Re: Using USB serial device with a cdc-acm driver
On Dec 2, 2014, at 1:42 AM, Bob Proulx <bob@proulx.com> wrote:
> Dmitriy Fitisov wrote:
>> USB descriptors configured as a modem, so, when I connect it to Linux, cdc-acm module is loaded.
>> However, there is apparently some process which is watching modems, so on connection
>> I got some info on my device - on Ubuntu it is AT commands, for which I have adapted firmware
>> (seems ModemManager is running), but on Raspberry I cannot find out what process attaches
>> to my "modem" and what it wants.
>> It sends a data similar to terminal control sequence.
>
> Possibly 'getty'?
>
May be. In this case I have to have some line in inittab which tells me that getty has to be activated on /dev/ttyACM0,
but I do not have it. Somewhere else?
>> Where should I look at? I want to turn this process off.
>
> Look in /var/log/syslog and hopefully something will be logged there.
No, nothing related.
I compiled cdc-acm with debug support and print bytes flowing and see that there is some info exchange
with lot of 0x20 0x08 sequences after some "term control sequences"
>
> Look in 'ps -ef' and see if anything is shown associated with the tty
> device.
Tried that. No such things. It is "come and go".
I carefully went through list of running processes with "top" and identified couple of suspects, which behaves
actively at the time of insertion: udevd and ifplugd. If I stop service udevd, no devices created in
/dev/ which is logically, udevd should be responsible for some part.
>
> Bob
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