linux-kernel - Re: [PATCH v2] drivers: base: add support to skip power management in device/driver model

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Date:   Thu, 14 Feb 2019 18:34:19 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jisheng Zhang <jszhang@...vell.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        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 v2] drivers: base: add support to skip power management in
 device/driver model

On Thu, Feb 14, 2019 at 1:05 PM Sudeep Holla <sudeep.holla@....com> wrote:
>
> On Thu, Feb 14, 2019 at 11:16:09AM +0000, Sudeep Holla wrote:
> > On Wed, Feb 13, 2019 at 11:17:47PM +0100, Rafael J. Wysocki wrote:
> > > On Wed, Feb 13, 2019 at 1:01 PM Sudeep Holla <sudeep.holla@....com> wrote:
>
> [...]
>
> > > > diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> > > > index 0992e67e862b..2a29c3d4e240 100644
> > > > --- a/drivers/base/power/main.c
> > > > +++ b/drivers/base/power/main.c
> > > > @@ -124,6 +124,10 @@ void device_pm_unlock(void)
> > > >   */
> > > >  void device_pm_add(struct device *dev)
> > > >  {
> > > > +       /* No need to create pm sysfs if explicitly specified as not required */
> > >
> > > Is this really about sysfs?
> > >
> >
> > Nope, copy-paste from dpm_sysfs_add, will drop it.
> >
> > > > +       if (device_pm_not_required(dev))
> > >
> > > Should power.disable_depth be bumped up here or while setting the "no PM" flag?
> > >
> >
> > OK, I missed that.
> >
>
> Looking at it,
> 1. We can't set it when we set "no PM" flag as pm_runtime_init called later
>    initialise it to 1
> 2. We can bump it here, but I see it's usage self contained in runtime.c
>    and may look odd to access it here.
>
> More basic question is should we really need to bump it to 2 as its
> initialised to 1 in runtime_init.

Right, I thought about that.

Let's leave it as is maybe. :-)