It seems that there is new and old revision of CH340.

It seems that there is new and old revision of CH340.
Previous uchcom(4) driver targeted old one, and new one could not work
because of uchcom_set_line_control() broke the value of
UCHCOM_REG_LCR1(0x18).

To support new CH340, uchcom_set_line_control() and uchcom_reset_chip()
have been overhauled. Current uchcom(4) does not change the value of
UCHCOM_REG_LCR1 register, it means even/odd parity mode is no longer
supported with old CH340.

ok by mpi@