How to force which display to be used, even if screen is off?

[jyavenard]

Hi

I have bought an HDMI switch in order to plug more than one HDMI device to my projector.
The PC is connected to one LCD screen over the VGA port ; and a project on the DVI port. I do not use TwinView as I want each screen to be separate.

When my PC boot and the switch isn't on , the screen isn't recognised

Section "Device"
Identifier "Videocard0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce 6500"
Option "TVStandard" "HD720p" #or NTSC etc
Option "UseDisplayDevice" "DFP-0"
Option "FlatPanelProperties" "Scaling = native, Dithering = disabled"
Option "ConnectedMonitor" "DFP,CRT"
Option "ExactModeTimingsDVI" "true"
Option "UseEdidDpi" "DFP-0"
Option "RenderAccel" "True"
Option "UseEvents" "True"
BusID "PCI:1:0:0"
EndSection

Section "Device"
Identifier "Videocard1"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce 6500"
Option "RenderAccel" "True"
Option "UseEvents" "True"
BusID "PCI:1:0:0"
Screen 1
EndSection

Section "Screen"
Identifier "Screen-LCD"
Device "Videocard1"
Monitor "Monitor0"
DefaultDepth 24
Option "TwinView" "0"
# Option "metamodes" "CRT: 1280x1024 +0+0"
EndSection

Section "Screen"
Identifier "Screen-Projector"
Device "Videocard0"
Monitor "Projector"
DefaultDepth 24
Option "TwinView" "0"
Option "ModeValidation" "NoDFPNativeResolutionCheck"
Option "metamodes" "DFP: 1280x720 +0+0"
EndSection

If I remove the last line:
Option "metamodes" "DFP: 1280x720 +0+0"

The even if the HDMI switch is on, it will be recognised but only in 640x480.
I'd have to restart X for the resolution to be correct.

With "Option "metamodes" "DFP: 1280x720 +0+0""
Comparing the two logs between one boot with the HDMI switch on and one with the HDMI switch off:

> (WW) NVIDIA(GPU-0): Unable to read EDID for display device DFP-0
410c411
< (--) NVIDIA(0): Panasonic AE-900 (DFP-0)
---
> (--) NVIDIA(0): DFP-0
412,414c413,415
< (--) NVIDIA(0): Panasonic AE-900 (DFP-0): 155.0 MHz maximum pixel clock
< (--) NVIDIA(0): Panasonic AE-900 (DFP-0): Internal Single Link TMDS
< (II) NVIDIA(0): Mode Validation Overrides for Panasonic AE-900 (DFP-0):
---
> (--) NVIDIA(0): DFP-0: 155.0 MHz maximum pixel clock
> (--) NVIDIA(0): DFP-0: Internal Single Link TMDS
> (II) NVIDIA(0): Mode Validation Overrides for DFP-0:
420,422c421,422
< (WW) NVIDIA(0): Panasonic AE-900 (DFP-0)'s EDID does not contain a maximum
< (WW) NVIDIA(0): image size; cannot compute DPI from Panasonic AE-900
< (WW) NVIDIA(0): (DFP-0)'s EDID.
---
> (WW) NVIDIA(0): Unable to get display device DFP-0's EDID; cannot compute DPI
> (WW) NVIDIA(0): from DFP-0's EDID.
443c443
< (--) NVIDIA(1): Panasonic AE-900 (DFP-0)
---
> (--) NVIDIA(1): DFP-0
445,446c445,446
< (--) NVIDIA(1): Panasonic AE-900 (DFP-0): 155.0 MHz maximum pixel clock
< (--) NVIDIA(1): Panasonic AE-900 (DFP-0): Internal Single Link TMDS
---
> (--) NVIDIA(1): DFP-0: 155.0 MHz maximum pixel clock
> (--) NVIDIA(1): DFP-0: Internal Single Link TMDS

I think I have followed all the steps to force that the screen is recognised ; it even shows up in the log, but it's not active

Any ideas what I have been missing?

Thank you
Jean-Yves

[netllama]

The best way to make this work is to capture the EDID from the external display, and then specify it with the CustomEDID option, along with the ConnectedMonitor option. See the driver README for more information, and post an nvidia-bug-report.log if you have further questions.

[jyavenard]

Originally Posted by netllama

The best way to make this work is to capture the EDID from the external display, and then specify it with the CustomEDID option, along with the ConnectedMonitor option. See the driver README for more information, and post an nvidia-bug-report.log if you have further questions.

This is what I thought of doing, however, I haven't managed to find a way to retrieve the EDID of the screen.

Is this in the README ?

Also, interestingly, with the newer nvidia kernel, for the 1st x11 adapter, I have to specify:
ConnectedMonitor DFP,CRT ; even though I am not using TwinView
if I want something displayed on the VGA screen. I didn't have to do that before.
Each adapter had its own ConnectedMonitor option
Thank you
Jean-Yves

[netllama]

You acquire the EDID by starting X while the display device is connected and powered on.

I'm not really clear on the other problem you're describing as ConnectedMonitor has no connection to Twinview.

[jyavenard]

Originally Posted by netllama

You acquire the EDID by starting X while the display device is connected and powered on.

Yes, I found in one of our previous post, how to use nvidia-settings to extract the EDID

I'm not really clear on the other problem you're describing as ConnectedMonitor has no connection to Twinview.

I seem to have misread the README file, there as a mention that if you were to use Twinview, you would have to specify both monitors in ConnectedMonitor with ConnectedMonitor DFP,CRT.
I can't find that text anymore.

What I was trying to say is that prior to upgrading to 100.14.x ; I only had to put ConnectedMonitor DFP in the DFP device section, now I must put ConnectedMonitor DFP,CRT to get something on the CRT.

In any case, thank you, you're the man.

It is now working perfectly as I wanted to . When I turn the projector on, I now get a beautiful picture ...

Thank you again
Jean-Yves