On Wed, 2013-08-14 at 11:43 -0500, Peter Hyman wrote:
> Linux Kernel: 3.9.10
> Device Driver: usb/serial/sierra.c
> Device Driver version: not known
> 
> Apparently Sierra has sold the AirCard 250U product to Netgear, so I am
> sure driver development on drivers/usb/serial/sierra.c will be in limbo
> for a period. While I am copying li...@sierrawireless.com, they will not
> do anything since they don't own the product anymore.
> 
> Nonetheless, I uncovered a problem when using the AC250U Aircard device
> Vendor 0x1199, Product 0x0301. If the device is used in Windows and set
> to 4G mode, using the device in Linux will fail to create the ppp0
> network interface. I could find no workaround. Even though the device
> can be reached and modem commands sent, ppp0 won't be created. I
> regression tested this all the way back to kernel 3.2.29, and I also
> tried the unpublished sierra driver 1.7.40 which works up to kernel
> 3.4.x iirc. The issue is the same.

The 4G part of the 250U is a Beceem WiMAX chip, for which there are no
drivers on Linux at this time.  The 4G parts are used with a
pseudo-ethernet interface, but since there aren't any kernel drivers,
that's not going to work.  The 4G parts do not use PPP.

The 3G part, however, *does* use PPP over the serial ports.

So with this information, it's not surprising that when you choose "4G
Only" in Windows, the 3G part (eg, PPP over serial ports) isn't going to
work on Linux.

Dan

> The workaround is to set the device to 3G mode and then use in Linux. I
> wrote this FAQ in case it is of interest.
> =====
> FAQ: ppp0 Network Interface does not get created after plugging AirCard
> 250U device when using Linux. No internet access is possible without the
> ppp0 network interface.
> 
> Answer: If the AC250U device is used in Windows, and is set to 4G mode
> by the Sprint SmartView software, it MUST be set back to 3G mode prior
> to use in Linux. The Linux Sierra driver does not support 4G and the
> device won't be able to be initialized properly. It will be recognized
> and you can send modem commands, but the ppp0 device won't be created.
> Reset device to 3G under Windows and it will work fine in Linux.
> =====
> 
> Maybe a nice feature request would be to check the 3G/4G status of the
> device and reset to 3G since that is what is supported for now. If you
> need additional information, please reach out. Happy to help.
> 
> usb 4-1.2.2: New USB device found, idVendor=1199, idProduct=0301
> usb 4-1.2.2: New USB device strings: Mfr=1, Product=2, SerialNumber=4
> usb 4-1.2.2: Product: Sierra Wireless Device
> usb 4-1.2.2: Manufacturer: Sierra Wireless, Incorporated
> usb 4-1.2.2: SerialNumber: 4Vx«Ãïÿÿÿÿ
> usbcore: registered new interface driver usbserial
> usbcore: registered new interface driver usbserial_generic
> usbserial: USB Serial support registered for generic
> usbcore: registered new interface driver sierra
> usbserial: USB Serial support registered for Sierra USB modem
> sierra 4-1.2.2:1.0: Sierra USB modem converter detected
> usb 4-1.2.2: Sierra USB modem converter now attached to ttyUSB0
> usb 4-1.2.2: Sierra USB modem converter now attached to ttyUSB1
> usb 4-1.2.2: Sierra USB modem converter now attached to ttyUSB2
> usb 4-1.2.2: Sierra USB modem converter now attached to ttyUSB3
> 


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