Bug 415657

Summary:	Can't set screen resolution to 1280x1024
Product:	[Applications] systemsettings	Reporter:	falling_failing_falling
Component:	kcm_kscreen	Assignee:	kscreen-bugs-null <kscreen-bugs-null>
Status:	RESOLVED NOT A BUG
Severity:	normal	CC:	nate, plasma-bugs-null
Priority:	NOR
Version First Reported In:	5.14.3
Target Milestone:	---
Platform:	Neon
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description falling_failing_falling 2019-12-28 19:36:05 UTC

SUMMARY
The screen I'm currently using is a 1280x1024 Sony SDM-HS73 (from 15+ years ago). I tried a lot of time to set the screen resolution to 1280x1024 on KDE neon, but it's still stuck at 1024x768. 

So I tried those commands :
cvt 1280 1024 60
sudo xrandr --newmode "1280x1024_60.00"  109.00  1280 1368 1496 1712  1024 1027 1034 1063 -hsync +vsync
sudo xrandr --addmode VGA-0 1280x1024_60.00
sudo xrandr -s 1280x1024 -r 60

The third command (sudo xrandr --addmode VGA-0 1280x1024_60.00) isn't working :
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:  29
  Current serial number in output stream:  30


The graphic card on the computer is an ZOTAC GTS 250 that support up to OpenGL 3.3 and 1920x1080. At least it's working on X but I also want to test it on Wayland, any tutorial for that?

STEPS TO REPRODUCE
Nothing you can reproduce by yourself if you don't have a 1280 by 1024 screen.

OBSERVED RESULT
Screen size 1280 by 1024 isn't working, stuck on 1024 by 768.

EXPECTED RESULT
Being able to set the screen size to 1280 by 1024.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: KDE neon 5.17.4

Comment 1 falling_failing_falling 2019-12-29 18:58:20 UTC

So I fixed it by doing that : 
nvidia-xconfig to generate the xorg.config file.
sudo nano /etc/X11/xorg.conf to edit the config file.
Inside the config file, I found the "Monitor" section and I edited it :
Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Sony"
    ModelName      "SDM-HS73"
    HorizSync       28.0 - 80.0
    VertRefresh     48.0 - 75.0
    Modeline       "1280x1024_60.00"  109.00  1280 1368 1496 1712  1024 1027 10$
    Option         "DPMS"
EndSection


I also had to change the systemsettings resfresh irate from 60Hz to 75Hz because at 60Hz the horizontal position of the screen wasn't set correctly. 

So it is easy to for someone like me, but not for the "lambda" end user.
So I wish that KDE find a way to automatically detect and position the screen.

Comment 2 falling_failing_falling 2019-12-31 20:37:08 UTC

So I finally found a way to set the screen positioning correctly.
In CVT, you have to type the maximum refresh rate.
So for 60 Hz, use 75 Hz :
cvt 1280 1024 75
sudo nano /etc/X11/xorg.conf to edit the config file.
Inside the config file, I found the "Monitor" section and I edited it :
Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Sony"
    ModelName      "SDM-HS73"
    HorizSync       28.0 - 80.0
    VertRefresh     48.0 - 75.0
    Modeline       "1280x1024_75.00"  138.75  1280 1368 1504 1728  1024 1027 1034 1072 -hsync +vsync
    Option         "DPMS"
EndSection