Comment # 4 on bug 1092839 from Stanislav Brabec

Maintainer of brttty is Ruediger Oertel. Reassigning.

The problem is indeed the USB id. USB id 10c4:ea60 is registered in
brltty-5.5/Autostart/Udev/rules. 10C4:EA80 has the same problem:

# Device: 10C4:EA60
# Generic Identifier
# Vendor: Cygnal Integrated Products, Inc.
# Product: CP210x UART Bridge / myAVR mySmartUSB light
# BrailleMemo [Pocket]
# Seika [Braille Display]
ENV{PRODUCT}=="10c4/ea60/*", ENV{BRLTTY_BRAILLE_DRIVER}="mm,sk",
GOTO="brltty_usb_run"

# Device: 10C4:EA80
# Generic Identifier
# Vendor: Cygnal Integrated Products, Inc.
# Product: CP210x UART Bridge
# Seika [Note Taker]
ENV{PRODUCT}=="10c4/ea80/*", ENV{BRLTTY_BRAILLE_DRIVER}="sk",
GOTO="brltty_usb_run"


According to kroesche from Silicon Labs, the correct assignment for these two
USB ids are: 

10C4:EA60 CP210x UART Bridge
https://usb-ids.gowdy.us/read/UD/10c4/ea60

10C4:EA80 CP2110 HID UART Bridge
https://usb-ids.gowdy.us/read/UD/10c4/ea80

So this is cleanly a fault of Braille device manufacturer. Vendor ignored rules
and released their devices with the unchanged default UART Bridge USB id. They
even did not request custom product id from Silicon Labs.
https://www.silabs.com/products/interface/request-product-id

brltty udev rule either has to add a helper to identify the Braille device
(without breaking of other serial devices), or we have to live with a Braille
device that does not work out of the box and needs configuration.

As CP210x are very common, it is even possible that brltty udev configuration
would require to configure exact USB connector. Otherwise the user of Braille
device would not be able to use a wide set of devices (GPSes, AVR programmers,
serial converters etc.).