Re: [PATCH v8 1/4] PM: Introduce new PMSG_POWEROFF event

[Bjorn Helgaas <helgaas@kernel.org>]

On Wed, Sep 17, 2025 at 10:44:24PM -0500, Mario Limonciello (AMD) wrote:
> PMSG_POWEROFF will be used for the PM core to allow differentiating between
> a hibernation or shutdown sequence when re-using callbacks.

I think it would be useful to say something here about how the
hibernation and shutdown sequences are entered, e.g., what user
commands and syscalls are related?

> Tested-by: Eric Naim <dnaim@cachyos.org>
> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
> ---
> v8:
>  * Break series into 3 parts
>  * Drop PMSG_NO_WAKEUP change
> v7:
>  * Reword commit
> v5:
>  * Re-order and split
>  * Add tags
> v4:
>  * https://lore.kernel.org/linux-pci/20250616175019.3471583-1-superm1@kernel.org/
> ---
>  drivers/base/power/main.c    | 7 +++++++
>  include/linux/pm.h           | 3 +++
>  include/trace/events/power.h | 3 ++-
>  3 files changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index 2ea6e05e6ec9..86661c94e8ce 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -99,6 +99,8 @@ static const char *pm_verb(int event)
>  		return "restore";
>  	case PM_EVENT_RECOVER:
>  		return "recover";
> +	case PM_EVENT_POWEROFF:
> +		return "poweroff";
>  	default:
>  		return "(unknown PM event)";
>  	}
> @@ -369,6 +371,7 @@ static pm_callback_t pm_op(const struct dev_pm_ops *ops, pm_message_t state)
>  	case PM_EVENT_FREEZE:
>  	case PM_EVENT_QUIESCE:
>  		return ops->freeze;
> +	case PM_EVENT_POWEROFF:
>  	case PM_EVENT_HIBERNATE:
>  		return ops->poweroff;
>  	case PM_EVENT_THAW:
> @@ -403,6 +406,7 @@ static pm_callback_t pm_late_early_op(const struct dev_pm_ops *ops,
>  	case PM_EVENT_FREEZE:
>  	case PM_EVENT_QUIESCE:
>  		return ops->freeze_late;
> +	case PM_EVENT_POWEROFF:
>  	case PM_EVENT_HIBERNATE:
>  		return ops->poweroff_late;
>  	case PM_EVENT_THAW:
> @@ -437,6 +441,7 @@ static pm_callback_t pm_noirq_op(const struct dev_pm_ops *ops, pm_message_t stat
>  	case PM_EVENT_FREEZE:
>  	case PM_EVENT_QUIESCE:
>  		return ops->freeze_noirq;
> +	case PM_EVENT_POWEROFF:
>  	case PM_EVENT_HIBERNATE:
>  		return ops->poweroff_noirq;
>  	case PM_EVENT_THAW:
> @@ -1370,6 +1375,8 @@ static pm_message_t resume_event(pm_message_t sleep_state)
>  		return PMSG_RECOVER;
>  	case PM_EVENT_HIBERNATE:
>  		return PMSG_RESTORE;
> +	case PM_EVENT_POWEROFF:
> +		return PMSG_ON;
>  	}
>  	return PMSG_ON;
>  }
> diff --git a/include/linux/pm.h b/include/linux/pm.h
> index cc7b2dc28574..d001224c92fd 100644
> --- a/include/linux/pm.h
> +++ b/include/linux/pm.h
> @@ -507,6 +507,7 @@ const struct dev_pm_ops name = { \
>   * RECOVER	Creation of a hibernation image or restoration of the main
>   *		memory contents from a hibernation image has failed, call
>   *		->thaw() and ->complete() for all devices.

Looks like there should be a blank line here to match formatting of
other messages.

> + * POWEROFF	System will poweroff, call ->poweroff() for all devices.
>   *
>   * The following PM_EVENT_ messages are defined for internal use by
>   * kernel subsystems.  They are never issued by the PM core.
> @@ -537,6 +538,7 @@ const struct dev_pm_ops name = { \
>  #define PM_EVENT_USER		0x0100
>  #define PM_EVENT_REMOTE		0x0200
>  #define PM_EVENT_AUTO		0x0400
> +#define PM_EVENT_POWEROFF	0x0800
>  
>  #define PM_EVENT_SLEEP		(PM_EVENT_SUSPEND | PM_EVENT_HIBERNATE)
>  #define PM_EVENT_USER_SUSPEND	(PM_EVENT_USER | PM_EVENT_SUSPEND)
> @@ -551,6 +553,7 @@ const struct dev_pm_ops name = { \
>  #define PMSG_QUIESCE	((struct pm_message){ .event = PM_EVENT_QUIESCE, })
>  #define PMSG_SUSPEND	((struct pm_message){ .event = PM_EVENT_SUSPEND, })
>  #define PMSG_HIBERNATE	((struct pm_message){ .event = PM_EVENT_HIBERNATE, })
> +#define PMSG_POWEROFF	((struct pm_message){ .event = PM_EVENT_POWEROFF, })
>  #define PMSG_RESUME	((struct pm_message){ .event = PM_EVENT_RESUME, })
>  #define PMSG_THAW	((struct pm_message){ .event = PM_EVENT_THAW, })
>  #define PMSG_RESTORE	((struct pm_message){ .event = PM_EVENT_RESTORE, })
> diff --git a/include/trace/events/power.h b/include/trace/events/power.h
> index 82904291c2b8..370f8df2fdb4 100644
> --- a/include/trace/events/power.h
> +++ b/include/trace/events/power.h
> @@ -179,7 +179,8 @@ TRACE_EVENT(pstate_sample,
>  		{ PM_EVENT_HIBERNATE, "hibernate" }, \
>  		{ PM_EVENT_THAW, "thaw" }, \
>  		{ PM_EVENT_RESTORE, "restore" }, \
> -		{ PM_EVENT_RECOVER, "recover" })
> +		{ PM_EVENT_RECOVER, "recover" }, \
> +		{ PM_EVENT_POWEROFF, "poweroff" })
>  
>  DEFINE_EVENT(cpu, cpu_frequency,
>  
> -- 
> 2.51.0
>