Created attachment 301600 [details] dmesg I have A PC with Radeon RX480 which has HDMI output connected to HDMI input on Marantz SR5015 AV reciever and there the HDMI output goes to a TV (Panasonic TX-55CX200E). The DVI output is connected to an LCD monitor. The AVR has the feature to pass through HDMI signal when put into standby mode. When I switch AVR from/to standby mode it looks like it for a very short time interrupts the connection from PC to TV and during this time it appears that the video card output turns off and monitor layout is re-aranged to one screen (DVI) only and then almost immediately back two previous dual screen layout. Would it be possible to delay turning off the HDMI output for a bit longer so that it would wait long enough that AVR would reconnect entire HDMI path to TV back again and the HDMI output on video card would not need to be turned off and keep sending output in the meantime? So that the display layout configuration would keep being in dual-screen mode for the whole time?
Created attachment 301601 [details] Xorg.0.log
Created attachment 301602 [details] lspci
I suspect the receiver toggles the hotplug pin when it switches to/from passthrough mode notify the GPU that the EDID will change (e.g., from receiver audio to monitor audio) otherwise the GPU won't know that the receiver is no longer part of the chain. The driver doesn't actually do anything when it receives this hotplug interrupt. It just tells userspace. Your desktop environment listens for hotplug events and then acts on them (either enabling or disabling displays). Your best bet is probably to change the behavior of your desktop environment when it receives a hotplug notification. Alternatively, you could try and block drm hotplug events in udev.
If I got it right, the hotplug events are all posted via udev? If so, is it correct to use "udevadm monitor --environment --udev" to see these events posted to userspace? Or is there somethign better? Just trying to make the best sense out of it to try making a workaround and gather as much relevant information to report a good bug/feature request with correct info to KDE developers. If I use "udevadm monitor --environment --udev" I get the output: udevadm monitor --environment --udev monitor will print the received events for: UDEV - the event which udev sends out after rule processing < switching AVR from on to standby mode > UDEV [35121.304457] change /devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0 (drm) ACTION=change DEVPATH=/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0 SUBSYSTEM=drm HOTPLUG=1 CONNECTOR=74 DEVNAME=/dev/dri/card0 DEVTYPE=drm_minor SEQNUM=12043 USEC_INITIALIZED=4651406 ID_PATH=pci-0000:01:00.0 ID_PATH_TAG=pci-0000_01_00_0 ID_FOR_SEAT=drm-pci-0000_01_00_0 MAJOR=226 MINOR=0 DEVLINKS=/dev/dri/by-path/pci-0000:01:00.0-card TAGS=:uaccess:master-of-seat:seat: CURRENT_TAGS=:uaccess:master-of-seat:seat: UDEV [35124.216717] change /devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0 (drm) ACTION=change DEVPATH=/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0 SUBSYSTEM=drm HOTPLUG=1 CONNECTOR=74 DEVNAME=/dev/dri/card0 DEVTYPE=drm_minor SEQNUM=12044 USEC_INITIALIZED=4651406 ID_PATH=pci-0000:01:00.0 ID_PATH_TAG=pci-0000_01_00_0 ID_FOR_SEAT=drm-pci-0000_01_00_0 MAJOR=226 MINOR=0 DEVLINKS=/dev/dri/by-path/pci-0000:01:00.0-card TAGS=:uaccess:master-of-seat:seat: CURRENT_TAGS=:uaccess:master-of-seat:seat: < switching AVR from standby to on mode > UDEV [35155.373681] change /devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0 (drm) ACTION=change DEVPATH=/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0 SUBSYSTEM=drm HOTPLUG=1 CONNECTOR=74 DEVNAME=/dev/dri/card0 DEVTYPE=drm_minor SEQNUM=12048 USEC_INITIALIZED=4651406 ID_PATH=pci-0000:01:00.0 ID_PATH_TAG=pci-0000_01_00_0 ID_FOR_SEAT=drm-pci-0000_01_00_0 MAJOR=226 MINOR=0 DEVLINKS=/dev/dri/by-path/pci-0000:01:00.0-card TAGS=:uaccess:master-of-seat:seat: CURRENT_TAGS=:uaccess:master-of-seat:seat: UDEV [35158.196252] change /devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0 (drm) ACTION=change DEVPATH=/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0 SUBSYSTEM=drm HOTPLUG=1 CONNECTOR=74 DEVNAME=/dev/dri/card0 DEVTYPE=drm_minor SEQNUM=12049 USEC_INITIALIZED=4651406 ID_PATH=pci-0000:01:00.0 ID_PATH_TAG=pci-0000_01_00_0 ID_FOR_SEAT=drm-pci-0000_01_00_0 MAJOR=226 MINOR=0 DEVLINKS=/dev/dri/by-path/pci-0000:01:00.0-card TAGS=:uaccess:master-of-seat:seat: CURRENT_TAGS=:uaccess:master-of-seat:seat: UDEV [35158.953569] change /devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0 (drm) ACTION=change DEVPATH=/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0 SUBSYSTEM=drm HOTPLUG=1 CONNECTOR=74 DEVNAME=/dev/dri/card0 DEVTYPE=drm_minor SEQNUM=12050 USEC_INITIALIZED=4651406 ID_PATH=pci-0000:01:00.0 ID_PATH_TAG=pci-0000_01_00_0 ID_FOR_SEAT=drm-pci-0000_01_00_0 MAJOR=226 MINOR=0 DEVLINKS=/dev/dri/by-path/pci-0000:01:00.0-card TAGS=:uaccess:master-of-seat:seat: CURRENT_TAGS=:uaccess:master-of-seat:seat: UDEV [35161.036327] change /devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0 (drm) ACTION=change DEVPATH=/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0 SUBSYSTEM=drm HOTPLUG=1 CONNECTOR=74 DEVNAME=/dev/dri/card0 DEVTYPE=drm_minor SEQNUM=12051 USEC_INITIALIZED=4651406 ID_PATH=pci-0000:01:00.0 ID_PATH_TAG=pci-0000_01_00_0 ID_FOR_SEAT=drm-pci-0000_01_00_0 MAJOR=226 MINOR=0 DEVLINKS=/dev/dri/by-path/pci-0000:01:00.0-card TAGS=:uaccess:master-of-seat:seat: CURRENT_TAGS=:uaccess:master-of-seat:seat:
Yes, those are the events. The desktop environment listens for them and reacts.