[PATCH 5.10.y 3/4] power: supply: max17040: Check iio_read_channel_processed() return code

[Sasha Levin <sashal@kernel.org>]

From: Ivan Abramov <i.abramov@mt-integration.ru>

[ Upstream commit 2c68ac48c52ad146523f32b01d70009622bf81aa ]

Since iio_read_channel_processed() may fail, return its exit code on error.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 814755c48f8b ("power: max17040: get thermal data from adc if available")
Signed-off-by: Ivan Abramov <i.abramov@mt-integration.ru>
Link: https://patch.msgid.link/20251008133648.559286-1-i.abramov@mt-integration.ru
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

[Stable dependency adaptation]
The 5.10 driver has no IIO temperature channel or TEMP property, so omit
the temperature-read hunk and its unavailable supplier-status context.
Retain the local ret variable required by 659cc3d8d5ef ("power: supply:
max17040: propagate register read errors"), which uses it without adding
a declaration in max17040_get_property().

Initialize ret to -EINVAL and use it for the existing unsupported-property
return. This avoids an unused-variable warning before the target is
applied, while keeping successful callbacks returning zero even after
the target stores positive voltage or capacity values in ret. No driver
functions or new properties are added.

Stable-dep-of: 659cc3d8d5ef ("power: supply: max17040: propagate register read errors")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/power/supply/max17040_battery.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/power/supply/max17040_battery.c b/drivers/power/supply/max17040_battery.c
index 8b2f0726ef0c0..fad244a73c8ea 100644
--- a/drivers/power/supply/max17040_battery.c
+++ b/drivers/power/supply/max17040_battery.c
@@ -392,6 +392,7 @@ static int max17040_get_property(struct power_supply *psy,
 			    union power_supply_propval *val)
 {
 	struct max17040_chip *chip = power_supply_get_drvdata(psy);
+	int ret = -EINVAL;
 
 	switch (psp) {
 	case POWER_SUPPLY_PROP_ONLINE:
@@ -407,7 +408,7 @@ static int max17040_get_property(struct power_supply *psy,
 		val->intval = chip->low_soc_alert;
 		break;
 	default:
-		return -EINVAL;
+		return ret;
 	}
 	return 0;
 }
-- 
2.53.0