From:   Denis Pauk <pauk.denis@gmail.com>
Cc:     andy.shevchenko@gmail.com, pauk.denis@gmail.com,
        platform-driver-x86@vger.kernel.org,
        Guenter Roeck <linux@roeck-us.net>,
        Jean Delvare <jdelvare@suse.com>, linux-hwmon@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH 1/1] hwmon: (nct6775) Additional check for ChipID before ASUS WMI usage
Date:   Sat, 18 Dec 2021 21:26:16 +0200
Message-Id: <20211218192616.611878-1-pauk.denis@gmail.com>
MIME-Version: 1.0
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To:     unlisted-recipients:; (no To-header on input)
Precedence: bulk

WMI monitoring methods can be changed or removed in new ASUS boards
BIOS versions. Such versions return zero instead of a real one as
Chip ID.

Commit adds additional validation for the result of Chip ID call
before enabling access by ASUS WMI methods.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=204807
Signed-off-by: Denis Pauk <pauk.denis@gmail.com>
---
 drivers/hwmon/nct6775.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/nct6775.c b/drivers/hwmon/nct6775.c
index 57ce8633a725..034347ed51c4 100644
--- a/drivers/hwmon/nct6775.c
+++ b/drivers/hwmon/nct6775.c
@@ -5038,7 +5038,8 @@ static int __init sensors_nct6775_init(void)
 				   board_name);
 		if (err >= 0) {
 			/* if reading chip id via WMI succeeds, use WMI */
-			if (!nct6775_asuswmi_read(0, NCT6775_PORT_CHIPID, &tmp)) {
+			if (!nct6775_asuswmi_read(0, NCT6775_PORT_CHIPID, &tmp) &&
+			    tmp) {
 				pr_info("Using Asus WMI to access %#x chip.\n", tmp);
 				access = access_asuswmi;
 			} else {

base-commit: 2585cf9dfaaddf00b069673f27bb3f8530e2039c
-- 
2.34.1