platform/x86: asus-wmi: Consider device is absent when the read is ~0

AAEON PICO-TGU4 board doesn't have any LED but there are bogus LED
controls under /sys/class/leds:
$ ls /sys/class/leds
asus::kbd_backlight asus::lightbar  platform::micmute

The reason is that the ~0 read from asus_wmi_get_devstate() is treated
as a valid state, in truth it means the device is absent.

So filter out ~0 read to prevent bogus LED controls being created.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20240308053255.224496-1-kai.heng.feng@canonical.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index 2865af89e95c233b4b35df0ad260bc409ac3c9a2..3f07bbf809ef01990c7e3bc64f02dc4eddfaf435 100644 (file)
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -481,7 +481,17 @@ static int asus_wmi_evaluate_method_agfn(const struct acpi_buffer args)
 
 static int asus_wmi_get_devstate(struct asus_wmi *asus, u32 dev_id, u32 *retval)
 {
-       return asus_wmi_evaluate_method(asus->dsts_id, dev_id, 0, retval);
+       int err;
+
+       err = asus_wmi_evaluate_method(asus->dsts_id, dev_id, 0, retval);
+
+       if (err)
+               return err;
+
+       if (*retval == ~0)
+               return -ENODEV;
+
+       return 0;
 }
 
 static int asus_wmi_set_devstate(u32 dev_id, u32 ctrl_param,