linux-kernel - Re: better support for EV-DO AC8700 800 M usbserial modem ??

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Message-ID: <20080825154946.GA8628@kroah.com>
Date:	Mon, 25 Aug 2008 08:49:46 -0700
From:	Greg KH <greg@...ah.com>
To:	ctuxer <ctuxer@...il.com>
Cc:	linux-kernel@...r.kernel.org, eerpini@...il.com
Subject: Re: better support for EV-DO AC8700 800 M usbserial modem ??

On Sun, Aug 24, 2008 at 09:41:33AM +0530, ctuxer wrote:
> hi everyone ,
>
> i have been using the EVDO AC8700 modem (usbserial) with kernel 2.6.26.2 , 
> it uses the 'option' module along with the generic usbserial module . Well 
> i am happy for the improved support for the modem handling in the new 
> kernels( like now i don have to modprobe with the vendor and product IDs ) 
> , there is one point specific to this modem which is still not handled , 
> ..... the modem switches between EVDO and CDMA mode when the signal 
> strength is low or when there is a bandwidth overload at the vendor's( the 
> service provider , bsnl in my case )  tower . This switch in the mode is 
> not recognised by the driver and the connection is lost once this switching 
> occurs . I have to restart the wvdial program to reconnect .
>
> But if the modem were in CDMA mode when i connect , then the connection is 
> not lost when the modem switches back from CDMA to EVDO . I really don know 
> enough to understand what is the difference between the two cases or what 
> can be done to improve the support for this usbserial modem , ... can 
> anyone help ?

This looks like something the userspace side has to handle, the option
driver is just a dumb "pass-through" type driver, it doesn't really
control the modem at all.  The "control" channel on the modem allows
this to happen, a userspace program drives this.

good luck,

greg k-h
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