ACPI battery: only refresh the sysfs files when pertinent information changes

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>

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index 86933ca8b4724372505530de753332907f488ebe..7dd3f9fb9f3f21b808e30b8aa78f65fce7b2275a 100644 (file)
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -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);
 }