platform/x86: asus-wmi: Improve DSTS WMI method ID detection

The DSTS method detection mistakenly selects DCTS instead of DSTS if
nothing is returned when the method ID is not defined in WMNB. As a result,
the control of keyboard backlight is not functional for TUF Gaming series
laptops. Implement detection based on _UID of the WMI device instead.

There is evidence that DCTS is handled by ACPI WMI devices that have _UID
ASUSWMI, whereas none of the devices without ASUSWMI respond to DCTS and
DSTS is used instead [1].

DSDT examples:

FX505GM (_UID ATK):
Method (WMNB, 3, Serialized)
{ ...
    If ((Local0 == 0x53545344))
    {
        ...
        Return (Zero)
    }
    ...
    // No return
}

K54C (_UID ATK):
Method (WMNB, 3, Serialized)
{ ...
    If ((Local0 == 0x53545344))
    {
        ...
        Return (0x02)
    }
    ...
    Return (0xFFFFFFFE)
}

Link: https://lkml.org/lkml/2019/4/11/322
Signed-off-by: Yurii Pavlovskyi <yurii.pavlovskyi@gmail.com>
Suggested-by: Daniel Drake <drake@endlessm.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

diff --git a/drivers/hid/hid-asus.c b/drivers/hid/hid-asus.c
index 336aeae..1d01fe2 100644 (file)
--- a/drivers/hid/hid-asus.c
+++ b/drivers/hid/hid-asus.c
@@ -396,7 +396,7 @@ static bool asus_kbd_wmi_led_control_present(struct hid_device *hdev)
        if (!IS_ENABLED(CONFIG_ASUS_WMI))
                return false;
 
-       ret = asus_wmi_evaluate_method(ASUS_WMI_METHODID_DSTS2,
+       ret = asus_wmi_evaluate_method(ASUS_WMI_METHODID_DSTS,
                                       ASUS_WMI_DEVID_KBD_BACKLIGHT, 0, &value);
        hid_dbg(hdev, "WMI backlight check: rc %d value %x", ret, value);
        if (ret)

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index c67f11e..ef526dc 100644 (file)
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -83,6 +83,8 @@ MODULE_LICENSE("GPL");
 #define USB_INTEL_XUSB2PR              0xD0
 #define PCI_DEVICE_ID_INTEL_LYNXPOINT_LP_XHCI  0x9c31
 
+#define ASUS_ACPI_UID_ASUSWMI          "ASUSWMI"
+
 static const char * const ashs_ids[] = { "ATK4001", "ATK4002", NULL };
 
 static bool ashs_present(void)
@@ -1874,6 +1876,8 @@ static int asus_wmi_sysfs_init(struct platform_device *device)
  */
 static int asus_wmi_platform_init(struct asus_wmi *asus)
 {
+       struct device *dev = &asus->platform_device->dev;
+       char *wmi_uid;
        int rv;
 
        /* INIT enable hotkeys on some models */
@@ -1903,11 +1907,24 @@ static int asus_wmi_platform_init(struct asus_wmi *asus)
         * Note, on most Eeepc, there is no way to check if a method exist
         * or note, while on notebooks, they returns 0xFFFFFFFE on failure,
         * but once again, SPEC may probably be used for that kind of things.
+        *
+        * Additionally at least TUF Gaming series laptops return nothing for
+        * unknown methods, so the detection in this way is not possible.
+        *
+        * There is strong indication that only ACPI WMI devices that have _UID
+        * equal to "ASUSWMI" use DCTS whereas those with "ATK" use DSTS.
         */
-       if (!asus_wmi_evaluate_method(ASUS_WMI_METHODID_DSTS, 0, 0, NULL))
+       wmi_uid = wmi_get_acpi_device_uid(ASUS_WMI_MGMT_GUID);
+       if (!wmi_uid)
+               return -ENODEV;
+
+       if (!strcmp(wmi_uid, ASUS_ACPI_UID_ASUSWMI)) {
+               dev_info(dev, "Detected ASUSWMI, use DCTS\n");
+               asus->dsts_id = ASUS_WMI_METHODID_DCTS;
+       } else {
+               dev_info(dev, "Detected %s, not ASUSWMI, use DSTS\n", wmi_uid);
                asus->dsts_id = ASUS_WMI_METHODID_DSTS;
-       else
-               asus->dsts_id = ASUS_WMI_METHODID_DSTS2;
+       }
 
        /* CWAP allow to define the behavior of the Fn+F2 key,
         * this method doesn't seems to be present on Eee PCs */

diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
index bfba245..0668f76 100644 (file)
--- a/include/linux/platform_data/x86/asus-wmi.h
+++ b/include/linux/platform_data/x86/asus-wmi.h
@@ -18,8 +18,8 @@
 #define ASUS_WMI_METHODID_GDSP         0x50534447 /* Get DiSPlay output */
 #define ASUS_WMI_METHODID_DEVP         0x50564544 /* DEVice Policy */
 #define ASUS_WMI_METHODID_OSVR         0x5256534F /* OS VeRsion */
-#define ASUS_WMI_METHODID_DSTS         0x53544344 /* Device STatuS */
-#define ASUS_WMI_METHODID_DSTS2                0x53545344 /* Device STatuS #2*/
+#define ASUS_WMI_METHODID_DCTS         0x53544344 /* Device status (DCTS) */
+#define ASUS_WMI_METHODID_DSTS         0x53545344 /* Device status (DSTS) */
 #define ASUS_WMI_METHODID_BSTS         0x53545342 /* Bios STatuS ? */
 #define ASUS_WMI_METHODID_DEVS         0x53564544 /* DEVice Set */
 #define ASUS_WMI_METHODID_CFVS         0x53564643 /* CPU Frequency Volt Set */