HID: input: throttle battery uevents

The power_supply subsystem tends to emit uevent every time
power_supply_changed() is called, so we should call this API only when battery
strength reported by the device is actually different from the previous
readings, otherwise we'll drown the system in uevents.

Fixes: 581c4484769e ("HID: input: map digitizer battery usage")
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 27d8442b017dc0ada05355d5cd577948732be053..199f6a01fc629ead34108da7ddc895269ed0820a 100644 (file)
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -520,15 +520,21 @@ static void hidinput_cleanup_battery(struct hid_device *dev)
 
 static void hidinput_update_battery(struct hid_device *dev, int value)
 {
+       int capacity;
+
        if (!dev->battery)
                return;
 
        if (value == 0 || value < dev->battery_min || value > dev->battery_max)
                return;
 
-       dev->battery_capacity = hidinput_scale_battery_capacity(dev, value);
-       dev->battery_reported = true;
-       power_supply_changed(dev->battery);
+       capacity = hidinput_scale_battery_capacity(dev, value);
+
+       if (!dev->battery_reported || capacity != dev->battery_capacity) {
+               dev->battery_capacity = capacity;
+               dev->battery_reported = true;
+               power_supply_changed(dev->battery);
+       }
 }
 #else  /* !CONFIG_HID_BATTERY_STRENGTH */
 static int hidinput_setup_battery(struct hid_device *dev, unsigned report_type,