[Letux-kernel] wwan logic inversion

[H. Nikolaus Schaller]

Hi Andreas,

> Am 24.11.2018 um 12:17 schrieb Andreas Kemnade <andreas at kemnade.info>:
> 
> Hi Nikolaus,
> 
> On Sat, 24 Nov 2018 09:29:38 +0100
> "H. Nikolaus Schaller" <hns at goldelico.com> wrote:
> 
>> 
>> Here it seems to query the modem status pin (gpio value = 0/1).
>> 
>> Hope this helps to find out what is really going on.
>> 
> well, modem was in bad initial state

ah, I see. How did it come into that state? Can we/do we need to protect against it?
The only sequence I am aware of:

1. boot
2. rfkill unblock wwan
3. warm reset by external hardware (not a sudo reboot because there can be a rfkill block in init.d/systemd shutdown config)
4. boots again and assumes modem is off

Since the GTA04 has no external warm reset and the PLS8 in the Pyra can't be turned off by a second impulse, neither
can get into a permanently inverted state.

At least by theory...

> and without feedback line, it
> cannot be corrected.

Well, it could if we find a way to make use of the phy phandle
and query the phy state...

Anyways it has revealed that the DT node for the feedback gpio got lost :)

BR and thanks,
Nikolaus