[PATCH 1/3] hwmon: lenovo-ec-sensors: Fix EC signature check logic in probe

[Kean <rh_king@163.com>]

The probe function reads a 4-byte signature ("MCHP") from the EC to
verify it is a Microchip EC before binding the driver. The condition
uses && (AND) to check if each byte differs from the expected value:

  if ((byte0 != 'M') && (byte1 != 'C') && (byte2 != 'H') && (byte3 != 'P'))

This rejects the device only if ALL four bytes are wrong simultaneously.
A partially matching signature (e.g. "MXXX") would pass the check and
cause the driver to bind to a non-Microchip EC, as long as at least one
byte matches the expected value.

Change && to || so the driver is rejected when ANY byte does not match
the expected "MCHP" signature.

Signed-off-by: Kean <rh_king@163.com>

Reviewed-by: Mark Pearson <mpearson-lenovo@squebb.ca>
---
 drivers/hwmon/lenovo-ec-sensors.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/lenovo-ec-sensors.c b/drivers/hwmon/lenovo-ec-sensors.c
index 8681bbf6665b..a32b1f2c6a3a 100644
--- a/drivers/hwmon/lenovo-ec-sensors.c
+++ b/drivers/hwmon/lenovo-ec-sensors.c
@@ -537,9 +537,9 @@ static int lenovo_ec_probe(struct platform_device *pdev)
 	outw_p(MCHP_SING_IDX, MCHP_EMI0_EC_ADDRESS);
 	mutex_unlock(&ec_data->mec_mutex);
 
-	if ((inb_p(MCHP_EMI0_EC_DATA_BYTE0) != 'M') &&
-	    (inb_p(MCHP_EMI0_EC_DATA_BYTE1) != 'C') &&
-	    (inb_p(MCHP_EMI0_EC_DATA_BYTE2) != 'H') &&
+	if ((inb_p(MCHP_EMI0_EC_DATA_BYTE0) != 'M') || 
+	    (inb_p(MCHP_EMI0_EC_DATA_BYTE1) != 'C') || 
+	    (inb_p(MCHP_EMI0_EC_DATA_BYTE2) != 'H') ||
 	    (inb_p(MCHP_EMI0_EC_DATA_BYTE3) != 'P')) {
 		release_region(IO_REGION_START, IO_REGION_LENGTH);
 		return -ENODEV;
-- 
2.47.3