linux-kernel - Re: [PATCH 1/2] watchdog: rzg2l_wdt: Issue a reset before we put the PM clocks

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Message-ID: <88eb9941-7bf4-3220-ff8a-7e9b3f4bb01b@roeck-us.net>
Date:   Mon, 28 Nov 2022 20:53:27 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Biju Das <biju.das.jz@...renesas.com>,
        linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
        Chris Paterson <Chris.Paterson2@...esas.com>,
        Biju Das <biju.das@...renesas.com>,
        linux-renesas-soc@...r.kernel.org,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Jacopo Mondi <jacopo@...ndi.org>
Subject: Re: [PATCH 1/2] watchdog: rzg2l_wdt: Issue a reset before we put the
 PM clocks

On 11/17/22 03:49, Fabrizio Castro wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> 
> On RZ/Five SoC it was observed that setting timeout (to say 1 sec) wouldn't
> reset the system.
> 
> The procedure described in the HW manual (Procedure for Activating Modules)
> for activating the target module states we need to start supply of the
> clock module before applying the reset signal. This patch makes sure we
> follow the same procedure to clear the registers of the WDT module, fixing
> the issues seen on RZ/Five SoC.
> 
> While at it re-used rzg2l_wdt_stop() in rzg2l_wdt_set_timeout() as it has
> the same function calls.
> 
> Fixes: 4055ee81009e ("watchdog: rzg2l_wdt: Add set_timeout callback")
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>

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

> ---
>   drivers/watchdog/rzg2l_wdt.c | 10 ++++------
>   1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c
> index 974a4194a8fd..ceca42db0837 100644
> --- a/drivers/watchdog/rzg2l_wdt.c
> +++ b/drivers/watchdog/rzg2l_wdt.c
> @@ -115,25 +115,23 @@ static int rzg2l_wdt_stop(struct watchdog_device *wdev)
>   {
>   	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
>   
> -	pm_runtime_put(wdev->parent);
>   	reset_control_reset(priv->rstc);
> +	pm_runtime_put(wdev->parent);
>   
>   	return 0;
>   }
>   
>   static int rzg2l_wdt_set_timeout(struct watchdog_device *wdev, unsigned int timeout)
>   {
> -	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
> -
>   	wdev->timeout = timeout;
>   
>   	/*
>   	 * If the watchdog is active, reset the module for updating the WDTSET
> -	 * register so that it is updated with new timeout values.
> +	 * register by calling rzg2l_wdt_stop() (which internally calls reset_control_reset()
> +	 * to reset the module) so that it is updated with new timeout values.
>   	 */
>   	if (watchdog_active(wdev)) {
> -		pm_runtime_put(wdev->parent);
> -		reset_control_reset(priv->rstc);
> +		rzg2l_wdt_stop(wdev);
>   		rzg2l_wdt_start(wdev);
>   	}
>