power: supply: max17042_battery: use VFSOC for capacity when no rsns

commit 223a3b8283 upstream.

On Galaxy S3 (i9300/i9305), which has the max17047 fuel gauge and no
current sense resistor (rsns), the RepSOC register does not provide an
accurate state of charge value. The reported value is wrong, and does
not change over time. VFSOC however, which uses the voltage fuel gauge
to determine the state of charge, always shows an accurate value.

For devices without current sense, VFSOC is already used for the
soc-alert (0x0003 is written to MiscCFG register), so with this change
the source of the alert and the PROP_CAPACITY value match.

Fixes: 359ab9f5b1 ("power_supply: Add MAX17042 Fuel Gauge Driver")
Cc: <stable@vger.kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Suggested-by: Wolfgang Wiedmeyer <wolfgit@wiedmeyer.de>
Signed-off-by: Henrik Grimler <henrik@grimler.se>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/power/supply/max17042_battery.c

@@ -313,7 +313,10 @@ static int max17042_get_property(struct power_supply *psy,
 		val->intval = data * 625 / 8;
 		break;
 	case POWER_SUPPLY_PROP_CAPACITY:
-		ret = regmap_read(map, MAX17042_RepSOC, &data);
+		if (chip->pdata->enable_current_sense)
+			ret = regmap_read(map, MAX17042_RepSOC, &data);
+		else
+			ret = regmap_read(map, MAX17042_VFSOC, &data);
 		if (ret < 0)
 			return ret;