linux-kernel - Re: [PATCH v5 4/5] PM: hibernate: add new api pm_hibernate_is

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Message-ID: <CAJZ5v0hAHfL-Vamh-OAGJ73oVnoRDXh3QqLd8+NjNFsU5yWwcg@mail.gmail.com>
Date: Wed, 9 Jul 2025 12:14:06 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Samuel Zhang <guoqing.zhang@....com>
Cc: alexander.deucher@....com, christian.koenig@....com, rafael@...nel.org, 
	len.brown@...el.com, pavel@...nel.org, gregkh@...uxfoundation.org, 
	dakr@...nel.org, airlied@...il.com, simona@...ll.ch, ray.huang@....com, 
	matthew.auld@...el.com, matthew.brost@...el.com, 
	maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de, 
	mario.limonciello@....com, lijo.lazar@....com, victor.zhao@....com, 
	haijun.chang@....com, Qing.Ma@....com, Owen.Zhang2@....com, 
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v5 4/5] PM: hibernate: add new api pm_hibernate_is_recovering()

On Wed, Jul 9, 2025 at 12:05 PM Samuel Zhang <guoqing.zhang@....com> wrote:
>
> dev_pm_ops.thaw() is called in following cases:
> * normal case: after hibernation image has been created.
> * error case 1: creation of a hibernation image has failed.
> * error case 2: restoration from a hibernation image has failed.
>
> For normal case, it is called mainly for resume storage devices for
> saving the hibernation image. Other devices that are not involved
> in the image saving do not need to resume the device. But since there's
> no api to know which case thaw() is called, device drivers can't
> conditionally resume device in thaw().
>
> The new pm_hibernate_is_recovering() is such a api to query if thaw() is
> called in normal case.
>
> Signed-off-by: Samuel Zhang <guoqing.zhang@....com>
> ---
>  drivers/base/power/main.c | 14 ++++++++++++++
>  include/linux/pm.h        |  2 ++
>  2 files changed, 16 insertions(+)
>
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index 40e1d8d8a589..ff78cf96f795 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -63,6 +63,20 @@ static LIST_HEAD(dpm_noirq_list);
>  static DEFINE_MUTEX(dpm_list_mtx);
>  static pm_message_t pm_transition;
>
> +/**
> + * pm_hibernate_is_recovering - if recovering from hibernate due to error.
> + *
> + * Used to query if dev_pm_ops.thaw() is called for normal hibernation case or
> + * recovering from some error.
> + *
> + * Return: true for error case, false for normal case.
> + */
> +bool pm_hibernate_is_recovering(void)
> +{
> +       return pm_transition.event == PM_EVENT_RECOVER;
> +}
> +EXPORT_SYMBOL_GPL(pm_hibernate_is_recovering);
> +
>  static int async_error;
>
>  static const char *pm_verb(int event)
> diff --git a/include/linux/pm.h b/include/linux/pm.h
> index 78855d794342..f54a803f2afb 100644
> --- a/include/linux/pm.h
> +++ b/include/linux/pm.h
> @@ -657,6 +657,8 @@ struct pm_subsys_data {
>  #define DPM_FLAG_SMART_SUSPEND         BIT(2)
>  #define DPM_FLAG_MAY_SKIP_RESUME       BIT(3)
>
> +bool pm_hibernate_is_recovering(void);
> +

Please add this to suspend.h instead (preferably after the
is_hibernate_resume_dev definition).

>  struct dev_pm_info {
>         pm_message_t            power_state;
>         bool                    can_wakeup:1;
> --