[fprint] How to add UART Fingerprint Scanner support for libfprint

[Charlie Lin]

I have a Waveshare fingerprint scanner that is attached to a USB
breakout board containing a CP2102 USB-UART bridge chip. On the Linux
kernel, plugging the board in creates a USB serial tty.

Aside from setting up tty properties (eg 19200 baud), can I treat the
device like other USB fingerprint sensors supported by libfprint (i.e.
use FpiUsbTransfer)?

Benjamin Berg says no:
> No, you have a UART device in Linux userspace. That is what you need to
> talk to from libfprint. Going through USB would just add one layer of
> indirection and make HW detection more complicated.