When a new USB device is hotplugged, e.g. a USB<->RS232 converter that
exposes a single ttyUSB0, these udev events happen:
add /devices/pci0000:00/0000:00:14.0/usb2/2-1 (usb/usb-device)
add /devices/pci0000:00/0000:00:14.0/usb2/2-1/2-1:1.0 (usb/usb-interface)
add /devices/pci0000:00/0000:00:14.0/usb2/2-1/2-1:1.0/ttyUSB0 (usb-serial)
add /devices/pci0000:00/0000:00:14.0/usb2/2-1/2-1:1.0/ttyUSB0/tty/ttyUSB0 (tty)
bind /devices/pci0000:00/0000:00:14.0/usb2/2-1/2-1:1.0/ttyUSB0 (usb-serial)
bind /devices/pci0000:00/0000:00:14.0/usb2/2-1/2-1:1.0 (usb/usb-interface)
bind /devices/pci0000:00/0000:00:14.0/usb2/2-1 (usb/usb-device)
Our udev rules in MM only added tags in the 'add' events, and it looks
like the only ones 'persistent' after this sequence are those of the
last event happening on the specific path.
This meant that all TTY subsystem rules (e.g. ID_MM_CANDIDATE) would
be stored for later check (e.g. if ModemManager is started after these
rules have been applied), which was ok. "udevadm info -p ..." would
show these tags correctly always.
But this also meant that the 'bind' udev event happening for the USB
device didn't get any of our device-specific tags, and so we would be
missing them (e.g. ID_MM_DEVICE_MANUAL_SCAN_ONLY) if MM is started
after the last event has happened. "udevadm info -p ..." would
not show these tags.
Modify all our rules to also run at the 'bind' events.
See, for context:
https://github.com/systemd/systemd/issues/8221
Commit 7ff57f9808 introduced a change to try to
use ATTRS{bInterfaceNumber} as a common way to match by interface number, but
this logic is broken because all the rules that we use to match by interface
number (attribute in the interface device) also require matching by idVendor
and idProduct (attributes in the physdev device), and udev rules forbid matches
from more than one parent device at a time.
We could use ATTR{bInterfaceNumber} (instead of ATTRS) to tag the actual USB
interface device, but that would require a change in all the plugins to look for
the tag not in the TTY device, but in its parent.
So, recover the original behavior, where a hidden property is created containing
the first bInterfaceNumber found in the list of parent devices, and then run
the matches against idVendor and idProduct only if the hidden property is found
with the expected value.
Rules with a single condition where a parent property is checked with != don't
work properly. E.g.:
SUBSYSTEMS!="usb", GOTO="end"
or:
ATTRS{idVendor}!="abcd", GOTO="end"
Instead, we can mix both those previous parent rules and match them:
SUBSYSTEMS=="usb",ATTRS{idVendor}=="abcd", GOTO="next"
GOTO="end"
LABEL="next"
# Apply rules here
LABEL="end"
In this case both SUBSYSTEMS and ATTRS conditions apply to the parent usb_device
(idVendor attribute is only available in the usb_device), so they apply to all
ports of the same device.
We can just tag the ttys instead of the parent usb device, so that the core
logic which looks in the plugin-specified port tags works properly. There is no
need to explicitly tag the net port, as the probing for this port ends when a
plugin suggestion comes from another port probing on the same device.
This WWAN module came installed in my new HP EliteBook 8570p Laptop.
The patch is generated against the master branch but the same udev
rule should be useful in the 0.5 and 0.6 branches as well.
Signed-off-by: David Härdeman <david@hardeman.nu>
Aleksander Morgado
Fabrice Bellet
Arnd Hannemann
Jens Seidel
Bjørn Mork
Aleksander Morgado
David Härdeman
Dan Williams