linux-kernel - Re: [PATCH v2 1/2] PM: domains: Add devres variant for dev_pm_domain

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Message-ID: <CAPDyKFoQYTNBhtBXY-Ds7E0TohtA6558W1Jf3cLsnXDQC74DSg@mail.gmail.com>
Date: Wed, 28 May 2025 18:04:45 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Claudiu Beznea <claudiu.beznea@...on.dev>
Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>, gregkh@...uxfoundation.org, 
	rafael@...nel.org, dakr@...nel.org, len.brown@...el.com, pavel@...nel.org, 
	jic23@...nel.org, daniel.lezcano@...aro.org, linux-kernel@...r.kernel.org, 
	linux-pm@...r.kernel.org, linux-iio@...r.kernel.org, 
	linux-renesas-soc@...r.kernel.org, bhelgaas@...gle.com, geert@...ux-m68k.org, 
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH v2 1/2] PM: domains: Add devres variant for dev_pm_domain_attach()

[...]

> >> +/**
> >> + * devm_pm_domain_attach - devres-enabled version of dev_pm_domain_attach()
> >> + * @dev: Device to attach.
> >> + * @attach_power_on: Use to indicate whether we should power on the device
> >> + *                   when attaching (true indicates the device is powered on
> >> + *                   when attaching).
> >> + * @detach_power_off: Used to indicate whether we should power off the device
> >> + *                    when detaching (true indicates the device is powered off
> >> + *                    when detaching).
> >> + *
> >> + * NOTE: this will also handle calling dev_pm_domain_detach() for
> >> + * you during remove phase.
> >> + *
> >> + * Returns 0 on successfully attached PM domain, or a negative error code in
> >> + * case of a failure.
> >> + */
> >> +int devm_pm_domain_attach(struct device *dev, bool attach_power_on,
> >> +                      bool detach_power_off)
> >
> > Do we have examples where we power on a device and leave it powered on
> > (or do not power on device on attach but power off it on detach)? I
>
> I haven't found one yet.
>
> > believe devm release should strictly mirror the acquisition, so separate
> > flag is not needed.
>
> I was in the middle whether I should do it with 2 flags or only to revert
> the acquisition.
>
> >
> >
> >> +{
> >> +    int ret;
> >> +
> >> +    ret = dev_pm_domain_attach(dev, attach_power_on);
> >> +    if (ret)
> >> +            return ret;
> >> +
> >> +    if (detach_power_off)
> >> +            return devm_add_action_or_reset(dev, devm_pm_domain_detach_off,
> >> +                                            dev);
> >> +
> >> +    return devm_add_action_or_reset(dev, devm_pm_domain_detach_on, dev);
> >
> > Instead of 2 separate cleanup methods maybe define dedicated devres:
> >
> > struct dev_pm_domain_devres {
> >       struct device *dev;
> >       bool power_off;
> > }
> >
> > ?
>
> That was the other option I've thought about but I found the one with 2
> cleanup methods to be simpler. What would you prefer here?
>
> Ulf: could you please let me know what would you prefer here?

As it looks like we agreed to use one cleanup method, the struct
dev_pm_domain_devres seems superfluous to me.

[...]

Kind regards
Uffe