linux-kernel - Re: [PATCH] drivers: base: add support to skip power management in device/driver model

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Date:   Mon, 11 Feb 2019 17:20:20 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Jisheng Zhang <jszhang@...vell.com>,
        Steve Longerbeam <slongerbeam@...il.com>,
        Eugeniu Rosca <erosca@...adit-jv.com>,
        Joshua Frkuska <joshua_frkuska@...tor.com>,
        Eugeniu Rosca <roscaeugeniu@...il.com>
Subject: Re: [PATCH] drivers: base: add support to skip power management in
 device/driver model

On Thu, 7 Feb 2019 at 16:29, Sudeep Holla <sudeep.holla@....com> wrote:
>
> On Thu, Feb 07, 2019 at 04:18:57PM +0100, Ulf Hansson wrote:
> > On Thu, 7 Feb 2019 at 16:06, Sudeep Holla <sudeep.holla@....com> wrote:
>
> [...]
>
> > > Indeed, I was ignoring knowing that it's harmless. But more people
> > > started to complain, and Rafael suggested this which I agree as we
> > > have several pseudo devices created in the kernel that we can bypass
> > > some of these pm handling knowing we won't need it.
> >
> > Okay, I see.
> >
> > Anyway, I will likely need to restore part of this change, via my
> > cluster idling series then. As from that point, the cpu device that
> > you call device_set_pm_not_required() for, starts to be used from both
> > PM core and runtime PM point of view. But I guess that's okay then.
> >
>
> Ah I see. I can drop for CPU devices then. Since I didn't see any use for
> them, I set the flag, but I can drop it now or you can do that as part
> of that series.

Well, I prefer if you drop it for CPU devices, as least for now.

> There are quite a few devices(especially the ones
> registered under system subsys can set this but I would take it separate
> once we settle on this). Also Rafael may have seen use for few more
> devices when he suggested this.

Yep, let's find another first user of this.

Additionally, it seems like we should drop the print in device_pm_add().

Kind regards
Uffe