Re: [PATCH 1/1] rtc: use devm_clk_get_enabled() in mv_rtc_probe()

[Alexandre Belloni <alexandre.belloni@bootlin.com>]

On 20/07/2023 22:08:14+0800, Yuanjun Gong wrote:
> in mv_rtc_probe(), the return value of function
> clk_prepare_enable() should be checked, since it may fail.
> using devm_clk_get_enabled() instead of devm_clk_get() and
> clk_prepare_enable() can avoid this problem.
> 
> Signed-off-by: Yuanjun Gong <ruc_gongyuanjun@163.com>
> ---
>  drivers/rtc/rtc-mv.c | 20 ++++++--------------
>  1 file changed, 6 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-mv.c b/drivers/rtc/rtc-mv.c
> index 6c526e2ec56d..8cd33721be03 100644
> --- a/drivers/rtc/rtc-mv.c
> +++ b/drivers/rtc/rtc-mv.c
> @@ -219,17 +219,16 @@ static int __init mv_rtc_probe(struct platform_device *pdev)
>  	if (IS_ERR(pdata->ioaddr))
>  		return PTR_ERR(pdata->ioaddr);
>  
> -	pdata->clk = devm_clk_get(&pdev->dev, NULL);
> +	pdata->clk = devm_clk_get_enabled(&pdev->dev, NULL);
>  	/* Not all SoCs require a clock.*/
> -	if (!IS_ERR(pdata->clk))
> -		clk_prepare_enable(pdata->clk);
> +	if (IS_ERR(pdata->clk))
> +		return PTR_ERR(pdata->clk);

Look at the comment, "Not all SoCs require a clock.", you are breaking
the driver for multiple platforms.

>  
>  	/* make sure the 24 hour mode is enabled */
>  	rtc_time = readl(pdata->ioaddr + RTC_TIME_REG_OFFS);
>  	if (rtc_time & RTC_HOURS_12H_MODE) {
>  		dev_err(&pdev->dev, "12 Hour mode is enabled but not supported.\n");
> -		ret = -EINVAL;
> -		goto out;
> +		return -EINVAL;
>  	}
>  
>  	/* make sure it is actually functional */
> @@ -238,8 +237,7 @@ static int __init mv_rtc_probe(struct platform_device *pdev)
>  		rtc_time = readl(pdata->ioaddr + RTC_TIME_REG_OFFS);
>  		if (rtc_time == 0x01000000) {
>  			dev_err(&pdev->dev, "internal RTC not ticking\n");
> -			ret = -ENODEV;
> -			goto out;
> +			return -ENODEV;
>  		}
>  	}
>  
> @@ -249,8 +247,7 @@ static int __init mv_rtc_probe(struct platform_device *pdev)
>  
>  	pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
>  	if (IS_ERR(pdata->rtc)) {
> -		ret = PTR_ERR(pdata->rtc);
> -		goto out;
> +		return PTR_ERR(pdata->rtc);
>  	}
>  
>  	if (pdata->irq >= 0) {
> @@ -275,11 +272,6 @@ static int __init mv_rtc_probe(struct platform_device *pdev)
>  	ret = devm_rtc_register_device(pdata->rtc);
>  	if (!ret)
>  		return 0;
> -out:
> -	if (!IS_ERR(pdata->clk))
> -		clk_disable_unprepare(pdata->clk);
> -
> -	return ret;
>  }
>  
>  static int __exit mv_rtc_remove(struct platform_device *pdev)
> -- 
> 2.17.1
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com