[PATCH 02/11] HID: asus: prevent binding to all HID devices on ROG

[Antheas Kapenekakis <lkml@antheas.dev>]

ROG keyboards are HID compliant. We only care about the endpoint that
produces vendor events (e.g., fan mode) and has the keyboard backlight.
If we attach to all the endpoints, we end up generating errors during
probe for two of them because they are missing the ->input attribute
and risk side effects during input fixups.

Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
---
 drivers/hid/hid-asus.c | 54 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 53 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/hid-asus.c b/drivers/hid/hid-asus.c
index 8d4df1b6f143b..5eb70716702ef 100644
--- a/drivers/hid/hid-asus.c
+++ b/drivers/hid/hid-asus.c
@@ -84,6 +84,7 @@ MODULE_DESCRIPTION("Asus HID Keyboard and TouchPad");
 #define QUIRK_MEDION_E1239T		BIT(10)
 #define QUIRK_ROG_NKEY_KEYBOARD		BIT(11)
 #define QUIRK_ROG_CLAYMORE_II_KEYBOARD BIT(12)
+#define QUIRK_HANDLE_GENERIC		BIT(13)
 
 #define I2C_KEYBOARD_QUIRKS			(QUIRK_FIX_NOTEBOOK_REPORT | \
 						 QUIRK_NO_INIT_REPORTS | \
@@ -326,6 +327,10 @@ static int asus_raw_event(struct hid_device *hdev,
 {
 	struct asus_drvdata *drvdata = hid_get_drvdata(hdev);
 
+	if (drvdata->quirks & QUIRK_HANDLE_GENERIC)
+		/* NOOP on generic HID devices to avoid side effects. */
+		return 0;
+
 	if (drvdata->battery && data[0] == BATTERY_REPORT_ID)
 		return asus_report_battery(drvdata, data, size);
 
@@ -774,6 +779,10 @@ static int asus_input_configured(struct hid_device *hdev, struct hid_input *hi)
 	struct input_dev *input = hi->input;
 	struct asus_drvdata *drvdata = hid_get_drvdata(hdev);
 
+	if (drvdata->quirks & QUIRK_HANDLE_GENERIC)
+		/* NOOP on generic HID devices to avoid side effects. */
+		return 0;
+
 	/* T100CHI uses MULTI_INPUT, bind the touchpad to the mouse hid_input */
 	if (drvdata->quirks & QUIRK_T100CHI &&
 	    hi->report->id != T100CHI_MOUSE_REPORT_ID)
@@ -851,6 +860,10 @@ static int asus_input_mapping(struct hid_device *hdev,
 		return -1;
 	}
 
+	if (drvdata->quirks & QUIRK_HANDLE_GENERIC)
+		/* NOOP on generic HID devices to avoid side effects. */
+		return 0;
+
 	/*
 	 * Ignore a bunch of bogus collections in the T100CHI descriptor.
 	 * This avoids a bunch of non-functional hid_input devices getting
@@ -1026,8 +1039,10 @@ static int __maybe_unused asus_reset_resume(struct hid_device *hdev)
 
 static int asus_probe(struct hid_device *hdev, const struct hid_device_id *id)
 {
-	int ret;
+	struct hid_report_enum *rep_enum;
 	struct asus_drvdata *drvdata;
+	struct hid_report *rep;
+	int ret, found = 0;
 
 	drvdata = devm_kzalloc(&hdev->dev, sizeof(*drvdata), GFP_KERNEL);
 	if (drvdata == NULL) {
@@ -1111,6 +1126,39 @@ static int asus_probe(struct hid_device *hdev, const struct hid_device_id *id)
 		return ret;
 	}
 
+	if (drvdata->quirks & QUIRK_ROG_NKEY_KEYBOARD) {
+		/*
+		 * The only application we care about on ROG NKEY keyboards is
+		 * 0xff310076. This is meant Asus drivers and uses report 0x54.
+		 */
+		rep_enum = &hdev->report_enum[HID_INPUT_REPORT];
+		list_for_each_entry(rep, &rep_enum->report_list, list) {
+			if (rep->application == 0xff310076)
+				found = true;
+		}
+
+		/*
+		 * If we didn't find the application, block hid-asus fixups
+		 * to prevent side effects on generic endpoints.
+		 *
+		 * We cannot -ENODEV here, as hid-generic checked our id_table
+		 * on its match and bailed so it will not take over the device.
+		 * We have to handle it transparently as part of this driver.
+		 */
+		if (!found) {
+			drvdata->quirks |= QUIRK_HANDLE_GENERIC;
+			hdev->quirks |= HID_QUIRK_INPUT_PER_APP;
+		}
+
+		/*
+		 * Start all endpoints normally. Include the RGB endpoint
+		 * as it being the only one renamed looks out of place.
+		 * The ->input bail causes regressions in endpoints without
+		 * an input dev and is a NOOP on the RGB endpoint.
+		 */
+		return hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	}
+
 	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
 	if (ret) {
 		hid_err(hdev, "Asus hw start failed: %d\n", ret);
@@ -1167,6 +1215,10 @@ static const __u8 *asus_report_fixup(struct hid_device *hdev, __u8 *rdesc,
 {
 	struct asus_drvdata *drvdata = hid_get_drvdata(hdev);
 
+	if (drvdata->quirks & QUIRK_HANDLE_GENERIC)
+		/* NOOP on generic HID devices to avoid side effects. */
+		return rdesc;
+
 	if (drvdata->quirks & QUIRK_FIX_NOTEBOOK_REPORT &&
 			*rsize >= 56 && rdesc[54] == 0x25 && rdesc[55] == 0x65) {
 		hid_info(hdev, "Fixing up Asus notebook report descriptor\n");
-- 
2.48.1