[FSO] add QCT msm7* modem support

Michael 'Mickey' Lauer mickey at openmoko.org
Sun Nov 23 18:42:31 CET 2008


Hi,

> > Let me add on that -- it is always desirable to have more than just one
> > channel for usual AT commands, that way you can drastically simplify the
> > gsm server logic. I would prefer three independent homogenous command
> > channels, if we can have them, one for call control, one for unsolicited
> > responses, and one for everything else.
>
> Why does it simplify gsm server logic?

Example:
If you have one channel where you always retrieve unsolicited responses, you 
can
a) disable unsolicited responses on the other channels and use them solely in 
request/response mode, and
b) retrieve unsolicited responses while the other channels are busy (e.g. 
during dialing the ATD command hangs and blocks any other commands or 
unsolicited messages coming in)

> What do you mean by independent and homogenous?

Independent: They keep their own state, e.g. if you enable +CREG on channel A, 
it would not get sent on channel B.

Homogenous: Channels are equal, e.g. you the same set of commands work equally 
on channel A and B.

> If you want to change the way you access the modem in the msm7*, you
> must modify the AMSS. It is the software which provides us with the
> shared memory fifos where the serial nodes run on. The kernel driver
> is only a thing that manages the data flow on them and provides the
> devices. So that would be very hard. If I got this wrong and you want
> to make userspace software that "sorts" different commands it's
> something else. But I don't understand the reason. Does it work like
> that on the mokos?

On the TI Calypso, we have soft-multiplexing (done in userland) giving us 4 
independent, homogenous channels. This is a quite nice base for any gsm 
server.
On the Freescale Neptune, we have hard-multiplexing (done in hardware+kernel) 
giving us 8 channels, however they're not independent nor homogenous. Still 
they have something like a dedicated channel for several types of commands 
(i.e. unsolicited), so that's nice as well.

Don't get me wrong, we can use a singleline modem fine as well, but you will 
have to live with certain limitations.

-- 
:M:



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