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

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Message-ID: <CAEGmHFGZM0mADs-Eiz780RHzyf3emJinSAMT6ipRMpOvb+HGjg@mail.gmail.com>
Date:   Mon, 14 Dec 2020 20:56:48 -0800
From:   Furquan Shaikh <furquan@...gle.com>
To:     "Rafael J . Wysocki" <rafael@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.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 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.

Thanks,
Furquan