linux-kernel - Re: [PATCH] watchdog: lpc18xx: Use devm_clk_get

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Message-ID: <20230103211325.GA212337@roeck-us.net>
Date:   Tue, 3 Jan 2023 13:13:25 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Vladimir Zapolskiy <vz@...ia.com>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-watchdog@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] watchdog: lpc18xx: Use devm_clk_get_enabled() helper

On Sat, Dec 31, 2022 at 01:26:09PM +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
> "reg" clk is now prepare_enable()'ed before clk_get("wdtclk").
> ---
>  drivers/watchdog/lpc18xx_wdt.c | 30 ++----------------------------
>  1 file changed, 2 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/watchdog/lpc18xx_wdt.c b/drivers/watchdog/lpc18xx_wdt.c
> index 60b6d74f267d..1b9b5f21a0df 100644
> --- a/drivers/watchdog/lpc18xx_wdt.c
> +++ b/drivers/watchdog/lpc18xx_wdt.c
> @@ -197,16 +197,10 @@ static const struct watchdog_ops lpc18xx_wdt_ops = {
>  	.restart        = lpc18xx_wdt_restart,
>  };
>  
> -static void lpc18xx_clk_disable_unprepare(void *data)
> -{
> -	clk_disable_unprepare(data);
> -}
> -
>  static int lpc18xx_wdt_probe(struct platform_device *pdev)
>  {
>  	struct lpc18xx_wdt_dev *lpc18xx_wdt;
>  	struct device *dev = &pdev->dev;
> -	int ret;
>  
>  	lpc18xx_wdt = devm_kzalloc(dev, sizeof(*lpc18xx_wdt), GFP_KERNEL);
>  	if (!lpc18xx_wdt)
> @@ -216,38 +210,18 @@ static int lpc18xx_wdt_probe(struct platform_device *pdev)
>  	if (IS_ERR(lpc18xx_wdt->base))
>  		return PTR_ERR(lpc18xx_wdt->base);
>  
> -	lpc18xx_wdt->reg_clk = devm_clk_get(dev, "reg");
> +	lpc18xx_wdt->reg_clk = devm_clk_get_enabled(dev, "reg");
>  	if (IS_ERR(lpc18xx_wdt->reg_clk)) {
>  		dev_err(dev, "failed to get the reg clock\n");
>  		return PTR_ERR(lpc18xx_wdt->reg_clk);
>  	}
>  
> -	lpc18xx_wdt->wdt_clk = devm_clk_get(dev, "wdtclk");
> +	lpc18xx_wdt->wdt_clk = devm_clk_get_enabled(dev, "wdtclk");
>  	if (IS_ERR(lpc18xx_wdt->wdt_clk)) {
>  		dev_err(dev, "failed to get the wdt clock\n");
>  		return PTR_ERR(lpc18xx_wdt->wdt_clk);
>  	}
>  
> -	ret = clk_prepare_enable(lpc18xx_wdt->reg_clk);
> -	if (ret) {
> -		dev_err(dev, "could not prepare or enable sys clock\n");
> -		return ret;
> -	}
> -	ret = devm_add_action_or_reset(dev, lpc18xx_clk_disable_unprepare,
> -				       lpc18xx_wdt->reg_clk);
> -	if (ret)
> -		return ret;
> -
> -	ret = clk_prepare_enable(lpc18xx_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, lpc18xx_clk_disable_unprepare,
> -				       lpc18xx_wdt->wdt_clk);
> -	if (ret)
> -		return ret;
> -
>  	/* We use the clock rate to calculate timeouts */
>  	lpc18xx_wdt->clk_rate = clk_get_rate(lpc18xx_wdt->wdt_clk);
>  	if (lpc18xx_wdt->clk_rate == 0) {
> -- 
> 2.34.1
>