[PATCH 6.6.y 1/2] 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]
Linux 6.6 does not contain the optional IIO temperature support introduced
by 814755c48f8b, so omit the temperature-read error-checking hunk and the
unavailable status/temperature context.

Retain the local ret declaration: target 659cc3d8d5ef uses it to propagate
voltage and capacity read errors without adding a declaration of its own.
Use ret for the existing -EINVAL default case so this dependency builds
without an unused-variable warning before the target is applied. Keep the
successful return as zero; the target stores positive readings in ret.

This is a prerequisite-only adaptation with unchanged driver behavior and
no added functions.

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 | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/power/supply/max17040_battery.c b/drivers/power/supply/max17040_battery.c
index ff42db6728991..28c66c1fe6e43 100644
--- a/drivers/power/supply/max17040_battery.c
+++ b/drivers/power/supply/max17040_battery.c
@@ -386,6 +386,7 @@ 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;
 
 	switch (psp) {
 	case POWER_SUPPLY_PROP_ONLINE:
@@ -401,7 +402,8 @@ static int max17040_get_property(struct power_supply *psy,
 		val->intval = chip->low_soc_alert;
 		break;
 	default:
-		return -EINVAL;
+		ret = -EINVAL;
+		return ret;
 	}
 	return 0;
 }
-- 
2.53.0