linux-kernel - Re: [PATCH] watchdog: imgpdc: Use devm_clk_get

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Date:   Sat, 31 Dec 2022 15:09:40 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-watchdog@...r.kernel.org
Subject: Re: [PATCH] watchdog: imgpdc: Use devm_clk_get_enabled() helper

On Sat, Dec 31, 2022 at 11:53:34AM +0100, Christophe JAILLET wrote:
> The devm_clk_get_enabled() helper:
>    - calls devm_clk_get()
>    - calls clk_prepare_enable() and registers what is needed in order to
>      call clk_disable_unprepare() when needed, as a managed resource.
> 
> This simplifies the code and avoids the need of a dedicated function used
> with devm_add_action_or_reset().
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
> Note that the order of operations is slightly modified by this patch. The
> "sys" clk is now prepare_enable()'ed before clk_get("wdt").
> ---
>  drivers/watchdog/imgpdc_wdt.c | 31 +++----------------------------
>  1 file changed, 3 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/watchdog/imgpdc_wdt.c b/drivers/watchdog/imgpdc_wdt.c
> index b57ff3787052..a55f801895d4 100644
> --- a/drivers/watchdog/imgpdc_wdt.c
> +++ b/drivers/watchdog/imgpdc_wdt.c
> @@ -175,16 +175,11 @@ static const struct watchdog_ops pdc_wdt_ops = {
>  	.restart        = pdc_wdt_restart,
>  };
>  
> -static void pdc_clk_disable_unprepare(void *data)
> -{
> -	clk_disable_unprepare(data);
> -}
> -
>  static int pdc_wdt_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
>  	u64 div;
> -	int ret, val;
> +	int val;
>  	unsigned long clk_rate;
>  	struct pdc_wdt_dev *pdc_wdt;
>  
> @@ -196,38 +191,18 @@ static int pdc_wdt_probe(struct platform_device *pdev)
>  	if (IS_ERR(pdc_wdt->base))
>  		return PTR_ERR(pdc_wdt->base);
>  
> -	pdc_wdt->sys_clk = devm_clk_get(dev, "sys");
> +	pdc_wdt->sys_clk = devm_clk_get_enabled(dev, "sys");
>  	if (IS_ERR(pdc_wdt->sys_clk)) {
>  		dev_err(dev, "failed to get the sys clock\n");
>  		return PTR_ERR(pdc_wdt->sys_clk);
>  	}
>  
> -	pdc_wdt->wdt_clk = devm_clk_get(dev, "wdt");
> +	pdc_wdt->wdt_clk = devm_clk_get_enabled(dev, "wdt");
>  	if (IS_ERR(pdc_wdt->wdt_clk)) {
>  		dev_err(dev, "failed to get the wdt clock\n");
>  		return PTR_ERR(pdc_wdt->wdt_clk);
>  	}
>  
> -	ret = clk_prepare_enable(pdc_wdt->sys_clk);
> -	if (ret) {
> -		dev_err(dev, "could not prepare or enable sys clock\n");
> -		return ret;
> -	}
> -	ret = devm_add_action_or_reset(dev, pdc_clk_disable_unprepare,
> -				       pdc_wdt->sys_clk);
> -	if (ret)
> -		return ret;
> -
> -	ret = clk_prepare_enable(pdc_wdt->wdt_clk);
> -	if (ret) {
> -		dev_err(dev, "could not prepare or enable wdt clock\n");
> -		return ret;
> -	}
> -	ret = devm_add_action_or_reset(dev, pdc_clk_disable_unprepare,
> -				       pdc_wdt->wdt_clk);
> -	if (ret)
> -		return ret;
> -
>  	/* We use the clock rate to calculate the max timeout */
>  	clk_rate = clk_get_rate(pdc_wdt->wdt_clk);
>  	if (clk_rate == 0) {
> -- 
> 2.34.1
>