Re: [PATCH 1/6] tty: n_gsm: Add support for serdev drivers

Jiri Slaby
2024-12-19T07:53:50Z

On 19. 12. 24, 8:45, Ivaylo Dimitrov wrote:
> Hi,
>
> ...
>
> On 29.11.20 г. 22:51 ч., Pavel Machek wrote:
>>>
>>> It looks like you may also have a problem with tty hangups, which serdev
>>> does not support currently. There are multiple paths in n_gsm which can
>>> trigger a hangup (e.g. based on remote input) and would likely lead to a
>>> crash
>>
>> I don't believe we need to support hangups for the Droid 4, but
>> obviously it would be good not to crash. But I don't know where to
>> start looking, do you have any hints?
>>
>
> I changed the patch so it calls tty_port_register_device_serdev, ported
> gnss driver to use serdev_device, got it working:
>
> root@devuan-droid4:~# cat /dev/gnss0
> $GPGGA,,,,,,0,,,,,,,,*66
> $GNGNS,,,,,,NN,,,,,,*53
> $GNGNS,,,,,,NN,,,,,,*53
> $GNGNS,,,,,,NN,,,,,,*53
> $GPVTG,,T,,M,,N,,K,N*2C
> $GPRMC,,V,,,,,,,,,,N*53
> $GPGSA,A,1,,,,,,,,,,,,,,,*1E
> $GLGSV,1,1,01,255,,,37*52
> $GPGGA,,,,,,0,,,,,,,,*66
> $GNGNS,,,,,,NN,,,,,,*53
> $GNGNS,,,,,,NN,,,,,,*53
> $GNGNS,,,,,,NN,,,,,,*53
>
> However, I get:
>
> gsmtty gsmtty4: tty_hangup: tty->count(1) != (#fd's(0) + #kopen's(0))
>
> when closing /dev/gnss0
>
> Any hint what shall be implemented in serdev to properly handle hangups?

Without code, no.

> Or, shall I ignore that warning?

Definitely not.

thanks,
--
js
suse labs