Re: [PATCH 2/4] watchdog: rzg2l_wdt: Add error check for reset_control_{deassert/reset}

[Guenter Roeck <linux@xxxxxxxxxxxx>]

On 12/11/21 1:26 PM, Biju Das wrote:
> If reset_control_deassert()/reset_control_reset() fails, then we
> won't be able to access the device registers. Therefore check the
> return code of reset_control_deassert()/reset_control_reset() and
> return the error code to caller in case of error.
>
> While at it remove the unnecessary pm_runtime_resume_and_get()
> from probe(), as it turns on the clocks.
>
> Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>

Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>

See note below, though.

> ---
>   drivers/watchdog/rzg2l_wdt.c | 37 +++++++++++++++++++-----------------
>   1 file changed, 20 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c
> index 96f2a018ab62..58fe4efd9a89 100644
> --- a/drivers/watchdog/rzg2l_wdt.c
> +++ b/drivers/watchdog/rzg2l_wdt.c
> @@ -85,8 +85,14 @@ static void rzg2l_wdt_init_timeout(struct watchdog_device *wdev)
>   static int rzg2l_wdt_start(struct watchdog_device *wdev)
>   {
>   	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +	int ret;
> +
> +	ret = reset_control_deassert(priv->rstc);
> +	if (ret) {
> +		dev_err(wdev->parent, "failed to deassert");
> +		return ret;
> +	}
>   
This patch introduces an error return into rzg2l_wdt_start().
If it is indeed necessary to call this function when setting
the timeout, the error return needs to be checked there.

Guenter

> -	reset_control_deassert(priv->rstc);
>   	pm_runtime_get_sync(wdev->parent);
>   
>   	/* Initialize time out */
> @@ -115,9 +121,15 @@ static int rzg2l_wdt_restart(struct watchdog_device *wdev,
>   			     unsigned long action, void *data)
>   {
>   	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +	int ret;
>   
>   	/* Reset the module before we modify any register */
> -	reset_control_reset(priv->rstc);
> +	ret = reset_control_reset(priv->rstc);
> +	if (ret) {
> +		dev_err(wdev->parent, "failed to reset");
> +		return ret;
> +	}
> +
>   	pm_runtime_get_sync(wdev->parent);
>   
>   	/* smallest counter value to reboot soon */
> @@ -151,12 +163,11 @@ static const struct watchdog_ops rzg2l_wdt_ops = {
>   	.restart = rzg2l_wdt_restart,
>   };
>   
> -static void rzg2l_wdt_reset_assert_pm_disable_put(void *data)
> +static void rzg2l_wdt_reset_assert_pm_disable(void *data)
>   {
>   	struct watchdog_device *wdev = data;
>   	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
>   
> -	pm_runtime_put(wdev->parent);
>   	pm_runtime_disable(wdev->parent);
>   	reset_control_assert(priv->rstc);
>   }
> @@ -204,13 +215,11 @@ static int rzg2l_wdt_probe(struct platform_device *pdev)
>   		return dev_err_probe(&pdev->dev, PTR_ERR(priv->rstc),
>   				     "failed to get cpg reset");
>   
> -	reset_control_deassert(priv->rstc);
> +	ret = reset_control_deassert(priv->rstc);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to deassert");
> +
>   	pm_runtime_enable(&pdev->dev);
> -	ret = pm_runtime_resume_and_get(&pdev->dev);
> -	if (ret < 0) {
> -		dev_err(dev, "pm_runtime_resume_and_get failed ret=%pe", ERR_PTR(ret));
> -		goto out_pm_get;
> -	}
>   
>   	priv->wdev.info = &rzg2l_wdt_ident;
>   	priv->wdev.ops = &rzg2l_wdt_ops;
> @@ -222,7 +231,7 @@ static int rzg2l_wdt_probe(struct platform_device *pdev)
>   
>   	watchdog_set_drvdata(&priv->wdev, priv);
>   	ret = devm_add_action_or_reset(&pdev->dev,
> -				       rzg2l_wdt_reset_assert_pm_disable_put,
> +				       rzg2l_wdt_reset_assert_pm_disable,
>   				       &priv->wdev);
>   	if (ret < 0)
>   		return ret;
> @@ -235,12 +244,6 @@ static int rzg2l_wdt_probe(struct platform_device *pdev)
>   		dev_warn(dev, "Specified timeout invalid, using default");
>   
>   	return devm_watchdog_register_device(&pdev->dev, &priv->wdev);
> -
> -out_pm_get:
> -	pm_runtime_disable(dev);
> -	reset_control_assert(priv->rstc);
> -
> -	return ret;
>   }
>   
>   static const struct of_device_id rzg2l_wdt_ids[] = {