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

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Date: Wed, 10 Apr 2024 14:05:30 +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.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 beznea <claudiu.beznea@...on.dev>
> Sent: Wednesday, April 10, 2024 3:02 PM
> Subject: Re: [PATCH RESEND v8 03/10] watchdog: rzg2l_wdt: Use pm_runtime_resume_and_get()
> 
> 
> 
> On 10.04.2024 16:51, Biju Das wrote:
> > 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.
> >
> 
> I'm not sure I got you correctly.
> 
> This patch keeps the previous functionality, thus, if the watchdog is active rzg2l_wdt_stop() is
> called which does a reset assert. Then
> rzg2l_wdt_start() is called which does the reset deassert.

You are correct. I overlooked and thought you have removed *_stop() as well.
Sorry for the noise.

Cheers,
Biju


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