On 17.07.24 13:10, Florian Eckert wrote:
Hello Dev´s,
I hope someone can help me here. I have noticed since the
kernel update in the master branch of OpenWrt to 6.6 that
the enumeration of the USB host controllers is suddenly
randomly.
This has been encountered on the APU3 board from PCengine[1].
That wasn't the case with the 5.15 kernel before, or I didn't
notice it. I also don't know if it must have fixed paths
so that the USB host controllers always have the same path.
Boot1
lrwxrwxrwx 1 root root 0 Jul 17 12:43 usb1 ->
../../../devices/pci0000:00/0000:00:13.0/usb1
lrwxrwxrwx 1 root root 0 Jul 17 12:43 usb2 ->
../../../devices/pci0000:00/0000:00:12.0/usb2
lrwxrwxrwx 1 root root 0 Jul 17 12:43 usb3 ->
../../../devices/pci0000:00/0000:00:10.0/usb3
lrwxrwxrwx 1 root root 0 Jul 17 12:43 usb4 ->
../../../devices/pci0000:00/0000:00:10.0/usb4
Boot2
lrwxrwxrwx 1 root root 0 Jul 17 12:56 usb1 ->
../../../devices/pci0000:00/0000:00:12.0/usb1
lrwxrwxrwx 1 root root 0 Jul 17 12:56 usb2 ->
../../../devices/pci0000:00/0000:00:13.0/usb2
lrwxrwxrwx 1 root root 0 Jul 17 12:56 usb3 ->
../../../devices/pci0000:00/0000:00:10.0/usb3
lrwxrwxrwx 1 root root 0 Jul 17 12:56 usb4 ->
../../../devices/pci0000:00/0000:00:10.0/usb4
As you can see the usb1 and usb2 are swapped!
The problem now is that the ModemManager is using the syspath
to reference the modem in the uci configuration [2]. If the modem's
syspath is now random, the system can no longer find the modem and
cannot establish a connection.
1. Does anyone have the same problem?
2. Is the path of usb<x> randomly intentional?
3. Can I somehow force the path across a restart?
I think the most likely cause is more parallelization in device probe in
order to speed up boot time. Not sure if there is a way to make it
deterministic, but even if there is, it might still change across kernel
upgrades.
In my opinion, the best course of action is to just deal with it by
changing the code to no longer rely on usbX names. Better make it depend
on the sysfs path, similar to wifi-device path handling in the wireless
config.
- Felix
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