[Gta04-owner] Developing missing Linux drivers

Dr. H. Nikolaus Schaller hns at goldelico.com
Sun Aug 21 19:40:03 CEST 2011


Am 21.08.2011 um 16:57 schrieb Butrus Damaskus:

>>> I see the most wanted code is the PCM voice path to UMTS modem. I
>>> haven't worked too much with ALSA and don't know many specifics of the
>>> gta04 hardware.
>> 
>> Working on issues relaying to UMTS is still a problem ATM, because
>> we still couldn't make out the NDA for this part.
>> You could watch nearly the entire schematics, except the two pages
>> about UMTS.
> 
> Have You, perhaps, one more raw PCB (i.e. without the chips on them)
> for the developers? ;-)

Unfortunately a bare boards wouldn't help much. It needs very sophisticated
machines to solder the chips. Any buying the chips sometimes isn't easy
as well.

But despite NDA it is no secret that the PCM audio path is connected
to the McBSP4 of the OMAP CPU. They are just 4 wires and the only
hardware bug we can have is that we unexpectedly did cross over
some wires. In that case it could be possible to write a bitbang GPIO driver.
We just have 48 kbit/s sampling rate and this should be possible to sustain
by a 800 MHz CPU.

But it would be better to demonstrate some

	arecord <modem> | aplay <earpiece>&

BTW: we had a similar issue in a earlier engineering sample. In that board
the I2C1 was crossed over and not fixable by cutting some wires. I2C1is
required to control the TPS65950 PMU/Codec. We developed
a bitbang driver (which was horribly slow but worked).

Nikolaus



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