linux-kernel - Re: [PATCH] ACPI/Battery: Accelerate battery resume callback

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Date:	Tue, 20 May 2014 00:54:24 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Lan Tianyu <tianyu.lan@...el.com>
Cc:	lenb@...nel.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ACPI/Battery: Accelerate battery resume callback

On Sunday, May 04, 2014 02:07:06 PM Lan Tianyu wrote:
> Most time of battery resume callback is spent on executing AML code
> _BTP, _BIF and _BIF to get battery info, status and set alarm. These
> AML methods may access EC operation regions several times and consumes
> time.
> 
> These operations are not necessary during devices resume and can run
> during POST_SUSPEND/HIBERNATION event when all processes are thawed.
> 
> This also can avoid removing and adding battery sysfs nodes every system
> resume even if the battery unit is not actually changed. The original code
> updates sysfs nodes without check and this seems not reasonable.
> 
> Signed-off-by: Lan Tianyu <tianyu.lan@...el.com>

Queued up for 3.16, thanks!

> ---
> This patch is to base on the linux pm tree linux-next branch with
> patches "ACPI: Revert "ACPI / Battery: Remove battery's proc directory""
> and "ACPI: Revert "ACPI: Remove CONFIG_ACPI_PROCFS_POWER and cm_sbsc.c"".
> 
>  drivers/acpi/battery.c | 36 +++++++++++++++++++++++++++---------
>  1 file changed, 27 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
> index 6e7b2a1..3b4921e 100644
> --- a/drivers/acpi/battery.c
> +++ b/drivers/acpi/battery.c
> @@ -696,7 +696,7 @@ static void acpi_battery_quirks(struct acpi_battery *battery)
>  	}
>  }
>  
> -static int acpi_battery_update(struct acpi_battery *battery)
> +static int acpi_battery_update(struct acpi_battery *battery, bool resume)
>  {
>  	int result, old_present = acpi_battery_present(battery);
>  	result = acpi_battery_get_status(battery);
> @@ -707,6 +707,10 @@ static int acpi_battery_update(struct acpi_battery *battery)
>  		battery->update_time = 0;
>  		return 0;
>  	}
> +
> +	if (resume)
> +		return 0;
> +
>  	if (!battery->update_time ||
>  	    old_present != acpi_battery_present(battery)) {
>  		result = acpi_battery_get_info(battery);
> @@ -915,7 +919,7 @@ static print_func acpi_print_funcs[ACPI_BATTERY_NUMFILES] = {
>  static int acpi_battery_read(int fid, struct seq_file *seq)
>  {
>  	struct acpi_battery *battery = seq->private;
> -	int result = acpi_battery_update(battery);
> +	int result = acpi_battery_update(battery, false);
>  	return acpi_print_funcs[fid](seq, result);
>  }
>  
> @@ -1030,7 +1034,7 @@ static void acpi_battery_notify(struct acpi_device *device, u32 event)
>  	old = battery->bat.dev;
>  	if (event == ACPI_BATTERY_NOTIFY_INFO)
>  		acpi_battery_refresh(battery);
> -	acpi_battery_update(battery);
> +	acpi_battery_update(battery, false);
>  	acpi_bus_generate_netlink_event(device->pnp.device_class,
>  					dev_name(&device->dev), event,
>  					acpi_battery_present(battery));
> @@ -1045,13 +1049,27 @@ static int battery_notify(struct notifier_block *nb,
>  {
>  	struct acpi_battery *battery = container_of(nb, struct acpi_battery,
>  						    pm_nb);
> +	int result;
> +
>  	switch (mode) {
>  	case PM_POST_HIBERNATION:
>  	case PM_POST_SUSPEND:
> -		if (battery->bat.dev) {
> -			sysfs_remove_battery(battery);
> -			sysfs_add_battery(battery);
> -		}
> +		if (!acpi_battery_present(battery))
> +			return 0;
> +
> +		if (!battery->bat.dev) {
> +			result = acpi_battery_get_info(battery);
> +			if (result)
> +				return result;
> +
> +			result = sysfs_add_battery(battery);
> +			if (result)
> +				return result;
> +		} else
> +			acpi_battery_refresh(battery);
> +
> +		acpi_battery_init_alarm(battery);
> +		acpi_battery_get_state(battery);
>  		break;
>  	}
>  
> @@ -1087,7 +1105,7 @@ static int acpi_battery_add(struct acpi_device *device)
>  	mutex_init(&battery->sysfs_lock);
>  	if (acpi_has_method(battery->device->handle, "_BIX"))
>  		set_bit(ACPI_BATTERY_XINFO_PRESENT, &battery->flags);
> -	result = acpi_battery_update(battery);
> +	result = acpi_battery_update(battery, false);
>  	if (result)
>  		goto fail;
>  #ifdef CONFIG_ACPI_PROCFS_POWER
> @@ -1149,7 +1167,7 @@ static int acpi_battery_resume(struct device *dev)
>  		return -EINVAL;
>  
>  	battery->update_time = 0;
> -	acpi_battery_update(battery);
> +	acpi_battery_update(battery, true);
>  	return 0;
>  }
>  #else
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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