Re: Alcatel X200 troubleshooting

[Dan Williams <dcbw redhat com>]

On Thu, 2011-04-21 at 20:57 +0200, Javier Almasoft wrote:
> 2011/4/21, Dan Williams <dcbw redhat com>:
> > Normally we don't want to blacklist specific ports as sometimes
> > manufacturers (like Huawei and others) use the same USB ID for multiple
> > devices and the ports used on those might be different.  For other
> > devices (Sierra, Novatel, etc) AT commands can be used to change port
> > assignments around and thus you really don't know which port is the
> > secondary AT port and which is the GPS port based on hardcoded numbers.
> >
> Well, my intention was not only to solve my specific issue, but to be
> configurable to other similar devices without having to modify the
> source code, i.e., being able to adapt to different implementations of
> port assignments, either on the same specific model, either on
> different models with the same IDs (or different but with similar
> problems of timeout), by adapting only udev rules. Indeed, on this
> same combination of computer/adapter, I had also a usb serial adapter
> (PL-2303, 067b:2303) that got unusable because of ModemManager (the
> serial printer attached failed to print after being tested), and
> strangely the value ID_MM_DEVICE_IGNORE was 'ignored' by the generic
> plugin. Thankfully my ID_MM_PORT_IGNORE was there for the rescue
> ;-)...
> 
> In other words, if you need to blacklist a different port list in your
> adapter, just rewrite the rules. Also, you can produce a snappier
> response in case you have 'dead' ports, even if your adapter is
> recognized normally (assuming the port assignment remains static on
> 'your' device).
> 
> > But in this case, if you're sure neither of these apply, we could
> > potentially blacklist those ports.  The only way of doing this is to use
> > the USB interface # since that stays constant, while port device names
> > (ie ttyUSBx or ttyACMx) do not.
> 
> >
> > Some devices already do this, like the x22x driver.  Any port that's not
> > explicitly tagged with ID_MM_X22X_TAGGED gets ignored.
> >
> > Dan
> >
> >
> 
> Of course I was referring not to ttyUSB# names to mark dead ports, but
> to USB interface numbers, that's why I use the ENV .MM_USBIFNUM (which
> ultimately comes from $attr{bInterfaceNumber}) as one of the
> conditions in the rule. In my case, due to having another usb to
> serial adapter, I was never sure which would be assigned first, so
> using device names was never considered (there were sometimes also
> 'zombie' ttyUSB devices, maybe because they were in use when I
> unplugged the GSM stick).
> 
> I don't think that hardcoding the unusable ports in the driver would
> be a better idea.

No, it's usually not, but all the black/whitelist stuff in MM is
currently done using udev rules for exactly this reason.

Dan