Re: [MM master] Re: [MM06] [PATCH] sierra: use +CFUN=4 for powering down

[Aleksander Morgado <aleksander lanedo com>]

>>>>>>>> See patch attached.
>>>>>>>>
>>>>>>>> sierra: use +CFUN=4 for powering down
>>>>>>>>
>>>>>>>>     plugins/mm-modem-sierra-gsm.c |   32
>>>>>>>> ++++++++++++++++++++++++++++++++
>>>>>>>>     1 file changed, 32 insertions(+)
>>>>>>> This also needs to be intregrated in the master branch version.
>>>>>>> Attached
>>>>>>> is my attempt to do it, but it seems not to work. I see no effect of
>>>>>>> disabling the modem with "mmcli -m X -d".
>>>>>> See review below.
>>>>>>
>>>>>>> Also, it seems like the power down is not done before the modem
>>>>>>> enters
>>>>>>> disabled state at startup of MM or after modem is inserted, so I
>>>>>>> filed a
>>>>>>> bug about that:
>>>>>>>
>>>>>>> https://bugzilla.gnome.org/show_bug.cgi?id=683681
>>>>>>>
>>>>>> Yes, that's a known issue, see TODO in the source tree.
>>> The text there is slightly incorrect. It does not help if the modem is
>>> in low power mode when started (some might also be configured to be),
>>> because at least in the Sierra plugin, it is waked up to CFUN=1 in the
>>> init anyway. This could be avoided by accepting CFUN mode 4 and 7 as
>>> well. But then it must be changed to mode 1 when connecting.
>>>
>>> I am not sure if all the init steps are possible in low power mode.
>>>
>> CFUN=1 is sent when *enabling* the modem, not during init. All the init
>> steps should really be possible while in CFUN=4 low power mode as that
>> should only kill the radio power.
> 
> Sorry, I did not test it or dig deep enough in the code. If I sent the
> modem to CFUN=4, it actually keeps this state after the init, and
> enabling works fine.
> 
>>
>> Also, for Sierra modems there's the problem that CFUN=1 may actually
>> reboot the modem, so the problem with powering down the radio with
>> CFUN=4 in Sierra is that this may require a reboot/reprobing of the
>> modem afterwards :-/ IIRC Wavecom (which also suffers from the same
>> issue) had a CFUN=1,0 to try to go into full functionality mode without
>> rebooting, not sure if Sierra has something similar.
> 
> Seems my Sierra modem has the same:
> 
> +CFUN: (0-1,4-7),(0-1)
> 
> but the default is ",0" on my modem, as "CFUN=1,1" behaves just like
> "CFUN=1", but "CFUN=1,1" causes a restart.
> 
> We could do a detection of the right version by using some regex of the
> CFUN=? output.
> 

Or, just try first with AT+CFUN=1,0 and if we get any error, retry with
the original AT+CFUN=1. This can easily be done with an AT sequence.
Note that anyway the power-up command needs to be sent *only* if not
already in the full-functionality mode (that's why the Sierra and
Wavecom plugins have already the AT+CFUN? check).

-- 
Aleksander