Re: Connection to a 3G USB Module using USB-Serial

[Greg KH <greg-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>]

On Thu, May 30, 2013 at 02:54:40PM +0200, Fabio Fumi wrote:
> I'm struggling with this issue since a while and as the author of the
> USB-Serial module I thought experts here might provide some help... As
> it's a USB-serail issue, I've posted on both USB and Serial lists.
> thanks in advance!
> 
> The problem is about connecting with a 3G USB modem, a ZTE MF-210
> mini-pci board; plugged as a daughter board inside an Android tablet.
> I have posted already on a couple forums, but got no useful feedback
> yet.
> 
> As soon as I power up the module I get the expected /dev/ttyUSB0-3 and
> that's fine, so far:
> 
> <6>usb 1-1.1: new high speed USB device using emxx-ehci-driver and address 3
> <6>option 1-1.1:1.0: GSM modem (1-port) converter detected
> <6>usb 1-1.1: GSM modem (1-port) converter now attached to ttyUSB0
> <6>option 1-1.1:1.1: GSM modem (1-port) converter detected
> <6>usb 1-1.1: GSM modem (1-port) converter now attached to ttyUSB1
> <6>option 1-1.1:1.2: GSM modem (1-port) converter detected
> <6>usb 1-1.1: GSM modem (1-port) converter now attached to ttyUSB2
> <6>option 1-1.1:1.3: GSM modem (1-port) converter detected
> <6>usb 1-1.1: GSM modem (1-port) converter now attached to ttyUSB3
> 
> Issue is when I try to communicate with any of these ports. I can
> connect using picocom to all but can't receive any feedback from AT
> commands sent over to them. I made some partial progress only after
> using the "-i" option (i.e. "no port init"), but below you can find
> what I get if I simply type A + T + Z + <enter>, for example.
> 
> As you can see, characters and commands are repeated several times.
> That's what I can't understand.
> 
> Without the -i option, I don't even get any feedback from the modem
> and the same happens using other connection programs, e.g. busybox
> microcom. I'm using picocom as it's very small and I succesfully used
> it already in a similar case, though on a different Android platform
> and kernel.
> 
> This Kernel is built including standard usb-serial options below:
> 
> CONFIG_USB_SERIAL=y
> CONFIG_USB_SERIAL_WWAN=y
> CONFIG_USB_SERIAL_OPTION=y

What kernel version are you using?

> Is the kernel missing anything, or requiring some special ZTE-specific
> customizations in your opinion?

There is a new zte-specific driver in the 3.9 kernel release that should
work for your device.  We just got some patches merged that moved the
device id from the option driver to the zte driver, which should resolve
issues like the one you are seeing here (i.e. the wrong driver
controlling the device.)  Can you test the 3.10-rc5 kernel that comes
out in a few days, or the next 3.9-stable release 3.9.6 should have the
proper patches)?

thanks,

greg k-h
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