Purchased a four-port Keyspan USB/Serial converter to drive various RS232 serial devices via my home automation controller. Conveniently enough, Debian no longer includes the firmware for these devices due to licensing concerns (see DFSG). As of the time this article was written, the firmware was not included in the firmware-nonfree package available via apt. Fortunately, the files *ARE* included in the standard Linux kernel, and can be easily fetched and installed via git.
mh@misterhouse: mh $ aptitude install git-core mh@misterhouse: mh $ mkdir firmware && cd firmware mh@misterhouse: firmware $ git clone git://git.kernel.org/pub/scm/linux/kernel/git/dwmw2/linux-firmware.git mh@misterhouse: firmware $ sudo mkdir /lib/firmware/keyspan mh@misterhouse: firmware $ sudo cp linux-firmware/keyspan/* /lib/firmware/keyspan/
Simply unplugging and re-inserting the device should then allow the driver to find the firmware and properly initialize the adapter.