From f496c09c0785b60fa6b762ad720ba31f6a9de0ac Mon Sep 17 00:00:00 2001
From: Jason Gerecke <killertofu@gmail.com>
Date: Fri, 28 Apr 2017 09:25:31 -0700
Subject: [PATCH] HID: wacom: generic: Ignore HID_DG_BATTERYSTRENTH == 0
Git-commit: f496c09c0785b60fa6b762ad720ba31f6a9de0ac
Patch-mainline: v4.13-rc1
References: bsc#1051510

AES sensors use the value 0 to indicate "not available" rather than
"completely dead". Such values are often sent for dozens of reports
while the pen is being brought into proximity and can cause userspace
to get the wrong impression about the actual battery state.

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Ping Cheng <ping.cheng@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/hid/wacom_wac.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index fd989e09ae2d..70a9e47b215a 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -2036,6 +2036,8 @@ static void wacom_wac_pen_event(struct hid_device *hdev, struct hid_field *field
 			wacom_wac->hid_data.sense_state = value;
 		return;
 	case HID_DG_BATTERYSTRENGTH:
+		if (value == 0) /* "not available" */
+			break;
 		value = value * 100 / (field->logical_maximum - field->logical_minimum);
 		wacom_wac->hid_data.battery_capacity = value;
 		wacom_wac->hid_data.bat_connected = 1;
-- 
2.16.4