Re: Unsalble cellular connection

[Jonas Bonn <jonas@norrbonn.se>]

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On 19/08/2019 09:50, Jonas Bonn wrote:
> 
> 
> On 19/08/2019 09:36, Michael Nazzareno Trimarchi wrote:
>> Hi
>>
>> On Mon, Aug 19, 2019 at 7:38 AM Jonas Bonn <jonas@norrbonn.se> wrote:
>>> The kernel log has this:
>>>
>>> Aug 17 08:51:46 solar kernel: usb 1-1: USB disconnect, device number 3
>>> Aug 17 08:51:46 solar kernel: option1 ttyUSB0: GSM modem (1-port)
>>> converter now disconnected from ttyUSB0
>>> Aug 17 08:51:46 solar kernel: option 1-1:1.0: device disconnected
>>> Aug 17 08:51:46 solar kernel: option1 ttyUSB1: GSM modem (1-port)
>>> converter now disconnected from ttyUSB1
>>> Aug 17 08:51:46 solar kernel: option 1-1:1.2: device disconnected
>>> Aug 17 08:51:46 solar kernel: qmi_wwan 1-1:1.3: nonzero urb status
>>> received: -71
>>>
>>> That's a USB communication failure!
>>>
>>> Aug 17 08:51:46 solar kernel: qmi_wwan 1-1:1.3: wdm_int_callback - 0 
>>> bytes
>>> Aug 17 08:51:46 solar kernel: qmi_wwan 1-1:1.3: wdm_int_callback -
>>> usb_submit_urb failed with result -19
>>> Aug 17 08:51:46 solar kernel: qmi_wwan 1-1:1.3 wwan0: unregister
>>> 'qmi_wwan' usb-ci_hdrc.1-1, WWAN/QMI device
>>>
>>> Below, the device (modem) is reenumerated, which would indicate to me
>>> that it has restarted.  I don't think the kernel automatically sends a
>>> reset to a device on comm failures...???  This explains the
>>> communication failure, at least.
>>
>> Can be chattering and rush current? Even are you sure that you don't have
>> some reset our of the ofono service that send an at command that
>> restart the modem?
> 
> Just to try to prevent us from going down the wrong rabbit hole here:
> i)  The modem is a QMI device so there are no AT commands being sent
> ii)  The ofono log should show any such command if it were being 
> transmitted (unfortunately, JH hasn't been able to produce a proper log 
> around this event, yet)
> iii)  I'm pretty certain that the QMI (gobi) driver in ofono doesn't 
> support any 'reset' command
> 
> My inclination would be to look elsewhere.
> 
> i)  figure out what reset signalling the modem does and put a scope on it.
> ii)  try to eliminate ofono and connman from the picture entirely by 
> running the modem manually... what's the utility called, qmictl?  comes 
> with libqmi, in any case.  Presumably, if it's a hardware issue, the 
> problem will show itself under these circumstances, as well.
> 

Is the problem reproducible with the EVK?  If not, you've pretty much 
eliminated software as the cause of the issue... it's the same device, 
but with an independent power supply.

/Jonas