[PATCH v6 1/7] HID: asus: refactor init sequence per spec

Antheas Kapenekakis
2025-10-13T20:17:49Z

Currently, asus_kbd_init() uses a reverse engineered init sequence
from Windows, which contains the handshakes from multiple programs.
Keep the main one, which is 0x5a (meant for brightness drivers).

In addition, perform a get_response and check if the response is the
same. To avoid regressions, print an error if the response does not
match instead of rejecting device.

Then, refactor asus_kbd_get_functions() to use the same ID it is called
with, instead of hardcoding it to 0x5a so that it may be used for 0x0d
in the future.

Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
---
drivers/hid/hid-asus.c | 91 ++++++++++++++++++++++--------------------
1 file changed, 48 insertions(+), 43 deletions(-)

diff --git a/drivers/hid/hid-asus.c b/drivers/hid/hid-asus.c
index a444d41e53b6..d0c783df99bc 100644
--- a/drivers/hid/hid-asus.c
+++ b/drivers/hid/hid-asus.c
@@ -48,7 +48,7 @@ MODULE_DESCRIPTION("Asus HID Keyboard and TouchPad");
#define FEATURE_REPORT_ID 0x0d
#define INPUT_REPORT_ID 0x5d
#define FEATURE_KBD_REPORT_ID 0x5a
-#define FEATURE_KBD_REPORT_SIZE 16
+#define FEATURE_KBD_REPORT_SIZE 64
#define FEATURE_KBD_LED_REPORT_ID1 0x5d
#define FEATURE_KBD_LED_REPORT_ID2 0x5e

@@ -393,14 +393,37 @@ static int asus_kbd_set_report(struct hid_device *hdev, const u8 *buf, size_t bu

static int asus_kbd_init(struct hid_device *hdev, u8 report_id)
{
- const u8 buf[] = { report_id, 0x41, 0x53, 0x55, 0x53, 0x20, 0x54,
- 0x65, 0x63, 0x68, 0x2e, 0x49, 0x6e, 0x63, 0x2e, 0x00 };
+ /*
+ * The handshake is first sent as a set_report, then retrieved
+ * from a get_report. They should be equal.
+ */
+ const u8 buf[] = { report_id, 0x41, 0x53, 0x55, 0x53, 0x20,
+ 0x54, 0x65, 0x63, 0x68, 0x2e, 0x49, 0x6e, 0x63, 0x2e, 0x00 };
+ u8 *readbuf;
int ret;

ret = asus_kbd_set_report(hdev, buf, sizeof(buf));
- if (ret < 0)
- hid_err(hdev, "Asus failed to send init command: %d\n", ret);
+ if (ret < 0) {
+ hid_err(hdev, "Asus failed to send handshake: %d\n", ret);
+ return ret;
+ }
+
+ readbuf = kzalloc(FEATURE_KBD_REPORT_SIZE, GFP_KERNEL);
+ if (!readbuf)
+ return -ENOMEM;
+
+ ret = hid_hw_raw_request(hdev, report_id, readbuf,
+ FEATURE_KBD_REPORT_SIZE, HID_FEATURE_REPORT,
+ HID_REQ_GET_REPORT);
+ if (ret < 0) {
+ hid_err(hdev, "Asus failed to receive handshake ack: %d\n", ret);
+ } else if (memcmp(readbuf, buf, sizeof(buf)) != 0) {
+ hid_warn(hdev, "Asus handshake returned invalid response: %*ph\n",
+ FEATURE_KBD_REPORT_SIZE, readbuf);
+ // Do not return error if handshake is wrong to avoid regressions
+ }

+ kfree(readbuf);
return ret;
}

@@ -422,7 +445,7 @@ static int asus_kbd_get_functions(struct hid_device *hdev,
if (!readbuf)
return -ENOMEM;

- ret = hid_hw_raw_request(hdev, FEATURE_KBD_REPORT_ID, readbuf,
+ ret = hid_hw_raw_request(hdev, report_id, readbuf,
FEATURE_KBD_REPORT_SIZE, HID_FEATURE_REPORT,
HID_REQ_GET_REPORT);
if (ret < 0) {
@@ -638,50 +661,32 @@ static int asus_kbd_register_leds(struct hid_device *hdev)
unsigned char kbd_func;
int ret;

- if (drvdata->quirks & QUIRK_ROG_NKEY_KEYBOARD) {
- /* Initialize keyboard */
- ret = asus_kbd_init(hdev, FEATURE_KBD_REPORT_ID);
- if (ret < 0)
- return ret;
-
- /* The LED endpoint is initialised in two HID */
- ret = asus_kbd_init(hdev, FEATURE_KBD_LED_REPORT_ID1);
- if (ret < 0)
- return ret;
-
- ret = asus_kbd_init(hdev, FEATURE_KBD_LED_REPORT_ID2);
- if (ret < 0)
- return ret;
-
- if (dmi_match(DMI_PRODUCT_FAMILY, "ProArt P16")) {
- ret = asus_kbd_disable_oobe(hdev);
- if (ret < 0)
- return ret;
- }
-
- if (drvdata->quirks & QUIRK_ROG_ALLY_XPAD) {
- intf = to_usb_interface(hdev->dev.parent);
- udev = interface_to_usbdev(intf);
- validate_mcu_fw_version(hdev,
- le16_to_cpu(udev->descriptor.idProduct));
- }
+ ret = asus_kbd_init(hdev, FEATURE_KBD_REPORT_ID);
+ if (ret < 0)
+ return ret;

- } else {
- /* Initialize keyboard */
- ret = asus_kbd_init(hdev, FEATURE_KBD_REPORT_ID);
- if (ret < 0)
- return ret;
+ /* Get keyboard functions */
+ ret = asus_kbd_get_functions(hdev, &kbd_func, FEATURE_KBD_REPORT_ID);
+ if (ret < 0)
+ return ret;

- /* Get keyboard functions */
- ret = asus_kbd_get_functions(hdev, &kbd_func, FEATURE_KBD_REPORT_ID);
+ if (dmi_match(DMI_PRODUCT_FAMILY, "ProArt P16")) {
+ ret = asus_kbd_disable_oobe(hdev);
if (ret < 0)
return ret;
+ }

- /* Check for backlight support */
- if (!(kbd_func & SUPPORT_KBD_BACKLIGHT))
- return -ENODEV;
+ if (drvdata->quirks & QUIRK_ROG_ALLY_XPAD) {
+ intf = to_usb_interface(hdev->dev.parent);
+ udev = interface_to_usbdev(intf);
+ validate_mcu_fw_version(
+ hdev, le16_to_cpu(udev->descriptor.idProduct));
}

+ /* Check for backlight support */
+ if (!(kbd_func & SUPPORT_KBD_BACKLIGHT))
+ return -ENODEV;
+
drvdata->kbd_backlight = devm_kzalloc(&hdev->dev,
sizeof(struct asus_kbd_leds),
GFP_KERNEL);
--
2.51.0