Prevent 3G modem from presenting as a CD-ROM drive

Robhogg · 06-05-2010, 10:52 AM

I am just trying out Ubuntu 10.04, and using an Huawei E220 3G/HSDPA modem for my internet connection. I have found that, whenever I start Rhythmbox, it causes my internet connection to drop.

I believe that this is caused by Rhythmbox trying to read the modem as a CD-ROM drive. Until I changed the settings, Gnome was displaying an icon for the device as a volume on the desktop and double-clicking this would also cause the connection to be lost. However, if I use modprobe -r to remove the usb-storage module, I can launch Rhythmbox without problems.

The device is capable of presenting in either CD-ROM or modem mode, and relies on a driver to switch the mode. Older kernels (pre-2.6.20) required a utility to do this. In Debian, under the 2.6.26 kernel, and an older (9.04, I think) version of Ubuntu netbook remix, it seems to work fine. However, Ubuntu with the 2.6.32 kernel still seems to be holding on to the impression that it is a CD-ROM (even though it works as a modem).

In the output of dmesg, there are reports of hardware errors for the "CD-ROM" device, but I am wondering if this is just because it is trying to treat it as the wrong type of device:

Code:

[  388.214174] usb-storage: waiting for device to settle before scanning
[  388.218209] usbcore: registered new interface driver usbserial
[  388.218601] USB Serial support registered for generic
[  388.218707] usbcore: registered new interface driver usbserial_generic
[  388.218710] usbserial: USB Serial Driver core
[  388.222822] USB Serial support registered for GSM modem (1-port)
[  388.223047] option 2-1:1.0: GSM modem (1-port) converter detected
[  388.223569] usb 2-1: GSM modem (1-port) converter now attached to ttyUSB0
[  388.223593] option 2-1:1.1: GSM modem (1-port) converter detected
[  388.223764] usb 2-1: GSM modem (1-port) converter now attached to ttyUSB1
[  388.223797] usbcore: registered new interface driver option
[  388.223799] option: v0.7.2:USB Driver for GSM modems
[  393.214296] usb-storage: device scan complete
[  393.217275] scsi 5:0:0:0: CD-ROM            HUAWEI   Mass Storage     2.31 PQ: 0 ANSI: 2
[  393.240201] sr1: scsi-1 drive
[  393.240498] sr 5:0:0:0: Attached scsi CD-ROM sr1
[  393.241237] sr 5:0:0:0: Attached scsi generic sg2 type 5
[  403.125212] sr1: CDROM (ioctl) error, command: Xpwrite, Read disk info 51 00 00 00 00 00 00 00 02 00
[  403.125246] sr: Sense Key : Hardware Error [current] 
[  403.125256] sr: Add. Sense: No additional sense information
[  405.146170] sr1: CDROM (ioctl) error, command: Get configuration 46 00 00 00 00 00 00 00 20 00
[  405.146203] sr: Sense Key : Hardware Error [current] 
[  405.146213] sr: Add. Sense: No additional sense information
[  405.282167] sr1: CDROM (ioctl) error, command: Get configuration 46 00 00 00 00 00 00 00 20 00
[  405.282199] sr: Sense Key : Hardware Error [current] 
[  405.282210] sr: Add. Sense: No additional sense information
[  409.232499] PPP BSD Compression module registered
[  409.252637] PPP Deflate Compression module registered

Has anyone come across this before, and any suggestions?

Many thanks,
Rob.

mazinoz · 06-05-2010, 06:48 PM

I could only get an old E220 Huawei modem to work as a modem by running a script to disable usb-storage part of the modem before connecting to ISP. I believe the problem has been around for a long time, this was using Debian Lenny or older though. I connected using /etc/ppp/peers scripts. Alternatively you could use kppp or gnome-ppp perhaps. The only other thing I can suggest is to dig around in the kernel settings perhaps?