linux-kernel - Re: [PATCH] cpufreq: suspend/resume governors with PM notifiers

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Message-ID: <2123322.DfAe1RTUPo@vostro.rjw.lan>
Date:	Mon, 25 Nov 2013 12:35:44 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	Lists linaro-kernel <linaro-kernel@...ts.linaro.org>,
	Patch Tracking <patches@...aro.org>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Lan Tianyu <tianyu.lan@...el.com>, Nishanth Menon <nm@...com>,
	jinchoi@...adcom.com,
	Sebastian Capella <sebastian.capella@...aro.org>,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Subject: Re: [PATCH] cpufreq: suspend/resume governors with PM notifiers

On Monday, November 25, 2013 09:55:19 AM Viresh Kumar wrote:
> On 22 November 2013 14:41, viresh kumar <viresh.kumar@...aro.org> wrote:
> > So, what about something like this ?
> >
> > diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
> > index f48370d..523c0bc 100644
> > --- a/drivers/base/cpu.c
> > +++ b/drivers/base/cpu.c
> > @@ -120,6 +120,45 @@ static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
> >  #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
> >  #endif /* CONFIG_HOTPLUG_CPU */
> >
> > +int cpu_subsys_suspend_noirq(struct device *dev)
> > +{
> > +       struct bus_type *bus = dev->bus;
> > +       struct subsys_interface *sif;
> > +       int ret = 0;
> > +
> > +       list_for_each_entry(sif, &bus->p->interfaces, node) {
> > +               if (sif->pm && sif->pm->suspend_noirq) {
> > +                       ret = sif->suspend_noirq(dev);
> > +                       if (ret)
> > +                               break;
> > +               }
> > +       }
> > +
> > +       return ret;
> > +}
> > +
> > +int cpu_subsys_resume_noirq(struct device *dev)
> > +{
> > +       struct bus_type *bus = dev->bus;
> > +       struct subsys_interface *sif;
> > +       int ret = 0;
> > +
> > +       list_for_each_entry(sif, &bus->p->interfaces, node) {
> > +               if (sif->pm && sif->pm->resume_noirq) {
> > +                       ret = sif->resume_noirq(dev);
> > +                       if (ret)
> > +                               break;
> > +               }
> > +       }
> > +
> > +       return ret;
> > +}
> > +
> > +static const struct dev_pm_ops cpu_subsys_pm_ops = {
> > +       .suspend_noirq = cpu_subsys_suspend_noirq,
> > +       .resume_noirq = cpu_subsys_resume_noirq,
> > +};
> > +
> >  struct bus_type cpu_subsys = {
> >         .name = "cpu",
> >         .dev_name = "cpu",
> > @@ -128,6 +167,7 @@ struct bus_type cpu_subsys = {
> >         .online = cpu_subsys_online,
> >         .offline = cpu_subsys_offline,
> >  #endif
> > +       .pm = &cpu_subsys_pm_ops,
> >  };
> >  EXPORT_SYMBOL_GPL(cpu_subsys);
> >
> > diff --git a/include/linux/device.h b/include/linux/device.h
> > index b025925..fa01273 100644
> > --- a/include/linux/device.h
> > +++ b/include/linux/device.h
> > @@ -298,11 +298,16 @@ struct device *driver_find_device(struct device_driver *drv,
> >   * @node:       the list of functions registered at the subsystem
> >   * @add_dev:    device hookup to device function handler
> >   * @remove_dev: device hookup to device function handler
> > + * @pm: Power management operations of this interface.
> >   *
> >   * Simple interfaces attached to a subsystem. Multiple interfaces can
> >   * attach to a subsystem and its devices. Unlike drivers, they do not
> >   * exclusively claim or control devices. Interfaces usually represent
> >   * a specific functionality of a subsystem/class of devices.
> > + *
> > + * PM callbacks are called from individual subsystems instead of PM core. And
> > + * hence might not be available for all subsystems. Currently present for:
> > + * cpu_subsys.
> >   */
> >  struct subsys_interface {
> >         const char *name;
> > @@ -310,6 +315,7 @@ struct subsys_interface {
> >         struct list_head node;
> >         int (*add_dev)(struct device *dev, struct subsys_interface *sif);
> >         int (*remove_dev)(struct device *dev, struct subsys_interface *sif);
> > +       const struct dev_pm_ops *pm;
> >  };
> >
> >  int subsys_interface_register(struct subsys_interface *sif);
> 
> Any inputs?

Please give me some more time, this suretly is not urgent?

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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