Set technology preference to chosen type only.

[Aleksander Morgado]

Hey Paul,

On Tue, Feb 14, 2017 at 3:26 PM, Paul Gildea <gildeap at tcd.ie> wrote:
> I am trying to set the device to use a certain technology only, example UMTS
> or LTE. However when I do so there are still other options available.
>
> Example: qmicli -d /dev/cdc-wdm0 --nas-set-system-selection-preference=umts
> and rebooting will give a mode list of umts, lte, td-scdma via  qmicli -d
> /dev/cdc-wdm0 --nas-get-technology-preference instead of just UMTS.
>
> If I then set it to LTE I will get "lte, td-scdma" instead of just LTE. Is
> there something I am missing? I will check the code further to try and solve
> this.

Would be good to get debug logs of all commands you use (run them with
--verbose), just to make sure the messages sent/received are the
expected ones.

Note that technology preference (TP) and system selection preference
(SSP) are two ways of trying to get the same result. In ModemManager
we use SSP when available, and TP otherwise. Also note that there is a
"NAS Set Technology Preference" command in QMI, we just didn't
implement a --nas-set-technology-preference.

For reference, this is what I'm getting when setting preference to
umts vs LTE in a MC7455:

(set LTE as preferred)

$ sudo qmicli -d /dev/cdc-wdm4 --nas-get-system-selection-preference
Emergency mode: 'no'
Mode preference: 'umts, lte'
Band preference: 'wcdma-2100, wcdma-pcs-1900, wcdma-dcs-1800,
wcdma-1700-us, wcdma-850-us, wcdma-900'
LTE band preference: '1, 2, 3, 4, 5, 7, 8, 12, 13, 20, 25, 41'
TD-SCDMA band preference: '(null)'
Roaming preference: 'any'
Network selection preference: 'automatic'
Service domain preference: 'cs-ps'
Service selection preference: 'automatic'

$ sudo qmicli -d /dev/cdc-wdm4 --nas-get-technology-preference
Active: 'auto', duration: 'permanent'

$ sudo qmicli -d /dev/cdc-wdm4 --nas-set-system-selection-preference="lte"
$ sudo qmicli -d /dev/cdc-wdm4 --dms-set-operating-mode=offline
$ sudo qmicli -d /dev/cdc-wdm4 --dms-set-operating-mode=reset

(reboots)

$ sudo qmicli -d /dev/cdc-wdm4 --nas-get-system-selection-preference
Emergency mode: 'no'
Mode preference: 'lte'
Band preference: 'wcdma-2100, wcdma-pcs-1900, wcdma-dcs-1800,
wcdma-1700-us, wcdma-850-us, wcdma-900'
LTE band preference: '1, 2, 3, 4, 5, 7, 8, 12, 13, 20, 25, 41'
TD-SCDMA band preference: '(null)'
Roaming preference: 'any'
Network selection preference: 'automatic'
Service domain preference: 'cs-ps'
Service selection preference: 'automatic'

$ sudo qmicli -d /dev/cdc-wdm4 --nas-get-technology-preference
Active: '3gpp, lte', duration: 'permanent'


(set umts as preferred)

$ sudo qmicli -d /dev/cdc-wdm4 --nas-set-system-selection-preference="umts"
$ sudo qmicli -d /dev/cdc-wdm4 --dms-set-operating-mode=offline
$ sudo qmicli -d /dev/cdc-wdm4 --dms-set-operating-mode=reset

$ sudo qmicli -d /dev/cdc-wdm4 --nas-get-system-selection-preference
Emergency mode: 'no'
Mode preference: 'umts'
Band preference: 'wcdma-2100, wcdma-pcs-1900, wcdma-dcs-1800,
wcdma-1700-us, wcdma-850-us, wcdma-900'
LTE band preference: '1, 2, 3, 4, 5, 7, 8, 12, 13, 20, 25, 41'
TD-SCDMA band preference: '(null)'
Roaming preference: 'any'
Network selection preference: 'automatic'
Service domain preference: 'cs-ps'
Service selection preference: 'automatic'

$ sudo qmicli -d /dev/cdc-wdm4 --nas-get-technology-preference
Active: '3gpp, cdma-or-wcdma', duration: 'permanent'

-- 
Aleksander
https://aleksander.es