jz4740-battery: Correct voltage change check

The check is supposed to avoid redundant update notifications, so it
should check for the difference between old and new voltage exceeding
a threshold.

Also make sure the result of a failed read is never stored.

Signed-off-by: Maarten ter Huurne <maarten@treewalker.org>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

diff --git a/drivers/power/jz4740-battery.c b/drivers/power/jz4740-battery.c
index abdfc21ec13fc17bf99a2ca15e6ad2fc20ea6f0c..88f04f4d1a70d8d1311a440f16bfe4f52346df77 100644 (file)
--- a/drivers/power/jz4740-battery.c
+++ b/drivers/power/jz4740-battery.c
@@ -208,7 +208,7 @@ static void jz_battery_update(struct jz_battery *jz_battery)
        }
 
        voltage = jz_battery_read_voltage(jz_battery);
-       if (abs(voltage - jz_battery->voltage) < 50000) {
+       if (voltage >= 0 && abs(voltage - jz_battery->voltage) > 50000) {
                jz_battery->voltage = voltage;
                has_changed = true;
        }