Hi kindx
1) MMC is compatible with SD interface up to 4 bit mode... I still believe that it is possible two bypass the internal MMC with the internal interface with some resistor swapping, just to find them...
donc want to predate the pci-e, dont want to loose the 3G connectivity.
2) Im pretty sure with your comment on the 3G module that the mini-pci lines are not used and just the USB is available...
I am way to used to old 3G/GSM designs in which the BB was connected through usb and then the connection to the RF was done with SPI. In Amazon's design the MXC does not seem to be in a SOC with a sc3xxx DSP, so it directly uses the USB to connect to the SPRINT/HSDPA module on the pci-express lines... no need to use SPI from the MXC
On my defense, i am too afraid of opening my own DXi so all my guesses are based in SW and experience..., I'd rather buy a broken one from ebay when available...
3) Actually the device you told about is the PM, and it not only controls regulators, but the audio codec, the usb port, the charger, ...
To enable OTG, and even the RS232 passthough, you need to issue some commands over the SPI channel to modify its configuration.
I need to dig a bit to get the specs... but it may be doable.
Still no idea what driver to use, but could be fun
