linux-kernel - RE: [PATCH v3 6/8] pwm: rzg2l-gpt: Add suspend/resume support

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Message-ID:
 <TY3PR01MB11346F105FD6CCE1167F9095686DBA@TY3PR01MB11346.jpnprd01.prod.outlook.com>
Date: Mon, 1 Dec 2025 15:50:09 +0000
From: Biju Das <biju.das.jz@...renesas.com>
To: Uwe Kleine-König <ukleinek@...nel.org>
CC: biju.das.au <biju.das.au@...il.com>, Philipp Zabel
	<p.zabel@...gutronix.de>, "linux-pwm@...r.kernel.org"
	<linux-pwm@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, Geert Uytterhoeven <geert+renesas@...der.be>,
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>,
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
Subject: RE: [PATCH v3 6/8] pwm: rzg2l-gpt: Add suspend/resume support

Hi Uwe,

> -----Original Message-----
> From: Uwe Kleine-König <ukleinek@...nel.org>
> Sent: 01 December 2025 15:29
> Subject: Re: [PATCH v3 6/8] pwm: rzg2l-gpt: Add suspend/resume support
> 
> Hello Biju,
> 
> On Mon, Dec 01, 2025 at 03:04:08PM +0000, Biju Das wrote:
> > You mean to avoid unbalance between suspend()/resume(), we should not
> > do error handling in resume()??
> 
> Consider the following resume function:
> 
> 	static int myresume(...)
> 	{
> 		ret = enable_some_resource(...);
> 		if (ret)
> 			return ret;
> 
> 		ret = enable_some_other_resource(...)
> 		if (ret) {
> 			disable_some_resource();
> 			return ret;
> 
> 		}
> 
> 		return 0;
> 	}
> 
> If disable_some_resource() can fail it might happen that the first call to myresume() is left with
> some_resource enabled and some_other_resource disabled (i.e. if both enable_some_other_resource() and
> disable_some_resource() fail). Now if the resume is retried some_resource is enabled a second time
> without being tracked and a later suspend (or remove) won't bring the enable count to 0 and thus leak
> a resource.

OK, what about for making balanced usage count for suspend()/resume() to avoid resource 
like below

static int myresume(...)
{
	ret = enable_some_resource(...);
	ret |= enable_some_other_resource(...);

	return ret;
}

static int mysuspend(...)
{
	disable_some_resource(...);
	disable_some_other_resource(...)

	return 0;
}