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 17:01:44 +0300
From: claudiu beznea <claudiu.beznea@...on.dev>
To: Biju Das <biju.das.jz@...renesas.com>,
 "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()



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.

Thank you,
Claudiu Beznea

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