linux-kernel - Re: [PATCH 1/2] ACPI / PM: Use register_reboot_notifier() instead of pm_power_off

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Date:   Wed, 21 Mar 2018 15:04:23 +0100
From:   Pavel Machek <pavel@....cz>
To:     Baolin Wang <baolin.wang@...aro.org>
Cc:     rjw@...ysocki.net, lenb@...nel.org, andrew.smirnov@...il.com,
        akpm@...ux-foundation.org, broonie@...nel.org, arnd@...db.de,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH 1/2] ACPI / PM: Use register_reboot_notifier() instead of
 pm_power_off_prepare

On Wed 2018-03-21 19:30:16, Baolin Wang wrote:
> We can register one notifier through register_reboot_notifier() function to
> prepare to power off the system, then we can remove the 'pm_power_off_prepare'
> hook in following patch.
> 
> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
> ---
> Note: Please help to review carefully, since I have no platform to test
> this conversion.
> 
> I saw there is another reboot notifier in this driver, I am not sure the
> orders between them. I can change the priority of notifier to keep their
> orders if it is necessary.

I don't understand why this is good idea... and you should really test
it. I'm sure you can find PC or notebook somewhere...
								Pavel

>  drivers/acpi/sleep.c |   22 ++++++++++++++++------
>  1 file changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
> index 46cde091..b3de894 100644
> --- a/drivers/acpi/sleep.c
> +++ b/drivers/acpi/sleep.c
> @@ -1229,14 +1229,24 @@ static void acpi_sleep_hibernate_setup(void)
>  static inline void acpi_sleep_hibernate_setup(void) {}
>  #endif /* !CONFIG_HIBERNATION */
>  
> -static void acpi_power_off_prepare(void)
> +static int acpi_reboot_notify(struct notifier_block *this, unsigned long code,
> +			      void *x)
>  {
> -	/* Prepare to power off the system */
> -	acpi_sleep_prepare(ACPI_STATE_S5);
> -	acpi_disable_all_gpes();
> -	acpi_os_wait_events_complete();
> +	if (code == SYSTEM_POWER_OFF) {
> +		/* Prepare to power off the system */
> +		acpi_sleep_prepare(ACPI_STATE_S5);
> +		acpi_disable_all_gpes();
> +		acpi_os_wait_events_complete();
> +	}
> +
> +	return NOTIFY_DONE;
>  }
>  
> +static struct notifier_block acpi_reboot_notifier = {
> +	.notifier_call	= acpi_reboot_notify,
> +	.priority	= 0,
> +};
> +
>  static void acpi_power_off(void)
>  {
>  	/* acpi_sleep_prepare(ACPI_STATE_S5) should have already been called */
> @@ -1261,7 +1271,7 @@ int __init acpi_sleep_init(void)
>  
>  	if (acpi_sleep_state_supported(ACPI_STATE_S5)) {
>  		sleep_states[ACPI_STATE_S5] = 1;
> -		pm_power_off_prepare = acpi_power_off_prepare;
> +		register_reboot_notifier(&acpi_reboot_notifier);
>  		pm_power_off = acpi_power_off;
>  	} else {
>  		acpi_no_s5 = true;

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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