[PATCH v2 2/4] iio: imu: inv_icm42600: warn on whoami mismatch instead of failing probe

[Jorijn van der Graaf]

A WHOAMI value differing from the one the compatible implies aborts
probe with -ENODEV, which prevents a register-compatible part described
with a fallback compatible from probing at all.

The devicetree compatible is authoritative for which part is fitted:
demote the mismatch to a warning and continue, as st_sensors does since
commit a3c2c5c937ed ("iio: st_sensors: relax WhoAmI check in
st_sensors_verify_id()"). This changes the probe outcome on mismatch
for all parts the driver supports.

Tested via a backport to a Fairphone 6 running a 7.1-based kernel: its
ICM-42630 (WHOAMI 0x0C), described with an icm42631 fallback compatible
and matched as icm42631, warns once and probes, and accelerometer,
gyroscope and temperature reads work.

Suggested-by: Conor Dooley <conor@xxxxxxxxxx>
Link: https://lore.kernel.org/all/20260722-creature-volley-0f083b904c1d@spud/
Assisted-by: Claude:claude-fable-5
Signed-off-by: Jorijn van der Graaf <jorijnvdgraaf@xxxxxxxxxxxxx>
---
New in v2.
 drivers/iio/imu/inv_icm42600/inv_icm42600_core.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_core.c b/drivers/iio/imu/inv_icm42600/inv_icm42600_core.c
index dc97d8a274e3..f306e3ffca48 100644
--- a/drivers/iio/imu/inv_icm42600/inv_icm42600_core.c
+++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_core.c
@@ -509,11 +509,9 @@ static int inv_icm42600_setup(struct inv_icm42600_state *st,
 	ret = regmap_read(st->map, INV_ICM42600_REG_WHOAMI, &val);
 	if (ret)
 		return ret;
-	if (val != hw->whoami) {
-		dev_err(dev, "invalid whoami %#02x expected %#02x (%s)\n",
-			val, hw->whoami, hw->name);
-		return -ENODEV;
-	}
+	if (val != hw->whoami)
+		dev_warn(dev, "unexpected whoami %#02x, expected %#02x (%s)\n",
+			 val, hw->whoami, hw->name);
 	st->name = hw->name;
 
 	/* reset to make sure previous state are not there */
-- 
2.55.0