UF_DoC
Posts: 49
Joined: Wed Jul 01, 2015 9:00 am

RPi3 USB Modem Rebooting

Sun Apr 02, 2017 8:48 am

Hi Guys,

I have a Raspberry Pi 3 with a USB Modem (Huawei 12d1:1446) E1750.

The modem keeps on resetting every 3-5 seconds as shown in the dmesg logs:

Code: Select all

[  +5.103849] usb 1-1.3: new high-speed USB device number 26 using dwc_otg
[  +0.102347] usb 1-1.3: New USB device found, idVendor=12d1, idProduct=1446
[  +0.000025] usb 1-1.3: New USB device strings: Mfr=3, Product=2, SerialNumber=0
[  +0.000013] usb 1-1.3: Product: HUAWEI Mobile
[  +0.000013] usb 1-1.3: Manufacturer: HUAWEI Technology
[  +0.004346] usb-storage 1-1.3:1.0: USB Mass Storage device detected
[  +0.000524] scsi host34: usb-storage 1-1.3:1.0
[  +0.001082] usb-storage 1-1.3:1.1: USB Mass Storage device detected
[  +0.000309] scsi host35: usb-storage 1-1.3:1.1
[  +0.994053] scsi 35:0:0:0: Direct-Access     HUAWEI   SD Storage       2.31 PQ: 0 ANSI: 2
[  +0.001276] sd 35:0:0:0: Attached scsi generic sg0 type 0
[  +0.000501] scsi 34:0:0:0: CD-ROM            HUAWEI   Mass Storage     2.31 PQ: 0 ANSI: 2
[  +0.003325] sr 34:0:0:0: [sr0] scsi-1 drive
[  +0.001347] sr 34:0:0:0: Attached scsi CD-ROM sr0
[  +0.002502] sd 35:0:0:0: [sda] Attached SCSI removable disk
[  +0.000759] sr 34:0:0:0: Attached scsi generic sg1 type 5
[  +0.696730] usb 1-1.3: USB disconnect, device number 26
This happens over and over.

First I though it to be a PSU issue, but I am using the official 2.5A pi supply and have tried another official PSU, same effect.
I also tried usb_max_current config. but I understand that it has no effect on the Pi3.

Any idea how I can get this modem to work? or has someone used this modem successfully?

epoch1970
Posts: 4204
Joined: Thu May 05, 2016 9:33 am
Location: Paris, France

Re: RPi3 USB Modem Rebooting

Sun Apr 02, 2017 11:54 am

It looks like it is detected as a CD rom.
Google found this for me: https://bugzilla.redhat.com/show_bug.cgi?id=1354142. Looks like "alexhorov" found a udev fix, perhaps you can try that? (I have no idea what usb_modeswitch is.)
"S'il n'y a pas de solution, c'est qu'il n'y a pas de problème." Les Shadoks, J. Rouxel

UF_DoC
Posts: 49
Joined: Wed Jul 01, 2015 9:00 am

Re: RPi3 USB Modem Rebooting

Sun Apr 02, 2017 1:43 pm

I am aware of the fact that these USB dongles come such that they appear to be a CDROM and a Modem.

The CDRom is used to provide the "dongle software" to users normally on a windows machine.

On linux you need to usb_mode_switch to get the dongle into modem mode.

My issue is however before this, I cannot switch successfully as the device is restarting every 3 seconds and not staying attached.

UF_DoC
Posts: 49
Joined: Wed Jul 01, 2015 9:00 am

Re: RPi3 USB Modem Rebooting

Sun Jun 04, 2017 10:29 pm

In the spirit of wrapping things up...

This was eventually pegged down to a faulty modem. a replacement modem worked just fine.
Modems should not be resetting themselves every few seconds!

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