From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tony Lindgren <tony@atomide.com>
Subject: Re: [PATCH 1/2] tty: n_gsm: Fix long delays with control frame
 timeouts in ADM mode
Date: Mon, 9 Apr 2018 06:42:59 -0700
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To: Pavel Machek <pavel@ucw.cz>
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* Pavel Machek <pavel@ucw.cz> [180409 10:56]:
> Ok, I should have all that enabled. But droid4-ngsm still fails:
> 
> user@devuan:/my/droid4-ngsm$ sudo ./droid4-ngsm
> Starting ngsm..
> Testing ngsm..
> Could not open /dev/gsmtty1: Level 2 halted
> Trying to start ngsm again: Level 2 halted
> Starting ngsm..

I guess you must have phy-mapphone-mdm6600 enabled as you a have
working modem over USB. What do you see in dmesg if you enable n_gsm
debug with modprobe n_gsm debug=0xff or on kernel cmdline?

> commit 984c7706ff180e33096c57183435d925cb644576 says:
> 
>     ARM: dts: omap4-droid4: Configure uart1 pins
> 
>     These are needed to use the n_gsm driver for TS 27.010 UART
>         multiplexing. Note that support for the OOB wake gpio is still
> 	    missing so the UART is not yet usable for n_gsm.
> 
> ...am I still missing the OOB wake gpio support?

We can get away without OOB wake gpio for a while as mdm6600 is not
yet suspended over USB. But if you have manually suspended mdm6600
USB interface via /sys, then it won't respond properly on n_gsm
either.

Regards,

Tony