[Letux-kernel] Modem disappears GTA04A4

[H. Nikolaus Schaller]

Hi,

> Am 13.01.2019 um 23:28 schrieb Jake <jake42 at rommelwood.de>:
> 
> Hi,
> 
> I'm experiencing a problem with the modem disappearing on GTA04.
> For example when writing text messages to and fro with suspends in
> between it happens at times, that the modem /dev/ttyHS* files
> disappear.

That is a known bug [1] in the modem firmware but unfortunately we
did never get a better one.

> The modem is still unblocked in rfkill. 
> 
> I don't have any logs yet. I usually powered off the GTA04A4, removed
> the battery for a few seconds, reinserted and booted again to continue
> the conversation as soon as possible.
> 
> How can I toggle the gpio 186? to reenable the modem manually?

"rfkill block wwan; sleep 0.5; rfkill unblock wwan" should do it.

> 
> My observations so far:
> 4.19-rc7: modem disappears sporadically
> 4.19.12: modem disappears sporadically
> 4.20: does not wake on incoming call/text
> 4.18.20: modem disappears
> 
> Thanks,
> Jakob

BR,
Nikolaus


[1]: http://projects.goldelico.com/p/gta04-kernel/issues/478/