ACPI battery: only refresh the sysfs files when pertinent information changes
authorAndy Whitcroft <apw@canonical.com>
Thu, 3 May 2012 13:48:26 +0000 (14:48 +0100)
committerLen Brown <len.brown@intel.com>
Tue, 8 May 2012 05:49:57 +0000 (01:49 -0400)
We only need to regenerate the sysfs files when the capacity units
change, avoid the update otherwise.

The origin of this issue is dates way back to 2.6.38:
da8aeb92d4853f37e281f11fddf61f9c7d84c3cd
(ACPI / Battery: Update information on info notification and resume)

cc: <stable@vger.kernel.org>
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Tested-by: Ralf Jung <post@ralfj.de>
Signed-off-by: Len Brown <len.brown@intel.com>
drivers/acpi/battery.c

index 86933ca..7dd3f9f 100644 (file)
@@ -643,11 +643,19 @@ static int acpi_battery_update(struct acpi_battery *battery)
 
 static void acpi_battery_refresh(struct acpi_battery *battery)
 {
+       int power_unit;
+
        if (!battery->bat.dev)
                return;
 
+       power_unit = battery->power_unit;
+
        acpi_battery_get_info(battery);
-       /* The battery may have changed its reporting units. */
+
+       if (power_unit == battery->power_unit)
+               return;
+
+       /* The battery has changed its reporting units. */
        sysfs_remove_battery(battery);
        sysfs_add_battery(battery);
 }