power: supply: sbs-battery: only return health when battery present

when the battery is set to sbs-mode and  no gpio detection is enabled
"health" is always returning a value even when the battery is not present.
All other fields return "not present".
This leads to a scenario where the driver is constantly switching between
"present" and "not present" state. This generates a lot of constant
traffic on the i2c.

This commit changes the response of "health" to an error when the battery
is not responding leading to a consistent "not present" state.

Fixes: 76b16f4c ("power: supply: sbs-battery: don't assume MANUFACTURER_DATA formats")
Cc: <stable@vger.kernel.org>
Signed-off-by: Michael Nosthoff <committed@heine.so>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/sbs-battery.c

@@ -314,17 +314,22 @@ static int sbs_get_battery_presence_and_health(
 {
 	int ret;
 
-	if (psp == POWER_SUPPLY_PROP_PRESENT) {
 	/* Dummy command; if it succeeds, battery is present. */
 	ret = sbs_read_word_data(client, sbs_data[REG_STATUS].addr);
-		if (ret < 0)
-			val->intval = 0; /* battery disconnected */
-		else
+
+	if (ret < 0) { /* battery not present*/
+		if (psp == POWER_SUPPLY_PROP_PRESENT) {
+			val->intval = 0;
+			return 0;
+		}
+		return ret;
+	}
+
+	if (psp == POWER_SUPPLY_PROP_PRESENT)
 		val->intval = 1; /* battery present */
-	} else { /* POWER_SUPPLY_PROP_HEALTH */
+	else /* POWER_SUPPLY_PROP_HEALTH */
 		/* SBS spec doesn't have a general health command. */
 		val->intval = POWER_SUPPLY_HEALTH_UNKNOWN;
-	}
 
 	return 0;
 }
@@ -626,6 +631,8 @@ static int sbs_get_property(struct power_supply *psy,
 		else
 			ret = sbs_get_battery_presence_and_health(client, psp,
 								  val);
+
+		/* this can only be true if no gpio is used */
 		if (psp == POWER_SUPPLY_PROP_PRESENT)
 			return 0;
 		break;