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

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Date:   Sun, 24 Oct 2021 23:12:39 +0300
From:   Vladimir Zapolskiy <vz@...ia.com>
To:     André Gustavo Nakagomi Lopez <andregnl@....br>,
        jic23@...nel.org, lars@...afoo.de
Cc:     linux-iio@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: adc: lpc18xx_adc: Reorder clk_get_rate function call

Hi André,

On 10/24/21 10:43 PM, André Gustavo Nakagomi Lopez wrote:
> clk_get_rate is not garanteed to work if called before clk_prepare_enable.

typo, s/garanteed/guaranteed/

> 
> Reorder clk_get_rate, so it's called after clk_prepare_enable and
> after devm_add_action_or_reset of lpc18xx_clk_disable.
> 
> Signed-off-by: André Gustavo Nakagomi Lopez <andregnl@....br>
> ---
>   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);
> 

Thank you for the change, per se this particular change is not needed on
LPC18xx/43xx platform, however I don't object to it.

Suggested-by: Jonathan Cameron <jic23@...nel.org>
Acked-by: Vladimir Zapolskiy <vz@...ia.com>

--
Best wishes,
Vladimir