[PATCH v2 2/2] Bluetooth: btusb: restore powered-off Intel adapters

[Sean Rhodes]

ACPI-managed internal USB ports can lose power while the Bluetooth
adapter is closed. The USB core then reset-resumes the device and, because
btusb has no reset-resume callback, rebinds its interfaces.

For a closed, fixed Intel combined adapter on an ACPI-power-manageable
port, preserve the binding and run the Intel setup again when the adapter
is next opened. Keep the existing rebind behavior while HCI is running and
keep runtime autosuspend blocked for other reset-resume-quirked adapters.

Tested on a Star Labs Lite Mk IV with Intel 8087:0aaa. Three Bluetooth
off/on cycles reached ACPI D3cold, restored the same hci0 without a USB
disconnect, and discovery found nearby devices after resume.

Signed-off-by: Sean Rhodes <sean@starlabs.systems>
---
 drivers/bluetooth/btusb_main.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/bluetooth/btusb_main.c b/drivers/bluetooth/btusb_main.c
index be47ac894b6c..4b6ac67f182f 100644
--- a/drivers/bluetooth/btusb_main.c
+++ b/drivers/bluetooth/btusb_main.c
@@ -2190,6 +2190,16 @@ static void btusb_prepare_reset(struct hci_dev *hdev)
 	usb_kill_anchored_urbs(&data->tx_anchor);
 }
 
+static bool btusb_intel_acpi_power_manageable(struct btusb_data *data)
+{
+	return IS_ENABLED(CONFIG_ACPI) &&
+	       data->match_id->driver_info & BTUSB_INTEL_COMBINED &&
+	       data->udev->dev.removable == DEVICE_FIXED &&
+	       data->udev->parent && data->udev->portnum &&
+	       usb_acpi_power_manageable(data->udev->parent,
+					 data->udev->portnum - 1);
+}
+
 static int btusb_close(struct hci_dev *hdev)
 {
 	struct btusb_data *data = hci_get_drvdata(hdev);
@@ -4595,6 +4605,9 @@ static int btusb_probe(struct usb_interface *intf,
 		hdev->send = btusb_send_frame_intel;
 		hdev->reset = btusb_intel_reset;
 
+		if (btusb_intel_acpi_power_manageable(data))
+			hci_set_quirk(hdev, HCI_QUIRK_NON_PERSISTENT_SETUP);
+
 		if (id->driver_info & BTUSB_INTEL_NO_WBS_SUPPORT)
 			btintel_set_flag(hdev, INTEL_ROM_LEGACY_NO_WBS_SUPPORT);
 
@@ -4912,6 +4925,12 @@ static int btusb_suspend(struct usb_interface *intf, pm_message_t message)
 
 	BT_DBG("intf %p", intf);
 
+	/* reset_resume is only safe for the Intel ACPI path below. */
+	if (PMSG_IS_AUTO(message) &&
+	    (data->udev->quirks & USB_QUIRK_RESET_RESUME) &&
+	    !btusb_intel_acpi_power_manageable(data))
+		return -EBUSY;
+
 	/*
 	 * It is reported that remote wakeup events could sometimes cause some
 	 * adapters completely unresponsive. Resetting the xHCI root hub doesn't
@@ -5076,6 +5095,19 @@ static int btusb_resume(struct usb_interface *intf)
 	return err;
 }
 
+static int btusb_reset_resume(struct usb_interface *intf)
+{
+	struct btusb_data *data = usb_get_intfdata(intf);
+
+	if (!btusb_intel_acpi_power_manageable(data) ||
+	    test_bit(HCI_RUNNING, &data->hdev->flags)) {
+		intf->needs_binding = 1;
+		return 0;
+	}
+
+	return btusb_resume(intf);
+}
+
 #ifdef CONFIG_DEV_COREDUMP
 static void btusb_coredump(struct device *dev)
 {
@@ -5093,6 +5125,7 @@ static struct usb_driver btusb_driver = {
 	.disconnect	= btusb_disconnect,
 	.suspend	= pm_ptr(btusb_suspend),
 	.resume		= pm_ptr(btusb_resume),
+	.reset_resume	= pm_ptr(btusb_reset_resume),
 	.id_table	= btusb_table,
 	.supports_autosuspend = 1,
 	.disable_hub_initiated_lpm = 1,