Modem configurations
====================

If you would like to build our Magnetite firmware in the AT-command-controlled
modem configuration (not the C-Sample UI demo on the Mot C139), you have 3
specific configurations to choose from, differing in the level of deblobbing:

classic		This configuration replicates classic TCS211, just like
		leo2moko from 2013.  Almost all of the original binary blob
		libraries are used; the only components that are recompiled
		from source are those which we got in source form with our copy
		of TCS211 from Sotovik.  This config can only be built for the
		fcdev3b and gtamodem targets, not for c139 or pirelli.

l1reconst	In this configuration most of L1 (GSM Layer 1) is recompiled
		from reconstructed source, although this deblobbing of L1 is
		not 100% complete yet: for the GPRS-specific L1 modules the
		original binary object blobs are still used.  Some housekeeping
		pieces are also recompiled from source that had to be
		reconstructed.  This config can be built for all targets.

hybrid		This configuration is a TCS2/TCS3 hybrid.  Instead of using the
		TCS211 version of the G23M protocol stack which we got only as
		binary blobs, this config uses the G23M PS version from the
		TCS3.2/LoCosto source, backported to work with L1 and the fw
		foundation layers from TCS211.  ACI also had to be replaced with
		the TCS3 version, and a special hybrid version of the cdginc
		headers had to be constructed.  L1 is also deblobbed to the
		same extent as in l1reconst.  Like l1reconst, this config can
		be built for all targets, and it is currently the most deblobbed
		(closest to full source) Magnetite config.

All 3 of the above configurations have CSD, fax and GPRS enabled; this
functionality can only be exercised on those hardware targets on which both
Calypso UARTs are brought out, with the MODEM UART presenting a standard ASCII
AT command interface including data functions, while the IrDA UART carries the
RVTMUX interface for debug trace and other development functions.  If you are
interacting with your Calypso target modem or pseudo-modem solely through
RVTMUX, without access to the ASCII AT command interface on the dedicated MODEM
UART, then the data functions of the firmware are inaccessible and act as dead
weight.

Having deblobbed all of L1 except GPRS-specific modules, we are now in a
position where we can build a hybrid config with GPRS excluded, optionally
including or excluding FAX_AND_DATA, but I (Mychaela) would like to thoroughly
exercise the hybrid config in its current everything-enabled state before making
further changes to it.

The deblobbing of L1 has been done in a very meticulous manner, ensuring that
each individual reconstructed C module compiles into a strict functional
equivalent of the original binary blob, sometimes even matching bit for bit -
thus no regressions are expected with the classic->l1reconst transition, and no
extensive testing is deemed necessary beyond the basic tests that have already
been done.  However, the transition from l1reconst to hybrid involves wholesale
replacement of two major firmware components (G23M PS and ACI) and some
important associated support pieces with entirely different versions from a
different TI program, hence extensive testing and debugging will be needed.

So far the most-deblobbed hybrid config looks very promising: after fixing the
hideous bug resulting from the addition of A5/3 support in TCS3.2 (hardware
feature available on LoCosto but not on Calypso), voice calls work perfectly,
both with the legacy codecs and with AMR!  (The same A5/3 bugfix has also been
applied to our Citrine fw, hence the latter now has working voice calls too.)
However, it is almost certain that there are a ton of minor bugs which need to
be shaken out, hence this firmware build config should be treated as
experimental for the time being, not production.