linux-kernel - [PATCH] platform/x86: dell-wmi-sysman: work around for BIOS bug

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Date:   Wed,  2 Dec 2020 12:26:36 +0530
From:   Divya Bharathi <divya27392@...il.com>
To:     dvhart@...radead.org, Hans de Goede <hdegoede@...hat.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        platform-driver-x86@...r.kernel.org,
        Divya Bharathi <divya.bharathi@...l.com>,
        Mario Limonciello <mario.limonciello@...l.com>,
        Prasanth KSR <prasanth.ksr@...l.com>
Subject: [PATCH] platform/x86: dell-wmi-sysman: work around for BIOS bug

BIOS sets incorrect value (zero) when SET value passed for integer attribute
with + sign. Added workaround to remove + sign before passing input to BIOS

Co-developed-by: Mario Limonciello <mario.limonciello@...l.com>
Signed-off-by: Mario Limonciello <mario.limonciello@...l.com>
Co-developed-by: Prasanth KSR <prasanth.ksr@...l.com>
Signed-off-by: Prasanth KSR <prasanth.ksr@...l.com>
Signed-off-by: Divya Bharathi <divya.bharathi@...l.com>
---
 drivers/platform/x86/dell-wmi-sysman/int-attributes.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/dell-wmi-sysman/int-attributes.c b/drivers/platform/x86/dell-wmi-sysman/int-attributes.c
index ea773d8e8d3a..f30d155135c3 100644
--- a/drivers/platform/x86/dell-wmi-sysman/int-attributes.c
+++ b/drivers/platform/x86/dell-wmi-sysman/int-attributes.c
@@ -39,7 +39,7 @@ static ssize_t current_value_show(struct kobject *kobj, struct kobj_attribute *a
  * @instance_id: The instance on which input is validated
  * @buf: Input value
  */
-static int validate_integer_input(int instance_id, const char *buf)
+static int validate_integer_input(int instance_id, char *buf)
 {
 	int in_val;
 	int ret;
@@ -51,6 +51,12 @@ static int validate_integer_input(int instance_id, const char *buf)
 			in_val > wmi_priv.integer_data[instance_id].max_value)
 		return -EINVAL;
 
+	/* workaround for BIOS error.
+	 * validate input to avoid setting 0 when integer input passed with + sign
+	 */
+	if (*buf == '+')
+		memmove(buf, (buf + 1), strlen(buf));
+
 	return ret;
 }
 
-- 
2.25.1