libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
for (i = 0; devlist[i]; i++) {
libusb_get_device_descriptor(devlist[i], &des);
libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
for (i = 0; devlist[i]; i++) {
libusb_get_device_descriptor(devlist[i], &des);