Wrong usb driver is attached at power up

[Lucas Li]

Hi

I have an OCG-EV2 modem which does ppp through ttyUSB0. I also have a ftdi_sio usb-to-2-serial device that is plugged in to the usb host port next to the ethernet connection. If I plug this usb device roughly 30 secs after the modem powers up, then everything works fine. However, if I leave the usb device plugged in before power up, sometimes the ttyUSB0 is loaded with the ftdi_sio driver instead of the sierra wireless driver. In which case, the modem can no longer do ppp. How to ensure that the ttyUSB0 is always used for ppp and not someother device.

As always, thank you for your feedback.

Lucas

[Jesse Gilles]

Hi Lucas,

I’ve actually just made changes to address this type of issue. It can be fixed by adding udev rules that gives the modem a consistent name, even if the ttyUSB port name changes.

See commit:

http://git.multitech.net/cgi-bin/cgit.cgi/corecdp.git/commit/?id=8efda18df6ac54debdf651c7b9359ff04acd47af

This will be included in the next release of CoreCDP, which is currently in testing, but you are free to try the changes now.

If you use the rules from that commit, you can then set your ppp options file to use /dev/modem_at0 and that name will always point to the correct modem port.

Jesse

[Lucas Li]

Great, perfect timing on my part to ask this :). I been trying to write rules for the ftdio_sio usb device thinking I need to change that away from ttyUSB0. But I understand now.

Thanks you

Lucas

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