[systemd-devel] DisplayPort display non-persistent device naming

[Mantas Mikulėnas]

It could be either, but these names are assigned by the kernel – not by
udev.

On Thu, Oct 29, 2020, 22:53 Marcin Kocur <marcin2006 at gmail.com> wrote:

> Hello,
>
> this is the output of turning off and on my display (using power button):
>
>
> [mk at linux ~]$ udevadm  monitor
> monitor will print the received events for:
> UDEV - the event which udev sends out after rule processing
> KERNEL - the kernel uevent
>
> KERNEL[79.909185] change
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0 (drm)
> KERNEL[79.909318] remove
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/i2c-3/i2c-dev/i2c-3 (i2c-dev)
> KERNEL[79.909385] remove
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/i2c-3 (i2c)
> KERNEL[79.909564] remove
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-2/drm_dp_aux1
>
> (drm_dp_aux_dev)
> KERNEL[79.909599] remove
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-2 (drm)
> KERNEL[79.909733] remove
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-3/drm_dp_aux2
>
> (drm_dp_aux_dev)
> KERNEL[79.909756] remove
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-3 (drm)
> KERNEL[79.909882] change
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0 (drm)
> UDEV  [79.912218] remove
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/i2c-3/i2c-dev/i2c-3 (i2c-dev)
> UDEV  [79.912301] change
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0 (drm)
> UDEV  [79.912708] remove
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/i2c-3 (i2c)
> UDEV  [79.913400] remove
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-2/drm_dp_aux1
>
> (drm_dp_aux_dev)
> UDEV  [79.913832] remove
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-3/drm_dp_aux2
>
> (drm_dp_aux_dev)
> UDEV  [79.913875] remove
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-2 (drm)
> UDEV  [79.914230] remove
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-3 (drm)
> UDEV  [79.914814] change
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0 (drm)
> KERNEL[85.337964] add
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/i2c-3/i2c-dev/i2c-3 (i2c-dev)
> KERNEL[85.337996] add
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/i2c-3 (i2c)
> UDEV  [85.340976] add
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/i2c-3/i2c-dev/i2c-3 (i2c-dev)
> UDEV  [85.342384] add
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/i2c-3 (i2c)
> KERNEL[85.482056] add
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-3 (drm)
> KERNEL[85.482116] add
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-3/drm_dp_aux1
>
> (drm_dp_aux_dev)
> KERNEL[85.482215] change
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0 (drm)
> KERNEL[85.482231] add
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-4 (drm)
> KERNEL[85.482308] add
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-4/drm_dp_aux2
>
> (drm_dp_aux_dev)
> KERNEL[85.482386] change
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0 (drm)
> KERNEL[85.482415] change
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0 (drm)
> UDEV  [85.483698] add
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-3 (drm)
> UDEV  [85.485053] add
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-3/drm_dp_aux1
>
> (drm_dp_aux_dev)
> UDEV  [85.486553] change
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0 (drm)
> UDEV  [85.487973] add
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-4 (drm)
> UDEV  [85.489186] add
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0/card0-DP-4/drm_dp_aux2
>
> (drm_dp_aux_dev)
> UDEV  [85.490094] change
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0 (drm)
> UDEV  [85.491090] change
> /devices/pci0000:00/0000:00:08.1/0000:08:00.0/drm/card0 (drm)
>
>
> The monitor was visible in xrandr as DP-2, after power off and on it's
> visible as DP-3 (DP-2 is still there "disconnected").
>
> It's troublesome for:
>
> - GUI display configurators
>
> - scripting
>
> - for Xorg configuration which stops to work:
>
> Section "Monitor"
>      Identifier  "DP-2"
>      Option      "Primary" "true"
> EndSection
>
> Is this a bug or a feature?
>
> --
> Pozdrawiam / Greetings
> Marcin Kocur █
>
> _______________________________________________
> systemd-devel mailing list
> systemd-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/systemd-devel
>
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