../../core/usb/usb.c: In function ‘usb_process_period’:
../../core/usb/usb.c:277:14: warning: unused variable ‘entry’ [-Wunused-variable]
     uint32_t entry = mem_peek(usb.regs.hcor.periodiclistbase + (usb.regs.hcor.frindex & (USBCMD_FRLIST_BYTES(usb.regs.hcor.usbcmd) - 1) << 3), 4);
              ^~~~~
../../core/usb/usb.c: In function ‘usb_hotplug’:
../../core/usb/usb.c:1052:52: warning: unused parameter ‘ctx’ [-Wunused-parameter]
 static int LIBUSB_CALL usb_hotplug(libusb_context *ctx, libusb_device *dev, libusb_hotplug_event evt, void *data) {
                                                    ^~~
../../core/usb/usb.c:1052:109: warning: unused parameter ‘data’ [-Wunused-parameter]
 ibusb_context *ctx, libusb_device *dev, libusb_hotplug_event evt, void *data) {
                                                                         ^~~~
../../core/usb/usb.c: In function ‘init_libusb’:
../../core/usb/usb.c:1114:5: error: implicit declaration of function ‘libusb_set_option’; did you mean ‘libusb_get_version’? [-Werror=implicit-function-declaration]
     libusb_set_option(usb.ctx, LIBUSB_OPTION_LOG_LEVEL, LIBUSB_LOG_LEVEL_INFO);
     ^~~~~~~~~~~~~~~~~
     libusb_get_version
../../core/usb/usb.c:1114:32: error: ‘LIBUSB_OPTION_LOG_LEVEL’ undeclared (first use in this function); did you mean ‘LIBUSB_ERROR_NO_MEM’?
     libusb_set_option(usb.ctx, LIBUSB_OPTION_LOG_LEVEL, LIBUSB_LOG_LEVEL_INFO);
                                ^~~~~~~~~~~~~~~~~~~~~~~
                                LIBUSB_ERROR_NO_MEM
../../core/usb/usb.c:1114:32: note: each undeclared identifier is reported only once for each function it appears in
../../core/usb/usb.c: In function ‘libusb_status_from_error’:
../../core/usb/usb.c:449:1: error: control reaches end of non-void function [-Werror=return-type]
 }
 ^
../../core/usb/usb.c: In function ‘usb_write’:
../../core/usb/usb.c:901:13: warning: this statement may fall through [-Wimplicit-fallthrough=]
             usb_write_reg_masked(&usb.regs.iep[index & 7], 0xFFFF, value, bit_offset);
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../core/usb/usb.c:902:9: note: here
         case 0x180 >> 2: case 0x184 >> 2: case 0x188 >> 2: case 0x18C >> 2:
         ^~~~
At top level:
../../core/usb/usb.c:276:13: warning: ‘usb_process_period’ defined but not used [-Wunused-function]
 static void usb_process_period(void) {
             ^~~~~~~~~~~~~~~~~~
../../core/usb/usb.c:192:13: warning: ‘usb_process_async’ defined but not used [-Wunused-function]
 static void usb_process_async(void) {
             ^~~~~~~~~~~~~~~~~
../../core/usb/usb.c:142:13: warning: ‘usb_event_old’ defined but not used [-Wunused-function]
 static void usb_event_old(enum sched_item_id event) {
             ^~~~~~~~~~~~~
cc1: some warnings being treated as errors
Makefile:1112: recipe for target 'usb.o' failed
make: *** [usb.o] Error 1