Matching USB modems on serial.port

Adrian Cox adrian at humboldt.co.uk
Thu Jan 29 02:32:38 PST 2009


I'm working on HAL support for an unreleased 3G modem. I've noticed that a lot of the USB modems in 10-modem.fdi match against the "serial.port" key, including ones recently added such as this patch:

http://cgit.freedesktop.org/hal-info/commit?id=3da37e0ebef1bcd4fd57e6745ef4c85d26f335f7

Is this correct? My testing indicates that the "serial.port" key changes depending on the plugging order, and what other devices are attached. For example, my modem implements four serial ports. If I plug it in once, they are assigned serial.port values of 0,1,2,3. If I open /dev/ttyACM1 with a terminal program, unplug the modem (terminal still open), then replug the modem the serial.port values change to 0,2,3,4.

If I only match the modem on "@info.parent:usb.interface.number" the HAL behavior is correct in the unplug and replug scenario above.

-- 
Adrian Cox <adrian at humboldt.co.uk>


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