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.torok...@gmail.com>
---
 drivers/hid/hid-input.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 27d8442b017d..199f6a01fc62 100644
--- 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,
-- 
2.14.0.434.g98096fd7a8-goog


-- 
Dmitry

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