Re: [PATCH] watchdog: npcm: fix sleeping clock call in restart handler

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Low] watchdog: npcm: open-coded devm_clk_get_optional_prepared() in
  npcm_wdt_probe()
--

commit d887f7d373bb7c1fa8a0907fd176d60b84597a65
Author: Zhao Feng <zhaofeng2@cmss.chinamobile.com>

watchdog: npcm: fix sleeping clock call in restart handler

This commit prepares the watchdog clock at probe time and registers a devm
cleanup action so that npcm_wdt_restart() can call clk_enable() in atomic
context instead of clk_prepare_enable().

> diff --git a/drivers/watchdog/npcm_wdt.c b/drivers/watchdog/npcm_wdt.c
> index 4d8f212871447..4fb17f758cdbc 100644
> --- a/drivers/watchdog/npcm_wdt.c
> +++ b/drivers/watchdog/npcm_wdt.c

[ ... ]

> @@ -386,6 +390,11 @@ static const struct watchdog_ops npcm_wdt_ops = {
>  	.restart = npcm_wdt_restart,
>  };
>  
> +static void npcm_clk_unprepare(void *data)
> +{
> +	clk_unprepare(data);
> +}
> +
>  static int npcm_wdt_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -414,6 +423,20 @@ static int npcm_wdt_probe(struct platform_device *pdev)
>  	if (IS_ERR(wdt->clk))
>  		return PTR_ERR(wdt->clk);
>  
> +	/*
> +	 * Prepare the clock once and keep it prepared for the lifetime
> +	 * of the driver: npcm_wdt_restart() runs in atomic context and
> +	 * may only call clk_enable().
> +	 */
> +	ret = clk_prepare(wdt->clk);
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_add_action_or_reset(&pdev->dev, npcm_clk_unprepare,
> +				       wdt->clk);
> +	if (ret)
> +		return ret;

[Severity: Low]
Could devm_clk_get_optional_prepared(&pdev->dev, NULL) be used here
instead of open-coding clk_prepare(), devm_add_action_or_reset(), and
npcm_clk_unprepare()?  Also, since wdt->clk now stays prepared for the
lifetime of the driver, npcm_wdt_start() and npcm_wdt_stop() only need
clk_enable() and clk_disable() rather than clk_prepare_enable() and
clk_disable_unprepare().

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261111064150.260-1-zhaofeng2@cmss.chinamobile.com?part=1