[Gta04-owner] Replicant modem suspend behavior

[Sebastian Krzyszkowiak]

On Fri, Dec 12, 2014 at 6:11 PM, Lukas Maerdian <luk at slyon.de> wrote:
> Am 12.12.2014 um 16:41 schrieb Rico Rommel:
>> Am Freitag, 12. Dezember 2014, 16:17:54 schrieb Lukas Maerdian:
>>> Hello everybody,
>>>
>>> since quite some time I'm trying to debug the Replicant modem suspend
>>> behavior, but I cannot find any solution...
>>>
>>> My problem is that the modem transitions into a strange state after a
>>> suspend/resume cycle, where it just returns the CME error 0 (phone
>>> failure) to every single AT command I send. If I kill/restart the Radio
>>> Interface Layer ("killall rild"), the modem seems to be working fine
>>> again, so I guess a "AT+CFUN=0; AT+CFUN=1" correctly resets the modem.
>>
>> I don't know if it's related to this or a bug in my phonesoftware, but on
>> resume my phone switches automatically to airplane mode. So I have to set
>> operating mode everytime the phone resumes.
>> I use kernel 3.12 and can't remember, if this problem also existed with kernel
>> 3.7.
>
> Hi Rico,
>
> indeed this seems to be the case! I'm on 3.12 as well and directly after
> resume everything is fine (CFUN: 1) but about 1 sec after the resume I
> receive a "+CREG: 0" URC and if I issue "AT+CFUN?" afterwards I receive
> a "+CFUN: 4", i.e. airplane mode.
>
> So, after this I can simply switch airplane mode off (AT+CFUN=1) and the
> device will be back online! Well... the 3G connection still needs to be
> re-configured, but this is another issue.
>
> Thanks a bunch, this was the missing piece I was looking for!
>
> I assume the modem is still operational during suspend, i.e. is able to
> receive calls/SMS and interrupt the CPU, can you confirm this?
>
> Best,
>   Lukas

Gee, I tried to debug it a few times, but always thought it was some
FSO issue - so no wonder that I failed. Never even thought that it
could be on lower layer!

That explains a lot. Now let's find out why it happens at all :)

Thanks!
-- 
Sebastian Krzyszkowiak, dos
http://dosowisko.net/