linux-kernel - Re: [PATCH] drivers: core: Detach device from power domain on shutdown

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Date:   Fri, 8 Jan 2021 16:49:58 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Furquan Shaikh <furquan@...gle.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Subject: Re: [PATCH] drivers: core: Detach device from power domain on shutdown

On Fri, Jan 8, 2021 at 4:43 PM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> On Mon, Dec 14, 2020 at 08:56:48PM -0800, Furquan Shaikh wrote:
> > On Tue, Dec 1, 2020 at 1:30 PM Furquan Shaikh <furquan@...gle.com> wrote:
> > >
> > > When the system is powered off or rebooted, devices are not detached
> > > from their PM domain. This results in ACPI PM not being invoked and
> > > hence PowerResouce _OFF method not being invoked for any of the
> > > devices. Because the ACPI power resources are not turned off in case
> > > of poweroff and reboot, it violates the power sequencing requirements
> > > which impacts the reliability of the devices over the lifetime of the
> > > platform. This is currently observed on all Chromebooks using ACPI.
> > >
> > > In order to solve the above problem, this change detaches a device
> > > from its PM domain whenever it is shutdown. This action is basically
> > > analogous to ->remove() from driver model perspective. Detaching the
> > > device from its PM domain ensures that the ACPI PM gets a chance to
> > > turn off the power resources for the device thus complying with its
> > > power sequencing requirements.
> > >
> > > Signed-off-by: Furquan Shaikh <furquan@...gle.com>
> > > ---
> > >  drivers/base/core.c | 3 +++
> > >  1 file changed, 3 insertions(+)
> > >
> > > diff --git a/drivers/base/core.c b/drivers/base/core.c
> > > index d661ada1518f..5823f1d719e1 100644
> > > --- a/drivers/base/core.c
> > > +++ b/drivers/base/core.c
> > > @@ -23,6 +23,7 @@
> > >  #include <linux/of_device.h>
> > >  #include <linux/genhd.h>
> > >  #include <linux/mutex.h>
> > > +#include <linux/pm_domain.h>
> > >  #include <linux/pm_runtime.h>
> > >  #include <linux/netdevice.h>
> > >  #include <linux/sched/signal.h>
> > > @@ -4057,6 +4058,8 @@ void device_shutdown(void)
> > >                         dev->driver->shutdown(dev);
> > >                 }
> > >
> > > +               dev_pm_domain_detach(dev, true);
> > > +
> > >                 device_unlock(dev);
> > >                 if (parent)
> > >                         device_unlock(parent);
> > > --
> > > 2.29.2.454.gaff20da3a2-goog
> > >
> >
> > Hello,
> >
> > Gentle ping. Just checking if there are any comments.
>
> I'll wait for Rafael to ack this before taking it...

Done.

Cheers!