drivers/libusb1.c: reset driver parameters while enumerating

With an Arduino Leonardo compatible board attached alongside a
CyberPower CP1500PFCLCD, usbhid-ups would incorrectly conclude that
there was no kernel driver attached to the UPS and then fail subsequent
steps accordingly.

The cause is the global usb_communication_subdriver_t struct; when a
subdriver (e.g. arduino-hid) sets different values during the
enumeration loop, they're not set back to defaults afterwards, causing
issues with other subdrivers (e.g. cps-hid).

So, if a subdriver doesn't match, set a selection of fields back to
their default values using the newly added nut_usb_subdriver_defaults()
before the next attempt.

Signed-off-by: Matt Merhar <[email protected]>

NEWS.adoc

@@ -147,6 +147,11 @@ https://github.com/networkupstools/nut/milestone/11
      by default: `powercom_sdcmd_byte_order_fallback`. [PR #2480]
    * `cps-hid` subdriver now supports more variables, as available on e.g.
      CP1350EPFCLCD model. [PR #2540]
+   * USB parameters (per `usb_communication_subdriver_t`) are now set back to
+     their default values during enumeration after probing each subdriver.
+     Having an unrelated device connected with a VID:PID matching the
+     `arduino-hid` subdriver prevented use of an actual `usb-hid` device due to
+     changes made to this struct during probe. [#2611]
 
  - bicker_ser: added new driver for Bicker 12/24Vdc UPS via RS-232 serial
    communication protocol, which supports any UPS shipped with the PSZ-1053

drivers/libusb1.c

@@ -153,6 +153,20 @@ static int nut_usb_set_altinterface(libusb_device_handle *udev)
 	return ret;
 }
 
+static void nut_usb_subdriver_defaults(usb_communication_subdriver_t *subdriver)
+{
+	if (!getval("usb_config_index"))
+		subdriver->usb_config_index = LIBUSB_DEFAULT_CONF_INDEX;
+	if (!getval("usb_hid_rep_index"))
+		subdriver->hid_rep_index = LIBUSB_DEFAULT_INTERFACE;
+	if (!getval("usb_hid_desc_index"))
+		subdriver->hid_desc_index = LIBUSB_DEFAULT_DESC_INDEX;
+	if (!getval("usb_hid_ep_in"))
+		subdriver->hid_ep_in = LIBUSB_DEFAULT_HID_EP_IN;
+	if (!getval("usb_hid_ep_out"))
+		subdriver->hid_ep_out = LIBUSB_DEFAULT_HID_EP_OUT;
+}
+
 /* On success, fill in the curDevice structure and return the report
  * descriptor length. On failure, return -1.
  * Note: When callback is not NULL, the report descriptor will be
@@ -870,6 +884,8 @@ static int nut_libusb_open(libusb_device_handle **udevp,
 			/* if (if_claimed)
 				libusb_release_interface(udev, usb_subdriver.hid_rep_index); */
 			libusb_close(udev);
+			/* reset any parameters modified by unmatched drivers back to defaults */
+			nut_usb_subdriver_defaults(&usb_subdriver);
 	}
 
 	*udevp = NULL;