power: supply: max17042_battery: Prevent int underflow in set_soc_threshold

max17042_set_soc_threshold gets called with offset set to 1, which means
that minimum threshold value would underflow once SOC got down to 0,
causing invalid alerts from the gauge.

Fixes: e5f3872d2044 ("max17042: Add support for signalling change in SOC")
Cc: <stable@vger.kernel.org>
Signed-off-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@puri.sm>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

diff --git a/drivers/power/supply/max17042_battery.c b/drivers/power/supply/max17042_battery.c
index 2eb61856f3e44ec28adbf1377b6916a89883a054..87128cf0d577566b3895cca853dfab4cc1d91036 100644 (file)
--- a/drivers/power/supply/max17042_battery.c
+++ b/drivers/power/supply/max17042_battery.c
@@ -860,7 +860,8 @@ static void max17042_set_soc_threshold(struct max17042_chip *chip, u16 off)
        regmap_read(map, MAX17042_RepSOC, &soc);
        soc >>= 8;
        soc_tr = (soc + off) << 8;
-       soc_tr |= (soc - off);
+       if (off < soc)
+               soc_tr |= soc - off;
        regmap_write(map, MAX17042_SALRT_Th, soc_tr);
 }