Ttyjfyk

I am trying Kubuntu 18.10 and I have a nvidia GTX 1060 (driver 418), a LG 27" 4k monitor (27UD58-B ) and an older HP 22" 1680x1050 monitor (HPw2207) with a VGA cord and a VGA-> DP converter.

My issues are as follow:

1) I can't get my vga screen with converter to use a resolution above 1280*1024

2) I'd like to use screen scaling because everything is so damn small on the 4k display. I'd want the scaling to only be done on the high-dpi display if possible.

Current setup:

I am using Nvidia drivers 418.56.

$ nvidia-smi
Mon Apr 15 15:07:47 2019 
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 418.56 Driver Version: 418.56 CUDA Version: 10.1 |
|-------------------------------+----------------------+----------------------+
| GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
|===============================+======================+======================|
| 0 GeForce GTX 106... Off | 00000000:23:00.0 On | N/A |
| 10% 64C P0 25W / 120W | 739MiB / 6076MiB | 3% Default |
+-------------------------------+----------------------+----------------------+

+-----------------------------------------------------------------------------+
| Processes: GPU Memory |
| GPU PID Type Process name Usage |
|=============================================================================|
| 0 958 G /usr/lib/xorg/Xorg 386MiB |
| 0 1413 G /usr/bin/kwin_x11 192MiB |
| 0 1432 G /usr/bin/krunner 1MiB |
| 0 1434 G /usr/bin/plasmashell 111MiB |
| 0 1509 G /usr/bin/latte-dock 29MiB |
| 0 9387 G /usr/lib/firefox/firefox 1MiB |
+-----------------------------------------------------------------------------+

and normal higher resolutions are not available:

$ xrandr
Screen 0: minimum 8 x 8, current 4864 x 2160, maximum 32767 x 32767
DVI-D-0 disconnected (normal left inverted right x axis y axis)
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-0 connected primary 3840x2160+0+0 (normal left inverted right x axis y axis) 600mm x 340mm
 3840x2160 60.00*+ 30.00 
 2560x1440 59.95 
 1920x1080 60.00 59.94 
 1600x900 60.00 
 1280x1024 60.02 
 1280x800 59.81 
 1280x720 60.00 59.94 
 1152x864 59.96 
 1024x768 60.00 
 800x600 60.32 
 720x480 59.94 
 640x480 59.94 59.93 
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)
DP-4 connected 1024x1280+3840+832 left (normal left inverted right x axis y axis) 376mm x 301mm
 1280x1024 60.02*+
 1280x960 60.00 
 1152x864 75.00 
 1024x768 85.00 75.03 70.07 60.00 
 800x600 85.06 75.00 72.19 
 640x480 85.01 59.94 
DP-5 disconnected (normal left inverted right x axis y axis)

First issue: fixing resolution
I have tried to "addmode" using xrandr, but I get a BadMatch error. This is apparently normal with nvidia video cards.

$ cvt 1680 1050 60
# 1680x1050 59.95 Hz (CVT 1.76MA) hsync: 65.29 kHz; pclk: 146.25 MHz
Modeline "1680x1050_60.00" 146.25 1680 1784 1960 2240 1050 1053 1059 1089 -hsync +vsync
$ xrandr --newmode "1680x1050_60.00" 146.25 1680 1784 1960 2240 1050 1053 1059 1089 -hsync +vsync

$ xrandr --addmode DP-4 1680x1050_60.00
X Error of failed request: BadMatch (invalid parameter attributes)
 Major opcode of failed request: 140 (RANDR)
 Minor opcode of failed request: 18 (RRAddOutputMode)
 Serial number of failed request: 45
 Current serial number in output stream: 46

My /etc/X11/xorg.conf file has been generated by nvidia usind sudo nvidia-xconfig :

$ sudo nvidia-xconfig

Using X configuration file: "/etc/X11/xorg.conf".
Backed up file '/etc/X11/xorg.conf' as '/etc/X11/xorg.conf.backup'
New X configuration file written to '/etc/X11/xorg.conf'

The xorg.conf only contains one monitor, is this normal. I have tried to add a "Modeline" line under the Monitor0, but it didnt change anything.

# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig: version 418.56


Section "ServerLayout"
 Identifier "Layout0"
 Screen 0 "Screen0" 0 0
 InputDevice "Keyboard0" "CoreKeyboard"
 InputDevice "Mouse0" "CorePointer"
EndSection

Section "Files"
EndSection

Section "InputDevice"

 # generated from default
 Identifier "Mouse0"
 Driver "mouse"
 Option "Protocol" "auto"
 Option "Device" "/dev/psaux"
 Option "Emulate3Buttons" "no"
 Option "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"

 # generated from default
 Identifier "Keyboard0"
 Driver "kbd"
EndSection

Section "Monitor"
 Identifier "Monitor0"
 VendorName "Unknown"
 ModelName "Unknown"
 HorizSync 28.0 - 33.0
 VertRefresh 43.0 - 72.0
 Option "DPMS"
EndSection

Section "Device"
 Identifier "Device0"
 Driver "nvidia"
 VendorName "NVIDIA Corporation"
EndSection

Section "Screen"
 Identifier "Screen0"
 Device "Device0"
 Monitor "Monitor0"
 DefaultDepth 24
 SubSection "Display"
 Depth 24
 EndSubSection
EndSection

Second issue : scaling

I have taken two steps to allow the HiDPI screen to display text and GUI in a more readable size:

1) System settings - fonts - Force Font DPI 144 (instead of 96)
2) system settings- display and monitors - scale display 1.5 (instead of 1).

I would lke these settings to only apply to the 4k monitor, is this possible at all?

I found a workaround: I connected my display directly to an old tower that has a VGA and exported the edid using

sudo apt install read-edid
sudo get-edid -m 0 > edid.bin

then I erased the old xorg.conf on the machine and created a new one where I forced the edid for the monitor on display port 4:

sudo rm /etc/X11/xorg.conf 
nvidia-xconfig --custom-edid="GPU-0.DP-4:/home/MYNAME/edid.bin"

Ta-da, the higher resolution now works. When I look at my xorg.conf file, I see the following line has been added to the "Screen" section:

 Option "CustomEDID" "GPU-0.DP-4:/home/MYNAME/Downloads/edid.bin"