<div dir="ltr">Then, would it be possible to fix a 2G, 3G or 4G with mbimcli after a connection has been established using ModemManager?</div><div class="gmail_extra"> <div class="gmail_quote">On Wed, Oct 28, 2015 at 10:54 PM, Aleksander Morgado <<a href="mailto:aleksander@aleksander.es" target="_blank">aleksander@aleksander.es</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="HOEnZb"><div class="h5">On Wed, Oct 28, 2015 at 10:45 PM, Dan Williams <<a href="mailto:dcbw@redhat.com">dcbw@redhat.com</a>> wrote: > On Wed, 2015-10-28 at 20:06 +0100, Aleksander Morgado wrote: >> On Wed, Oct 28, 2015 at 6:59 PM, Dan Williams <<a href="mailto:dcbw@redhat.com">dcbw@redhat.com</a>> wrote: >> >> > As you can see, there is only one supported mode (allowed: 2g, 3g, 4g; >> >> > preferred: none) which (as far as I know) offers me no contl about >> >> > which network technology is being used. When using this modem with >> >> > other SIM cards or other protocols (this modem also supports QMI, >> >> > direct IP and serial) the supported modes varies. >> >> > >> >> > My understanding is that the supported modes are provided by the modem >> >> > to ModemManager. Which variables affect the supported modes reported? >> >> > >> >> > Is there a way to force ModemManager to use only 2g/3g/4g despite of >> >> > the supported modes reported by the modem? >> >> >> >> I don't recall why it was hardcoded in MM specifically to disallow mode >> >> switching on LTE-capable devices. Aleksander would probably know more. >> >> ModemManager has 2 settings controlling this behavior: capabilities >> and modes. When 4G is enabled in the MC7710 (capabilities >> gsm-umts+lte) the only allowed setting is 2G+3G+4G (auto). If you want >> to set it as 2G+3G (i.e. no 4G) you'll need to switch capabilities to >> just gsm-umts (no lte). Once that is done, the modem will get rebooted >> and you'll now see a new list of mode combinations, including "2G >> only", "3G only", "2G+3G, 3G preferred" and "2G+3G, 2G preferred". >> This behavior is actually very specific to how the MC7710 responds to >> our commands (i..e how we compute the list of supported modes and >> capabilities). Other modems like the MC7304 may not require the power >> cycle to switch capabilities just to get in 2G+3G mode. >> >> This may also give more info: >> <a href="https://sigquit.wordpress.com/2013/06/03/changing-modes-and-capabilities-in-modemmanager/" rel="noreferrer" target="_blank">https://sigquit.wordpress.com/2013/06/03/changing-modes-and-capabilities-in-modemmanager/</a> >> >> As for why we hardcode the values. Well, those are the modes that QMI >> supports. The only confusion here is why you didn't get the 2G+3G >> modes when 4G was also enabled, which I said I believe is very >> specific to the MC7710 if I'm not mistaken. > > My read of the code indicates that we get the same behavior with USB > devices like the UML290 and such too though, right? Which don't have > the same restriction as the MC77xx devices. eg this code block in > modem_load_supported_modes(): > > /* LTE and others, only allow to have all, no further preference */ > else if (mm_iface_modem_is_3gpp_lte (_self)) { > /* 2G, 3G and 4G */ > mode.allowed = (MM_MODEM_MODE_2G | MM_MODEM_MODE_3G | > MM_MODEM_MODE_4G); > mode.preferred = MM_MODEM_MODE_NONE; > g_array_append_val (combinations, mode); > } > > obviously gets run for an LTE-capable modem, even ones that can change > modes around unlike the 77xx devices. </div></div>You're right indeed. When LTE is involved we fix the supported modes. Just checked it with my MC7304: Modes | supported: 'allowed: 2g, 3g, 4g; preferred: none' Not sure why I though it was a MC7710 only thing... bad memory :/ -- Aleksander <a href="https://aleksander.es" rel="noreferrer" target="_blank">https://aleksander.es</a> </blockquote></div> </div>