> > I have some questions about ofono and the data disconnection. > > With debug information, after that my modem is online (connected to network via ppp0 interface), when I go back to offline (by setting online property to false), I can see that the modem network connection is down with : > ofonod[1039]: Modem: < ~\377}#\300!}%}#} }$\205r~ > > and PPP interface is removed : > ofonod[1039]: udevng.c:remove_device() /sys/devices/virtual/net/ppp0 > > I searched how ofono stops the modem connection, with escape sequence for example, but ofono does not seem to use it during offline sequence. > In this case the ofono_gprs_context atom is being created in post_online state. Since you go offline, the modem goes back to post_sim state and any atoms created in post_online() are destroyed. E.g. the atom's remove() method is called. This removes all PPP processing from the chat and forces it back into AT command mode.

There was a similar thread recently about SIM Removal on HE910 exhibiting similar behavior. In that case the modem went back to pre_sim state, so all post_sim and post_online atoms were destroyed.

> How does ofono handles it ? Solution is to put gprs_context creation into pre_sim on modems that reply to CFUN=4 or equivalent before sending the final PPP frame. > How ofono (or gatppp, maybe ?) puts the modem network connection down (if it does) ? > oFono detects PPP end-of-session frames as well as the NO CARRIER result code. See gatchat/gathdlc.c new_bytes() and g_at_hdlc_set_no_carrier_detect()