[FSO] add QCT msm7* modem support
Michael 'Mickey' Lauer
mickey at openmoko.org
Sun Nov 23 18:42:31 CET 2008
> > 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?
If you have one channel where you always retrieve unsolicited responses, you
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
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.
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