PN533 easily corrupts its USB descriptors. We know that and we
already try to detect and even repair them.
However there are situations where lower software layers get
confused before libnfc can help. On Windows, libusb may set
dev->config to NULL, but we can also have a non NULL dev->config
referencing corrupted data.
In order to get more robust, let us replace the Windows libusb
specific (dev->config == NULL) test by an inconditionnal use of
hardcoded descriptors when they are available.
After a DESfire operation SCL3711 will sometimes enter a state where
libusb-0.x is unable to fill config field in struct usb_device. The
USB device has to be power-cycled to restore a sane state.
This introduce a work around, by using hardcoded values for endpoints
and packet size when they are unavailable.
Emmanuel Dreyfus