rate function
 call

On Mon, 25 Oct 2021 09:19:50 -0300
André Gustavo Nakagomi Lopez <andregnl@....br> wrote:

> clk_get_rate is not guaranteed to work if called before clk_prepare_enable.
> 
> Reorder clk_get_rate, so it's called after clk_prepare_enable and
> after devm_add_action_or_reset of lpc18xx_clk_disable.
> 
> Suggested-by: Jonathan Cameron <jic23@...nel.org>
> Acked-by: Vladimir Zapolskiy <vz@...ia.com>
> Signed-off-by: André Gustavo Nakagomi Lopez <andregnl@....br>

Thanks. I tweaked the message a little and added a note that this was not
a fix for this particular platform.  Good to avoid chance of cut and paste
into another driver!

Jonathan

> ---
> Change log V1 -> V2:
> 		  -Fixed typo
> 		  -Added appropriate Suggested-by and Acked-by tags
>  drivers/iio/adc/lpc18xx_adc.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/adc/lpc18xx_adc.c b/drivers/iio/adc/lpc18xx_adc.c
> index ceefa4d793cf..ae9c9384f23e 100644
> --- a/drivers/iio/adc/lpc18xx_adc.c
> +++ b/drivers/iio/adc/lpc18xx_adc.c
> @@ -157,9 +157,6 @@ static int lpc18xx_adc_probe(struct platform_device *pdev)
>  		return dev_err_probe(&pdev->dev, PTR_ERR(adc->clk),
>  				     "error getting clock\n");
>  
> -	rate = clk_get_rate(adc->clk);
> -	clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET);
> -
>  	adc->vref = devm_regulator_get(&pdev->dev, "vref");
>  	if (IS_ERR(adc->vref))
>  		return dev_err_probe(&pdev->dev, PTR_ERR(adc->vref),
> @@ -192,6 +189,9 @@ static int lpc18xx_adc_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> +	rate = clk_get_rate(adc->clk);
> +	clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET);
> +
>  	adc->cr_reg = (clkdiv << LPC18XX_ADC_CR_CLKDIV_SHIFT) |
>  			LPC18XX_ADC_CR_PDN;
>  	writel(adc->cr_reg, adc->base + LPC18XX_ADC_CR);