[PATCH] platform/x86: wmi: Lower verbosity of some duplicate GUID messages

[Mario Limonciello]

The WMI subsystem in the kernel currently tracks WMI devices by
a GUID string not by ACPI device.  The GUID used by the `wmi-bmof`
module however is available from many devices on nearly every machine.

This originally was though to be a bug, but as it happens on most
machines it is a design mistake.  As there isn't an active need to
get the binary from each of the `wmi-bmof` device, special case it
and lower the message to debugging.  This will help to identify if
there are other duplicate GUIDs in the wild.

If there are and the information contained in them is desirable it
may be worth considering a design change to the WMI subsystem to
access those.

Link: https://lkml.org/lkml/2017/12/8/913
Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
---
 drivers/platform/x86/wmi-bmof.c |  2 --
 drivers/platform/x86/wmi.c      | 10 ++++++++--
 include/linux/wmi.h             |  2 ++
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/platform/x86/wmi-bmof.c b/drivers/platform/x86/wmi-bmof.c
index 80137afb9753..af46e9e03376 100644
--- a/drivers/platform/x86/wmi-bmof.c
+++ b/drivers/platform/x86/wmi-bmof.c
@@ -18,8 +18,6 @@
 #include <linux/types.h>
 #include <linux/wmi.h>
 
-#define WMI_BMOF_GUID "05901221-D566-11D1-B2F0-00A0C9062910"
-
 struct bmof_priv {
 	union acpi_object *bmofdata;
 	struct bin_attribute bmof_bin_attr;
diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index aed293b5af81..d7a1f4bf443b 100644
--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -1157,6 +1157,9 @@ static void wmi_free_devices(struct acpi_device *device)
 static bool guid_already_parsed(struct acpi_device *device, const guid_t *guid)
 {
 	struct wmi_block *wblock;
+	guid_t guid_wmi_bmof;
+
+	guid_parse(WMI_BMOF_GUID, &guid_wmi_bmof);
 
 	list_for_each_entry(wblock, &wmi_block_list, list) {
 		if (guid_equal(&wblock->gblock.guid, guid)) {
@@ -1166,8 +1169,11 @@ static bool guid_already_parsed(struct acpi_device *device, const guid_t *guid)
 			 * we need to suppress GUIDs that are unique on a
 			 * given node but duplicated across nodes.
 			 */
-			dev_warn(&device->dev, "duplicate WMI GUID %pUL (first instance was on %s)\n",
-				 guid, dev_name(&wblock->acpi_device->dev));
+			if (guid_equal(guid, &guid_wmi_bmof))
+				dev_dbg(&device->dev, "duplicate WMI-BMOF GUID found\n");
+			else
+				dev_warn(&device->dev, "duplicate WMI GUID %pUL (first instance was on %s)\n",
+					 guid, dev_name(&wblock->acpi_device->dev));
 			return true;
 		}
 	}
diff --git a/include/linux/wmi.h b/include/linux/wmi.h
index b88d7b58e61e..59acdceb4411 100644
--- a/include/linux/wmi.h
+++ b/include/linux/wmi.h
@@ -13,6 +13,8 @@
 #include <linux/mod_devicetable.h>
 #include <uapi/linux/wmi.h>
 
+#define WMI_BMOF_GUID "05901221-D566-11D1-B2F0-00A0C9062910"
+
 struct wmi_device {
 	struct device dev;
 
-- 
2.34.1