[PATCH 13/17] HID: logitech-hidpp: make .probe usbhid capable

[Benjamin Tissoires]

The current custom solution for the G920 is not the best because
hid_hw_start() is not called at the end of the .probe().
It means that any configuration retrieved after the initial hid_hw_start
would not be exposed to user space without races.

We can simply force hid_hw_start to just enable the transport layer by
not using a connect_mask. This way, we can have a common path between
USB, Unifying and Bluetooth devices.

Tested with a G502 (plain USB), a T650 and many other unifying devices,
and the T651 over Bluetooth.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
---
 drivers/hid/hid-logitech-hidpp.c | 88 ++++++++++++++++++++++------------------
 1 file changed, 48 insertions(+), 40 deletions(-)

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index a5d37a4..f5889ff 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -2813,6 +2813,17 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	if (!hidpp_validate_device(hdev))
 		return hid_hw_start(hdev, HID_CONNECT_DEFAULT);
 
+	/*
+	 * HID++ needs to read incoming report while in .probe().
+	 * However, this doesn't work for plain USB devices until the hdev
+	 * status is set with HID_STAT_ADDED (device fully registered once
+	 * with HID).
+	 * So we ask for it to be reprobed later.
+	 */
+	if (id->group != HID_GROUP_LOGITECH_DJ_DEVICE &&
+	    !(hdev->status & HID_STAT_ADDED))
+		return -EPROBE_DEFER;
+
 	hidpp = devm_kzalloc(&hdev->dev, sizeof(struct hidpp_device),
 			GFP_KERNEL);
 	if (!hidpp)
@@ -2853,24 +2864,23 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 		hid_warn(hdev, "Cannot allocate sysfs group for %s\n",
 			 hdev->name);
 
-	if (hidpp->quirks & HIDPP_QUIRK_NO_HIDINPUT)
-		connect_mask &= ~HID_CONNECT_HIDINPUT;
-
-	if (hidpp->quirks & HIDPP_QUIRK_CLASS_G920) {
-		ret = hid_hw_start(hdev, connect_mask);
-		if (ret) {
-			hid_err(hdev, "hw start failed\n");
-			goto hid_hw_start_fail;
-		}
-		ret = hid_hw_open(hdev);
-		if (ret < 0) {
-			dev_err(&hdev->dev, "%s:hid_hw_open returned error:%d\n",
-				__func__, ret);
-			hid_hw_stop(hdev);
-			goto hid_hw_start_fail;
-		}
+	/*
+	 * Plain USB connections need to actually call start and open
+	 * on the transport driver to allow incoming data.
+	 */
+	ret = hid_hw_start(hdev, 0);
+	if (ret) {
+		hid_err(hdev, "hw start failed\n");
+		goto hid_hw_start_fail;
 	}
 
+	ret = hid_hw_open(hdev);
+	if (ret < 0) {
+		dev_err(&hdev->dev, "%s:hid_hw_open returned error:%d\n",
+			__func__, ret);
+		hid_hw_stop(hdev);
+		goto hid_hw_open_fail;
+	}
 
 	/* Allow incoming packets */
 	hid_device_io_start(hdev);
@@ -2880,7 +2890,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 		if (!connected) {
 			ret = -ENODEV;
 			hid_err(hdev, "Device not connected");
-			goto hid_hw_open_failed;
+			goto hid_hw_init_fail;
 		}
 
 		hid_info(hdev, "HID++ %u.%u device connected.\n",
@@ -2893,37 +2903,36 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	if (connected && (hidpp->quirks & HIDPP_QUIRK_CLASS_WTP)) {
 		ret = wtp_get_config(hidpp);
 		if (ret)
-			goto hid_hw_open_failed;
+			goto hid_hw_init_fail;
 	} else if (connected && (hidpp->quirks & HIDPP_QUIRK_CLASS_G920)) {
 		ret = g920_get_config(hidpp);
 		if (ret)
-			goto hid_hw_open_failed;
+			goto hid_hw_init_fail;
 	}
 
-	/* Block incoming packets */
-	hid_device_io_stop(hdev);
+	hidpp_connect_event(hidpp);
 
-	if (!(hidpp->quirks & HIDPP_QUIRK_CLASS_G920)) {
-		ret = hid_hw_start(hdev, connect_mask);
-		if (ret) {
-			hid_err(hdev, "%s:hid_hw_start returned error\n", __func__);
-			goto hid_hw_start_fail;
-		}
-	}
+	/* Reset the HID node state */
+	hid_device_io_stop(hdev);
+	hid_hw_close(hdev);
+	hid_hw_stop(hdev);
 
-	/* Allow incoming packets */
-	hid_device_io_start(hdev);
+	if (hidpp->quirks & HIDPP_QUIRK_NO_HIDINPUT)
+		connect_mask &= ~HID_CONNECT_HIDINPUT;
 
-	hidpp_connect_event(hidpp);
+	/* Now export the actual inputs and hidraw nodes to the world */
+	ret = hid_hw_start(hdev, connect_mask);
+	if (ret) {
+		hid_err(hdev, "%s:hid_hw_start returned error\n", __func__);
+		goto hid_hw_start_fail;
+	}
 
 	return ret;
 
-hid_hw_open_failed:
-	hid_device_io_stop(hdev);
-	if (hidpp->quirks & HIDPP_QUIRK_CLASS_G920) {
-		hid_hw_close(hdev);
-		hid_hw_stop(hdev);
-	}
+hid_hw_init_fail:
+	hid_hw_close(hdev);
+hid_hw_open_fail:
+	hid_hw_stop(hdev);
 hid_hw_start_fail:
 	sysfs_remove_group(&hdev->dev.kobj, &ps_attribute_group);
 	cancel_work_sync(&hidpp->work);
@@ -2942,10 +2951,9 @@ static void hidpp_remove(struct hid_device *hdev)
 
 	sysfs_remove_group(&hdev->dev.kobj, &ps_attribute_group);
 
-	if (hidpp->quirks & HIDPP_QUIRK_CLASS_G920) {
+	if (hidpp->quirks & HIDPP_QUIRK_CLASS_G920)
 		hidpp_ff_deinit(hdev);
-		hid_hw_close(hdev);
-	}
+
 	hid_hw_stop(hdev);
 	cancel_work_sync(&hidpp->work);
 	mutex_destroy(&hidpp->send_mutex);
-- 
2.9.3