Monday, December 29, 2014

Using ftdi_sio with linux kernel 3.12 and up

A few years ago I did post some informations on how to use a Bixolon BCD-1100 or a Epson DM-D110 displays attached via USB to a linux system.

This works fine, unless you upgrade your Linux system to a kernel with version 3.12 or greater.

Since Kernel 3.12 you will see this in the logs:
# dmesg
ftdi_sio: unknown parameter 'vendor' ignored
ftdi_sio: unknown parameter 'product' ignored 

The problem is, that these two parameters where only intended to be used by developers for testing purposes. So they have now been removed from the 3.12 kernel.
But fortunaly, the linux guys did provide a official way to specify the vendor and product ID's.

We can find it in the file: /sys/bus/usb-serial/drivers/ftdi_sio/new_id.
This file contains a pair of vendor and product id, so all we need is to put those values into this file, doing something like this:

/sbin/modprobe ftdi_sio
echo "1208 0780" > /sys/bus/usb-serial/drivers/ftdi_sio/new_id

If you wish to have it automatically configured, just update your /etc/udev/rules.d/50-dmd110.rules file as follows:

ATTR{idProduct}=="0780", ATTR{idVendor}=="1208", RUN+="/sbin/modprobe -q ftdi_sio" RUN+="/bin/sh -c 'echo 1208 0780 > /sys/bus/usb-serial/drivers/ftdi_sio/new_id'",  OWNER="root", MODE="0666"

or for the /etc/udev/rules.d/51-bixolonBCD1100.rules

ATTR{idVendor}=="1504", ATTR{idProduct}=="0011", RUN+="/sbin/modprobe -q ftdi_sio"  RUN+="/bin/sh -c 'echo 1504 0011 > /sys/bus/usb-serial/drivers/ftdi_sio/new_id'",  OWNER="root", MODE="0666"

or for the  /etc/udev/rules.d/52-star-bcd122u.rules
ATTR{idVendor}=="0519", ATTR{idProduct}=="0007", RUN+="/sbin/modprobe -q ftdi_sio"  RUN+="/bin/sh -c 'echo 0519 0007 > /sys/bus/usb-serial/drivers/ftdi_sio/new_id'",  OWNER="root", MODE="0666"

Please note that you still need to use the correct serial port settings.
The bcd122u for example runs at 19200 baud as where most others are using 9600 baud.

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