linux-kernel - RE: [PATCH RESEND v8 03/10] watchdog: rzg2l_wdt: Use pm_runtime_resume_and

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Message-ID:
 <OSAPR01MB15874891F67AAFAA955A186886062@OSAPR01MB1587.jpnprd01.prod.outlook.com>
Date: Wed, 10 Apr 2024 13:51:27 +0000
From: Biju Das <biju.das.jz@...renesas.com>
To: Claudiu.Beznea <claudiu.beznea@...on.dev>, "wim@...ux-watchdog.org"
	<wim@...ux-watchdog.org>, "linux@...ck-us.net" <linux@...ck-us.net>,
	"robh@...nel.org" <robh@...nel.org>, "krzk+dt@...nel.org"
	<krzk+dt@...nel.org>, "conor+dt@...nel.org" <conor+dt@...nel.org>,
	"p.zabel@...gutronix.de" <p.zabel@...gutronix.de>, "geert+renesas@...der.be"
	<geert+renesas@...der.be>, "magnus.damm@...il.com" <magnus.damm@...il.com>
CC: "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
	Claudiu.Beznea <claudiu.beznea@...on.dev>, Claudiu Beznea
	<claudiu.beznea.uj@...renesas.com>
Subject: RE: [PATCH RESEND v8 03/10] watchdog: rzg2l_wdt: Use
 pm_runtime_resume_and_get()

Hi Claudiu,

> -----Original Message-----
> From: Claudiu <claudiu.beznea@...on.dev>
> Sent: Wednesday, April 10, 2024 2:41 PM
> Subject: [PATCH RESEND v8 03/10] watchdog: rzg2l_wdt: Use pm_runtime_resume_and_get()
> 
> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> 
> pm_runtime_get_sync() may return with error. In case it returns with error
> dev->power.usage_count needs to be decremented.
> dev->pm_runtime_resume_and_get()
> takes care of this. Thus use it.
> 
> Along with it the rzg2l_wdt_set_timeout() function was updated to propagate the result of
> rzg2l_wdt_start() to its caller.
> 
> Fixes: 2cbc5cd0b55f ("watchdog: Add Watchdog Timer driver for RZ/G2L")
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> ---
> 
> Changes in v8:
> - none
> 
> Changes in v7:
> - none
> 
> Changes in v6:
> - none
> 
> Changes in v5:
> - none
> 
> Changes in v4:
> - none
> 
> Changes in v3:
> - none
> 
> Changes in v2:
> - propagate the return code of rzg2l_wdt_start() to it's callers
> 
> 
>  drivers/watchdog/rzg2l_wdt.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c index
> 1741f98ca67c..d87d4f50180c 100644
> --- a/drivers/watchdog/rzg2l_wdt.c
> +++ b/drivers/watchdog/rzg2l_wdt.c
> @@ -123,8 +123,11 @@ 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;
> 
> -	pm_runtime_get_sync(wdev->parent);
> +	ret = pm_runtime_resume_and_get(wdev->parent);
> +	if (ret)
> +		return ret;
> 
>  	/* Initialize time out */
>  	rzg2l_wdt_init_timeout(wdev);
> @@ -150,6 +153,8 @@ static int rzg2l_wdt_stop(struct watchdog_device *wdev)
> 
>  static int rzg2l_wdt_set_timeout(struct watchdog_device *wdev, unsigned int timeout)  {
> +	int ret = 0;
> +
>  	wdev->timeout = timeout;
> 
>  	/*
> @@ -159,10 +164,10 @@ static int rzg2l_wdt_set_timeout(struct watchdog_device *wdev, unsigned int
> time
>  	 */
>  	if (watchdog_active(wdev)) {
>  		rzg2l_wdt_stop(wdev);
> -		rzg2l_wdt_start(wdev);
> +		ret = rzg2l_wdt_start(wdev);

This IP won't be able to update WDT settings once you have set it.

But we can update it, if we do a reset assert followed by deassert.
So the previous code looks correct to me.

Current case is if the WDT is active, then start it. Maybe I ma missing something here.

Cheers,
Biju

>  	}
> 
> -	return 0;
> +	return ret;
>  }
> 
>  static int rzg2l_wdt_restart(struct watchdog_device *wdev,
> --
> 2.39.2