MMKernelDevice ID_USB_INTERFACE_NUM property isn't set anymore

[Dan Williams]

On Wed, 2017-05-03 at 14:55 +0200, Aleksander Morgado wrote:
> On Wed, May 3, 2017 at 2:09 PM, Carlo Lobrano <c.lobrano at gmail.com>
> wrote:
> > > > > When using the "udev" backend, which you are, the property
> > > > > isn't
> > > > > "loaded" or "stored" anywhere in our code. We directly look
> > > > > for the
> > > > > property in the GUdevDevice underneath.
> > > > > 
> > > > > Could you run udevadm info in the port to see if
> > > > > ID_USB_INTERFACE_NUM
> > > > > is
> > > > > set?
> > > > 
> > > > Oh, I see now.
> > > > The property is actually unset. Is there anything else I can do
> > > > to have
> > > > this
> > > > information?
> > > > 
> > > > $ udevadm info /dev/ttyACM0
> > > > P:
> > > > 
> > > > /devices/pci0000:00/0000:00:14.0/usb3/3-3/3-3.2/3-3.2.4/3-
> > > > 3.2.4.3/3-3.2.4.3:1.0/tty/ttyACM0
> > > > N: ttyACM0
> > > > E: DEVNAME=/dev/ttyACM0
> > > > E:
> > > > 
> > > > DEVPATH=/devices/pci0000:00/0000:00:14.0/usb3/3-3/3-3.2/3-
> > > > 3.2.4/3-3.2.4.3/3-3.2.4.3:1.0/tty/ttyACM0
> > > > E: ID_MM_CANDIDATE=1
> > > > E: ID_MM_TELIT_PORTS_TAGGED=1
> > > > E: ID_MM_TELIT_TAGGED=1
> > > > E: MAJOR=166
> > > > E: MINOR=0
> > > > E: SUBSYSTEM=tty
> > > > E: TAGS=:systemd:
> > > > E: USEC_INITIALIZED=75726372964
> > > 
> > > Do you have a /lib/udev/rules.d/60-serial.rules in your system
> > > that
> > > sets ID_USB_INTERFACE_NUM? Maybe we shouldn't rely on having
> > > that?
> > > 
> > 
> > No, I do not have that 60-serial.rules file, but I did obtained the
> > result I
> > wanted adding the following rule to 77-mm-telit-port-types.rules
> > 
> > SUBSYSTEMS=="usb", ATTRS{bInterfaceNumber}=="?*",
> > ENV{ID_USB_INTERFACE_NUM}="$attr{bInterfaceNumber}"
> 
> We need to fix this; we shouldn't be relying on a systemd property. I
> originally thought this was provided by udev itself... although with
> the systemd/udev development being done together, it may actually be
> a
> packaging decision; no idea.

I think it originally was a udev property.  And I see it's still
provided by systemd-udev, so I'd expect it to be present if udev is
installed...

Dan

> One option would be to define ID_MM_USB_INTERFACE_NUM in all plugin
> udev rules (telit, option, huawei, cinterion), and update the plugins
> source code to use the new ID_MM_ prefixed property.
> 
> Another option would be to provide a common rules file that is run
> before all the others and defines ID_MM_USB_INTERFACE_NUM for all
> plugins... we could have a 77-mm-serial.rules file and rename all
> plugin rules to 78-mm-...
> 
> What do you think?
>