diff --git a/Documentation/laptops/thinkpad-acpi.txt b/Documentation/laptops/thinkpad-acpi.txt
index e2ddcdeb61b6f5caffa1f80f901ebf5619f93dd7..ab4b58eaa7f4a5561502d092631bc6430a293469 100644
--- a/Documentation/laptops/thinkpad-acpi.txt
+++ b/Documentation/laptops/thinkpad-acpi.txt
@@ -240,9 +240,13 @@ sysfs notes:
 		Returns 0.
 
 	hotkey_bios_mask:
+		DEPRECATED, DON'T USE, WILL BE REMOVED IN THE FUTURE.
+
 		Returns the hot keys mask when thinkpad-acpi was loaded.
 		Upon module unload, the hot keys mask will be restored
-		to this value.
+		to this value.   This is always 0x80c, because those are
+		the hotkeys that were supported by ancient firmware
+		without mask support.
 
 	hotkey_enable:
 		DEPRECATED, WILL BE REMOVED SOON.
diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index 679a73b43191d02ce5c43f89e73656dde4fbebfe..6b667891fc3b09161950d6d723fe71ace56ddacb 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -2544,6 +2544,8 @@ static ssize_t hotkey_bios_mask_show(struct device *dev,
 			   struct device_attribute *attr,
 			   char *buf)
 {
+	printk_deprecated_attribute("hotkey_bios_mask",
+			"This attribute is useless.");
 	return snprintf(buf, PAGE_SIZE, "0x%08x\n", hotkey_orig_mask);
 }