Projector HDMI switching causes X to fail

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FishingRod001
Posts: 3
Joined: 2019/07/15 12:35:59

Projector HDMI switching causes X to fail

Post by FishingRod001 » 2019/07/15 13:25:24

G'Day to All,

I've been searching everywhere, for days...so here is the scenario:

Centos 7 with a projector and a HDMI switch to project various devices. If the HDMI switch is on another device when Centos 7 boots the X session fails.
A reboot fixes this, provided the HDMI switch is set to the PC.
I've attempted to 'trick' the /etc/X11/xorg.conf file with options to ignore EDID and manually set the resolution etc, to no avail.

Another reason why this is useful: running the Centos 7 PC via VNC, it is somewhat frustrating to fire up the projector so Xorg (X11?) is happy, then turn it off to run various apps via a laptop when a big screen is not required...or when going offsite.

Please, I do not want to run a Xvnc, I just wish to avoid having to turn on the proj to enable a remote session, a remote session that when/if I need the projector....turn it on and there is the PC. I did this once on a Raspberry Pi running Wheezy...and that too was a saga... :( then I upgraded to Jessie and of course...it no longer allows a remote session despite the fact it can boot into it's graphical session with it's monitor turned off...sigh!!

Note to self: TAKE NOTES!!!

A portion of the /var/log/Xorg.0.log

==================================================================================================================
[ 60.826] (==) NVIDIA(0): No modes were requested; the default mode "nvidia-auto-select"
[ 60.826] (==) NVIDIA(0): will be used as the requested mode.
[ 60.826] (==) NVIDIA(0):
[ 60.826] (--) NVIDIA(0): No enabled display devices found; starting anyway because
[ 60.826] (--) NVIDIA(0): AllowEmptyInitialConfiguration is enabled
[ 60.826] (II) NVIDIA(0): Validated MetaModes:
[ 60.826] (II) NVIDIA(0): "NULL"
[ 60.826] (II) NVIDIA(0): Virtual screen size determined to be 640 x 480
[ 60.826] (==) NVIDIA(0): DPI set to (75, 75); computed from built-in default
[ 60.826] (II) NVIDIA: Using 6144.00 MB of virtual memory for indirect memory
[ 60.826] (II) NVIDIA: access.
[ 60.829] (II) NVIDIA(0): ACPI: failed to connect to the ACPI event daemon; the daemon
[ 60.829] (II) NVIDIA(0): may not be running or the "AcpidSocketPath" X
[ 60.829] (II) NVIDIA(0): configuration option may not be set correctly. When the
[ 60.829] (II) NVIDIA(0): ACPI event daemon is available, the NVIDIA X driver will
[ 60.829] (II) NVIDIA(0): try to use it to receive ACPI event notifications. For
[ 60.829] (II) NVIDIA(0): details, please see the "ConnectToAcpid" and
[ 60.829] (II) NVIDIA(0): "AcpidSocketPath" X configuration options in Appendix B: X
[ 60.829] (II) NVIDIA(0): Config Options in the README.
[ 60.847] (II) NVIDIA(0): Setting mode "NULL"
[ 60.874] (==) NVIDIA(0): Disabling shared memory pixmaps
[ 60.874] (==) NVIDIA(0): Backing store enabled
[ 60.874] (==) NVIDIA(0): Silken mouse enabled
[ 60.874] (==) NVIDIA(0): DPMS enabled
[ 60.874] (WW) NVIDIA(0): Option "IgnoreEDID" is not used
[ 60.874] (II) Loading sub module "dri2"
[ 60.874] (II) LoadModule: "dri2"
[ 60.874] (II) Module "dri2" already built-in
[ 60.874] (II) NVIDIA(0): [DRI2] Setup complete
[ 60.874] (II) NVIDIA(0): [DRI2] VDPAU driver: nvidia
====================================================================================================================

The /etc/X11/xorg.conf file:

====================================================================================================================
Section "Monitor"
Identifier "Epson"
HorizSync 28.0-80.0
VertRefresh 48.0-75.0
Modeline "1920x1080_100.00" 302.02 1920 2072 2280 2640 1080 1081 1084 1144
Option "IgnoreEDID" "True"
Option "UseEDIDFreqs" "FALSE"
Option "UseEDIDDpi" "FALSE"
EndSection

Section "Device"
Identifier "Videocard0"
Driver "nvidia"
Option "AllowEmptyInitialConfiguration" "true"

EndSection

Section "Screen"
Identifier "OFF_Epson"
Device "Videocard0"
Monitor "Epson"
SubSection "Display"
EndSubSection
EndSection
=====================================================================================================================

Despite the /var/log/Xorg.0.log looking promising:

[root@ent ~]# xrandr
Can't open display

I'm hoping that there are computer users out there whom would appreciate walking past a PC, pressing the power button (the monitor is turned off) then by the time it has booted (auto login) I can sit outside with a cold one and laptop into it just as if I was in front of the monitor in a work position with the same desktop ...etc etc. In the good 'ol days before EDID it was easy!! ;)

Thanks for reading and cheers for now, Rod. :)

... --- ...

lightman47
Posts: 1521
Joined: 2014/05/21 20:16:00
Location: Central New York, USA

Re: Projector HDMI switching causes X to fail

Post by lightman47 » 2019/07/15 15:26:49

At any given time I have 3 or more headless machines (no mouse, keyboard, monitor) that boot just fine without me editing anything and to which I ssh in. Any chance there's some relevant BIOS setting that's expecting a video connection?

chemal
Posts: 776
Joined: 2013/12/08 19:44:49

Re: Projector HDMI switching causes X to fail

Post by chemal » 2019/07/15 18:33:24

Try xorg.conf options "ConnectedMonitor" and "CustomEDID". Something like

Code: Select all

Section "Device"
   ...
   Option "ConnectedMonitor" "DFP-0"
   Option "CustomEDID" "DFP-0:/etc/X11/edid.bin"
   ...
EndSection
Starting with a working X session, the proper name for the connector can be found in /var/log/Xorg.0.log. Nvidia-settings offers to dump EDID data to a file on the monitor tab.

See also https://access.redhat.com/solutions/54937. Ignore the dual-head part.

FishingRod001
Posts: 3
Joined: 2019/07/15 12:35:59

Re: Projector HDMI switching causes X to fail

Post by FishingRod001 » 2019/07/18 12:30:16

Thank you Chemal, you nailed it!!

CustomEDID :)

Much appreciated...much DuckDuckGo searching with no answers pointed me towards this forum, and for the first time ever...I posted the problem that was answered by you accurately.

Brilliant!!!

Have a great weekend, regards, Rod.

FishingRod001
Posts: 3
Joined: 2019/07/15 12:35:59

Re: Projector HDMI switching causes X to fail

Post by FishingRod001 » 2019/07/18 12:34:43

Thanks for your reply Lightman47!!

If only SSH and a bash shell were required the headless PC would be easy...but in this case a GUI is necessary and Chemal's

xorg.conf

"ConnectedMonitor"

and

"CustomEDID"

options did the job!! All the best, regards, Rod.

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