linux-kernel - Re: [PATCH RESEND v8 05/10] watchdog: rzg2l_wdt: Remove reset de-assert from probe

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Date: Wed, 10 Apr 2024 09:41:29 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Claudiu <claudiu.beznea@...on.dev>
Cc: wim@...ux-watchdog.org, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, p.zabel@...gutronix.de,
	geert+renesas@...der.be, magnus.damm@...il.com,
	biju.das.jz@...renesas.com, linux-watchdog@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH RESEND v8 05/10] watchdog: rzg2l_wdt: Remove reset
 de-assert from probe

On Wed, Apr 10, 2024 at 04:40:39PM +0300, Claudiu wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> 
> There is no need to de-assert the reset signal on probe as the watchdog
> is not used prior executing start. Also, the clocks are not enabled in
> probe (pm_runtime_enable() doesn't do that), thus this is another indicator
> that the watchdog wasn't used previously like this. Instead, keep the
> watchdog hardware in its previous state at probe (by default it is in
> reset state), enable it when it is started and move it to reset state
> when it is stopped. This saves some extra power when the watchdog is
> unused.
> 
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>

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

> ---
> 
> Changes in v8:
> - none
> 
> Changes in v7:
> - none
> 
> Changes in v6:
> - none
> 
> Changes in v5:
> - update patch title
> 
> Changes in v4:
> - none
> 
> Changes in v3:
> - none
> 
> Changes in v2:
> - none
> 
>  drivers/watchdog/rzg2l_wdt.c | 26 +++++++++++++++-----------
>  1 file changed, 15 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c
> index 7bce093316c4..93a49fd0c7aa 100644
> --- a/drivers/watchdog/rzg2l_wdt.c
> +++ b/drivers/watchdog/rzg2l_wdt.c
> @@ -129,6 +129,10 @@ static int rzg2l_wdt_start(struct watchdog_device *wdev)
>  	if (ret)
>  		return ret;
>  
> +	ret = reset_control_deassert(priv->rstc);
> +	if (ret)
> +		return ret;
> +
>  	/* Initialize time out */
>  	rzg2l_wdt_init_timeout(wdev);
>  
> @@ -146,7 +150,9 @@ static int rzg2l_wdt_stop(struct watchdog_device *wdev)
>  	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
>  	int ret;
>  
> -	rzg2l_wdt_reset(priv);
> +	ret = reset_control_assert(priv->rstc);
> +	if (ret)
> +		return ret;
>  
>  	ret = pm_runtime_put(wdev->parent);
>  	if (ret < 0)
> @@ -186,6 +192,12 @@ static int rzg2l_wdt_restart(struct watchdog_device *wdev,
>  	clk_prepare_enable(priv->osc_clk);
>  
>  	if (priv->devtype == WDT_RZG2L) {
> +		int ret;
> +
> +		ret = reset_control_deassert(priv->rstc);
> +		if (ret)
> +			return ret;
> +
>  		/* Generate Reset (WDTRSTB) Signal on parity error */
>  		rzg2l_wdt_write(priv, 0, PECR);
>  
> @@ -236,13 +248,11 @@ static const struct watchdog_ops rzg2l_wdt_ops = {
>  	.restart = rzg2l_wdt_restart,
>  };
>  
> -static void rzg2l_wdt_reset_assert_pm_disable(void *data)
> +static void rzg2l_wdt_pm_disable(void *data)
>  {
>  	struct watchdog_device *wdev = data;
> -	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
>  
>  	pm_runtime_disable(wdev->parent);
> -	reset_control_assert(priv->rstc);
>  }
>  
>  static int rzg2l_wdt_probe(struct platform_device *pdev)
> @@ -285,10 +295,6 @@ static int rzg2l_wdt_probe(struct platform_device *pdev)
>  		return dev_err_probe(&pdev->dev, PTR_ERR(priv->rstc),
>  				     "failed to get cpg reset");
>  
> -	ret = reset_control_deassert(priv->rstc);
> -	if (ret)
> -		return dev_err_probe(dev, ret, "failed to deassert");
> -
>  	priv->devtype = (uintptr_t)of_device_get_match_data(dev);
>  
>  	if (priv->devtype == WDT_RZV2M) {
> @@ -309,9 +315,7 @@ static int rzg2l_wdt_probe(struct platform_device *pdev)
>  	priv->wdev.timeout = WDT_DEFAULT_TIMEOUT;
>  
>  	watchdog_set_drvdata(&priv->wdev, priv);
> -	ret = devm_add_action_or_reset(&pdev->dev,
> -				       rzg2l_wdt_reset_assert_pm_disable,
> -				       &priv->wdev);
> +	ret = devm_add_action_or_reset(&pdev->dev, rzg2l_wdt_pm_disable, &priv->wdev);
>  	if (ret < 0)
>  		return ret;
>  
> -- 
> 2.39.2
>