On Thu, May 07, 2020 at 02:53:36PM +0100, Sean Young wrote:

serio drivers can only send one byte at a time. If the underlying tty
is a usb serial port, then each byte will be put into separate usb
urbs, which is not efficient.

Additionally, the Infrared Toy device refuses to transmit IR if the
IR data is sent one byte at a time. IR data is formatted in u16 values,
and the firmware expects complete u16 values in the packet.

https://github.com/DangerousPrototypes/USB_IR_Toy/blob/master/Firmware-main/IRs.c#L240

Ummm, serial protocol data size is at most 9 bits so I have no earthly
idea how they expect to get 16.

serio is explicitly byte-oriented layer, of you need to exchange
larger data I'd recommend using USB natively maybe?

Thanks.

-- 
Dmitry