linux-kernel - RE: [PATCH v9 3/9] watchdog: rzg2l_wdt: Use pm_runtime_resume_and

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Message-ID:
 <TY3PR01MB11346FEA45BED2B843076F8FB86DA2@TY3PR01MB11346.jpnprd01.prod.outlook.com>
Date: Mon, 8 Jul 2024 05:46:56 +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 v9 3/9] watchdog: rzg2l_wdt: Use
 pm_runtime_resume_and_get()

Hi Claudiu,

> -----Original Message-----
> From: Claudiu <claudiu.beznea@...on.dev>
> Sent: Friday, May 31, 2024 7:57 AM
> Subject: [PATCH v9 3/9] 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>
> Reviewed-by: Guenter Roeck <linux@...ck-us.net>
> ---
> 
> Changes in v9:
> - collected Guenter's Rb tag
> 
> 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;

Checking ret will lead to imbalance. It should be ret < 0 as ret = 1 corresponds to RPM_ACTIVE and the API does not call put() when ret = 1; see [1] and [2]

[1] https://elixir.bootlin.com/linux/v6.10-rc6/source/drivers/base/power/runtime.c#L778

[2] https://elixir.bootlin.com/linux/v6.10-rc6/source/include/linux/pm_runtime.h#L431

Cheers,
Biju