Re: Re-scanning for available devices/connections after failure

[Daenyth Blank <daenyth gmail com>]

On Thu, Jul 22, 2010 at 17:34, Daenyth Blank <daenyth gmail com> wrote:
> On Thu, Jul 22, 2010 at 19:20, Dan Williams <dcbw redhat com> wrote:
>> That is, well, unfortunate...  Sierra firmware is usually top-notch so
>> I'd consider firmware crashes to be less of an issue here than with say
>> Huawei or ZTE devices.  But they still could be an issue.  If there's
>> any way we can get logs from the devices at all, that would be
>> excellent.
>>
>> But as a workaround, you could use a watchdog that sends a USB reset to
>> the device if it isn't seen in ModemManager for more than 30 seconds.
>> There are some Python examples that list modems here:
>>
>> http://cgit.freedesktop.org/ModemManager/ModemManager/tree/test/list-modems.py
>>
>> and that coupled with echoing some stuff to sysfs might be enough to
>> shoot the modem in the head and get it to re-enumerate.
>>
>> If there's *any* way we can get 'dmesg' or /var/log/messages from the
>> system when this happens that would help a lot.
>>
>> Dan
> Right now I have a watchdog that restarts NM or reboots if it fails a
> few times. I'll see what I can put together with the usb reset. I
> thought such a thing might be possible but I didn't find anything. I
> tried using /sys/bus/usb/.../power, but it didn't seem to do anything.
> I'll see if I can have the watchdog also take a snapshot of the
> logfiles and then I can pull them when it comes back up.
>

I had a chance to look over the code example you sent, but I'm not
sure what you mean by "usb reset". Can you clarify that?