[PATCH v2 1/2] hwmon: (max6621) fix temperature clamp range

MAX6621_TEMP_INPUT_MIN and MAX6621_TEMP_INPUT_MAX are used to clamp the
writable offset and critical thresholds. They are defined as -127000 and
128000.

The driver decodes the temperature through an s8 and its own comment in
max6621_read() documents an 8-bit two's complement value, whose range is
-128 to +127 degrees C. The current limits therefore reject the valid
-128 degrees C and accept +128 degrees C, which does not fit the 8-bit
range.

Correct the limits to -128000 and 127000.

Fixes: 92b64580f14b ("hwmon: (max6621) Add support for Maxim MAX6621 temperature sensor")
Cc: [email protected]
Assisted-by: Claude:claude-opus-4
Signed-off-by: Cong Nguyen <[email protected]>
---
Changes in v2:
 - Drop the temperature input change; it was not a bug (temp_input already
   sign-extends correctly via an s8 intermediate).
 - Drop the incorrect changelog reasoning (no "+128 degC", no PECI/16-bit).
 - Split into two patches per review: this one fixes the clamp range; 2/2
   fixes the negative offset/crit reads.
 - No 1/64 degC precision change (not documented in the datasheet).

 drivers/hwmon/max6621.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/max6621.c b/drivers/hwmon/max6621.c
index a7066f3a0bb4..ee5898fbe110 100644
--- a/drivers/hwmon/max6621.c
+++ b/drivers/hwmon/max6621.c
@@ -17,8 +17,8 @@
 
 #define MAX6621_DRV_NAME		"max6621"
 #define MAX6621_TEMP_INPUT_REG_NUM	9
-#define MAX6621_TEMP_INPUT_MIN		-127000
-#define MAX6621_TEMP_INPUT_MAX		128000
+#define MAX6621_TEMP_INPUT_MIN		-128000
+#define MAX6621_TEMP_INPUT_MAX		127000
 #define MAX6621_TEMP_ALERT_CHAN_SHIFT	1
 
 #define MAX6621_TEMP_S0D0_REG		0x00
-- 
2.25.1