passthrough mode (Directly use GSM Modem from PC

[laforge@…]

In order to make it easy to do gsmd/libgsmd/dialer development on the host PC,
we want something called the 'gsm passthrough mode'.

This basically means that on the host PC, we want to see a virtual serial port
via USB (CDC ACM, /dev/ttyACM0). If a host application talks to that virtual
serial port, it actually talks directly to the GSM Modem.

So what needs to be done, is extend u-boot by a piece of code, which

1) powers up the GSM Modem
2) de-asserts GSM_EN (0) to connect GSM Modem to S3C2410
3) listens to USB control endpoint packets to configure baudrate/... of
GSM-facing S3C2410 UART
4) send incoming characters from UART to USB IN endpoint according to CDC ACM spec
5) send incoming charcters from USB OUT endpoint to UART according to CDC ACM spec

This whole software module is part of u-boot and shall be activated by issuing a
command "neo1973 gsm passthrough" at the u-boot command prompt.

[laforge@…]

I'm not entirely sure if u-boot is really the right location to do this.

Having it in u-boot would make sure that there is no conflict between native
phone gsmd (plus higher level apps) and the passthrough/host access.

Heving it in userspace on linux would mean that the phone could still be used as
a PDA. Also, an userspace implementation could probably even be accessed via
Bluetooth at some later point. Plus it could be extended to just give access to
one of the demultiplexed DLC's, 'sharing' the phone.

Also, having it not in u-boot means we don't need to do a u-boot update (which
is critical).

[laforge@…]

*** Bug 105 has been marked as a duplicate of this bug. ***

[werner@…]

We probably wouldn't want to have to reboot the phone just to use it to
check our mail from a USB-attached notebook anyway. So one more vote
against doing this in u-boot.

[stefan@…]

I send a request for comments to the usb-devel mailling list for extending the
g_serial driver to our needs:

http://marc.theaimsgroup.com/?l=linux-usb-devel&m=117339471429600&w=2

[alphaone@…]

Any news on this topic? Is this still an issue for phase 1?

[laforge@…]

*** Bug 464 has been marked as a duplicate of this bug. ***

[laforge@…]

this has been implemented as of svn rev. 2885.

[anonymous]

Milestone Phase 1 deleted