On Monday 01 August 2011, Dan Williams wrote: > On Mon, 2011-08-01 at 09:26 +0100, Andrew Bird (Sphere Systems) wrote: > > Hi all, > > > > I'm trying to understand the meaning of 'Enable Mobile Broadband' from > > > > the NM applet menu. I have a few questions: > > > > Is the NM applet Enable item just a direct control of the WWAN devices's > > radio function? > > Not necessarily. Enable means "power up the modem and initialize it so > that it is able to be connected at some point in the future." Before > the modem is enabled, it may not be powered up, it may not be registered > with a network, it may not send/receive SMS, etc. Basically, before > anything can be done with the modem beyond detecting that the modem > exists and whether the modem needs a PIN, the modem must be enabled. OK thanks, I understand now
> > a) if so, what happens at startup, is the modem's radio functionality > > > > checked and the Enable checkitem state set accordingly, or is the modem's > > radio forced into some default/remembered NM/MM derived state? > > ModemManager starts all modems in disabled state, and NetworkManager > should not be automatically enabling modems; that's left to the user > because at the moment, most people won't be using their modems full-time > and probably don't want them to suck down power when they aren't > actually being used. It's up to the connection manager (NM or something > else) to determine whether or not to enable the device, and right now NM > requires the user to explicitly make that decision. If you're using an > embedded platform, whatever tells MM to connect probably wants to enable > the modem when that thing starts. OK thanks, I understand now > > > b) if so, what happens if we have two modems (perhaps one is embedded > > and > > > > the other external) and their radios are in different states, or need to > > be? > > MM allows both modems to have different state. With NetworkManager > however, because there isn't a separate rfkill for each WWAN device, > there's a single composite state just like there is for WiFi. If any > modem is disabled, the checkbox (and NM's "WwanEnabled" state) will be > FALSE. If the user checks the box (or something sets WwanEnabled to > TRUE) NM will attempt to call MM's Enable() method for all devices. > > I'm somewhat unclear on use-cases where multiple modems would be > connected to a system under normal conditions where both wouldn't be > able to be enabled at the same time. Thoughts? Yeah it was a contrived example, and the only reason I can think of is power saving on the unused modem. > > > c) if so, does MM prefer to use +CFUN=0 or +CFUN=4 to Disable the > > modem? > > That's left to the modem plugin. CFUN=0 often has the unfortunate > side-effect of actually powering off the device so it's not used on many > devices. CFUN=4 is unfortunately unimplemented on a wide range of > devices, but if it is available we should be using it. Patches for that > would be accepted; we can check CFUN=? on startup and then store the > returned list of available modes and use that to determine whether to > set CFUN=4 on disable. > > > d) if not, what function does Enable on the applet perform? > > Not sure what you're asking here... You answered it in part (a) > > > e) if not, is there another way to turn off the radio, perhaps an > > Aircraft > > > > Mode? > > That is current calling Enable(FALSE) for the modem on the MM DBus > interface, which is supposed to place the modem into low-power mode. > RFKILL/Aircraft mode isn't what we want to do here, because that is > easily confused with the physical button that many laptops have, which > often just disconnects the device from the USB bus completely. Which > means MM can't see it anymore because it doesn't exist. So I think just > having the device disabled via the equivalent of CFUN=4 is sufficient, > and leave actual airplane mode/rfkill to the BIOS, if any. > > Dan There is one thing I noticed though after doing a few tests with NM on Ubuntu Natty. If after first insertion of a device, the user dismisses the PIN entry dialog without authenticating. Then he subsequently uses the nm-applet to enable mobile broadband but it doesn't prompt again for PIN. Which means that to see registration/sig strength/networks etc, the user must first attempt a connection in order to get prompted for PIN and auth, or he must pull the stick and reinsert. Which may be expected behaviour I guess, but a little awkward. Thanks for taking the trouble to explain it all Andrew _______________________________________________ networkmanager-list mailing list [email protected] http://mail.gnome.org/mailman/listinfo/networkmanager-list
