HDMI to DVI cable not working for second monitor

Acer

#1

I am a Blender3D student and really need my second monitor to function for tutorials and additional workspace :slight_smile:

I have an AMD RX 560 and finally got running amdgpu-pro drivers working correctly.

I’m trying to utilize my main workstations GPU HDMI port to a second DVI monitor. No display at all in the OS, but it does display in BIOS and Ubuntu boot screen.

some info on my system:

X Server 1.19.6

modinfo amdgpu | grep version
version:        18.50.1.418
srcversion:     533BB7E5866E52F63B9ACCB

OpenGL vendor string: Advanced Micro Devices, Inc.
OpenGL renderer string: Radeon RX 560 Series
OpenGL core profile version string: 4.6.13542 Core Profile Context 18.50.1.418
Vulkan version 1.1.73

My main display is an Acer DVI monitor. I have confirmed that dual display works fine in my DE with a small KUMAN 7" HDMI touch display I use for my Raspberry Pi project but I cannot get a second monitor to display using an HDMI to DVI cable. I know the cable is good because it works with my Pi’s and my kid’s Linux Mint machine (it has an Nvidia GPU with only HDMI output).

Is this a known issue? Is there a work around?

Thanks for your time.


#2

Should work.

Look through /var/log/Xorg.0.log to see if the second monitor is detected by the RX560 and the linux drivers. You should see a line that says “EDID for output DVI-0” and a line with “EDID for output HDMI-0”. The next line after the EDID line should be you monitors model info. There are lines for your monitors capabilities, etc.

You can also look through the same log file on you PIs and the Linux mint machine to see what the monitor should be sending.

djb


#3

Here is some output of my MATE /var/log/Xorg.0.log

Everything with EDID is includes:
(II) AMDGPU(0): EDID vendor “ACR”, prod id 94

...
[    10.567] (II) AMDGPU(0): Output DisplayPort-0 has no monitor section
[    10.567] (II) AMDGPU(0): Output HDMI-A-0 has no monitor section
[    10.567] (II) AMDGPU(0): Output DVI-D-0 has no monitor section
[    10.568] (II) AMDGPU(0): EDID for output DisplayPort-0
[    10.568] (II) AMDGPU(0): EDID for output HDMI-A-0
[    10.568] (II) AMDGPU(0): EDID for output DVI-D-0
[    10.568] (II) AMDGPU(0): Manufacturer: ACR  Model: 5e  Serial#: 2469468629
[    10.568] (II) AMDGPU(0): Year: 2009  Week: 33
[    10.568] (II) AMDGPU(0): EDID Version: 1.3

I just tested on the Linux Mint 19.1 machine (Nvidia GTX 1050 with proprietary drivers). I booted up with only the monitor I’m trying to use for my second display (ViewSonic vx2035wm), then connected her monitor to the DVI port (I thought she only had HDMI) and dual display worked right away.

Upon searching the output of cat /var/log/Xorg.0.log , I see no EDID line with the Nvidia card. Mint 19.1 does recognize the monitor make/model and specs. Not sure what information you may be referring to here.

The Mint machine is using a Samsung SyncMaster 206BW. I may play musical monitors to see what I can get for a dual display. Maybe its the ViewSonic monitor that MATE doesn’t like?

Sorry I’m very technical. I’m learning a lot though thanks to this awesome community :slight_smile:

Here is a reddit thread on this issue I’m having:

Thanks to some help I got there I had the monitor showing up by this process:

[email protected]:~$ xrandr --output HDMI-A-0 --mode 1680x1050_60.00
xrandr: cannot find mode 1680x1050_60.00
[email protected]:~$ xrandr --newmode “1680x1050_60.00” 146.25 1680 1784 1960 2240 1050 1053 1059 1089 -hsync +vsync
[email protected]:~$ xrandr --addmode HDMI-A-0 1680x1050_60.00
[email protected]:~$ xrandr --output HDMI-A-0 --mode 1680x1050_60.00
[email protected]:~$ xrandr --listmonitors
Monitors: 2
0: +*DVI-D-0 1920/531x1080/299+0+0 DVI-D-0
1: +HDMI-A-0 1680/444x1050/278+0+0 HDMI-A-0


#4

The HDMI to DVI cable is missing the DDC lines.

The missing DDC is why you have to specify the video with the “xrandr” command.

What is the model of the Viewsonic monitor? Some of the older monitors had bad EDID data, but I’m not aware of any LCD monitors with bad EDID data.

As you have discovered, the primary display is not as sensitive to missing info as the secondary display.

Linux Mint should have an EDID line in the Xorg.0.log file. The NVidia propriety drivers may suppress that info (why? - I don’t know). The opensource nouveau driver does log EDID info.

djb


#5

Thanks for all your help and information. I am going to read up on this link.

I believe it is the monitor side of things. It is a ViewSonic VX2035wm. I swapped monitors with my kids machine. The Samsung SyncMaster 206BW she was using worked as soon as I plugged it in, with the same cable. She will have to suffer with the ‘loner screen’ that’s been floating around the house. At least it works on her machine. I need 2 displays so I can work in full-screen Blender with a full display tutorial on the side.


#6

I thought that monitor sounded familiar.

  • and this -

djb