[SOLVED] Unable to scale down the resolution to not listed ones

DarioP · 2015-04-25 00:16:51

I have a laptop whose screen has a native resolution of 2880x1620 (16:9).
Along with that, Gnome lists many other smaller resolutions but all of them are 4:3 (one even 5:4).

There are some applications (especially gaming) where I would like to scale down to 1920x1080 or even less, but keeping the 16:9 aspect ratio.
I have been playing with xrandr adding some of those, as explained in the wiki. However when I try to activate them, the screen goes black for a while and then comes back as before without any error.

Any idea? Is there a place where I should look for logs?

Last edited by DarioP (2015-04-30 15:27:37)

DarioP · 2015-04-25 15:35:41

I didn't plan to, but I decided to install Windows on my second sdd to try it a bit.

I was so sad seeing that win detects (and applies) so many more screen resolutions, included 1920x1080 and 1600x900.
I tried to extract the modelines with PowerStrip, but still no luck with xrandr: the screen goes black, flashes, black again and back at the starting point.

Sometimes Linux - pardon, Xorg - is so annoying...

R00KIE · 2015-04-25 16:50:23

Make sure you try both gtf and cvt to generate the modelines, both give slightly different values and you maybe be able to get one to work.

Also don't forget that the display might accept only one refresh frequency (or something very slightly above or below) and refuse to work with anything else.

DarioP · 2015-04-26 09:10:32

I did a quite systematic work testing all of these:

#gtf 1600 900 60
xrandr --newmode "1600x900_60_0g" 119.00  1600 1696 1864 2128  900 901 904 932  -hsync -vsync
xrandr --newmode "1600x900_60_1g" 119.00  1600 1696 1864 2128  900 901 904 932  +hsync -vsync
xrandr --newmode "1600x900_60_2g" 119.00  1600 1696 1864 2128  900 901 904 932  -hsync +vsync
xrandr --newmode "1600x900_60_3g" 119.00  1600 1696 1864 2128  900 901 904 932  +hsync +vsync

#gtf 1600 900 59
xrandr --newmode "1600x900_59_0g" 116.89  1600 1696 1864 2128  900 901 904 931  -HSync -Vsync
xrandr --newmode "1600x900_59_1g" 116.89  1600 1696 1864 2128  900 901 904 931  -HSync +Vsync
xrandr --newmode "1600x900_59_2g" 116.89  1600 1696 1864 2128  900 901 904 931  +HSync -Vsync
xrandr --newmode "1600x900_59_3g" 116.89  1600 1696 1864 2128  900 901 904 931  +HSync +Vsync

#cvt 1600 900 60
xrandr --newmode "1600x900_60_0c" 118.25  1600 1696 1856 2112  900 903 908 934 -hsync -vsync
xrandr --newmode "1600x900_60_1c" 118.25  1600 1696 1856 2112  900 903 908 934 -hsync +vsync
xrandr --newmode "1600x900_60_2c" 118.25  1600 1696 1856 2112  900 903 908 934 +hsync -vsync
xrandr --newmode "1600x900_60_3c" 118.25  1600 1696 1856 2112  900 903 908 934 +hsync +vsync

#cvt 1600 900 59
xrandr --newmode "1600x900_59_0c" 116.25  1600 1696 1856 2112  900 903 908 934 -hsync -vsync
xrandr --newmode "1600x900_59_1c" 116.25  1600 1696 1856 2112  900 903 908 934 -hsync +vsync
xrandr --newmode "1600x900_59_2c" 116.25  1600 1696 1856 2112  900 903 908 934 +hsync -vsync
xrandr --newmode "1600x900_59_3c" 116.25  1600 1696 1856 2112  900 903 908 934 +hsync +vsync

#cvt -r 1600 900 60
xrandr --newmode "1600x900R0" 97.50  1600 1648 1680 1760  900 903 908 926 -hsync -vsync
xrandr --newmode "1600x900R1" 97.50  1600 1648 1680 1760  900 903 908 926 -hsync +vsync
xrandr --newmode "1600x900R2" 97.50  1600 1648 1680 1760  900 903 908 926 +hsync -vsync
xrandr --newmode "1600x900R3" 97.50  1600 1648 1680 1760  900 903 908 926 +hsync +vsync

All of them fails

I also tried:

$ xrandr  --fb 1600x900
xrandr: specified screen 1600x900 not large enough for output eDP1 (2880x1620+0+0)

The screen resolution remains 2880x1620 but I can only move the mouse in a square, presumably sized 1600x900, in the top left corner, the rest is black

Last edited by DarioP (2015-04-26 09:20:03)

R00KIE · 2015-04-26 11:17:46

Silly question, you did do 'xrandr --addmode output_name modeline_name' for each of the modelines right?

If you did then I guess there are two things you can try:
- add the modeline you want in a monitor.conf file for X to read and see if sticks
- try to force an EDID for that monitor with the added resolution(s) you want and hope the monitor doesn't complain

For the second option you might benefit from taking note of the available mode on windows and the exact settings for each one.

DarioP · 2015-04-30 14:07:21

I succeeded in setting lower resolutions. The problem were the modelines that I was using.

I have found a list here: https://www.xpra.org/xorg.conf and with those it sticks.

However the pixel rate in those modelines is quite low (both compared to my native ones, and the ones of cvt/gtf) and I note a reduction of the responsiveness of the screen when using them.

So the point is now how to find proper modelines... I have found some explanations here: http://howto-pages.org/ModeLines/ I'll try to scale the working ones.

Last edited by DarioP (2015-04-30 15:29:19)

DarioP · 2015-04-30 15:24:32

...and I fixed the pixel rate too!

Using:

xrandr --verbose

I noted that the vertical clocks detected by xorg were all close to 60Hz, while the one I added were much lower.
So I multiplied the pixel rate (the first number in the modeline) by an integer in order to get closer to 60 Hz.

To make it persistent I put everything in a conf file:

$ cat /etc/X11/xorg.conf.d/10-monitor.conf 
Section "Monitor"
  Identifier "Monitor0"
#  Modeline "1920x1080" 23.53 1920 1952 2040 2072 1080 1106 1108 1135
#  Modeline "1600x900" 33.92 1600 1632 1760 1792 900 921 924 946
  Modeline "1920x1080" 141.18 1920 1952 2040 2072 1080 1106 1108 1135
  Modeline "1600x900" 101.76 1600 1632 1760 1792 900 921 924 946
EndSection

Section "Screen"
  Identifier "Screen0"
  Device "eDP1"
  Monitor "Monitor0"
  DefaultDepth 24
  SubSection "Display"
    Depth 24
    Modes "2880x1620" "1920x1080" "1600x900"
  EndSubSection
EndSection

This works for me but I don't suggest to copy and paste it! You may need to adjust the device and find the modelines that works for you.
I kept the auto-detected native resolution of "2880x1620" in order to have it on the top of the list.

I still have no idea why both cvt and gtf failed in getting working modelines for me, but now I can finally use my Linux to play games too

Last edited by DarioP (2015-04-30 15:35:12)

Arch Linux

#1 2015-04-25 00:16:51

[SOLVED] Unable to scale down the resolution to not listed ones

#2 2015-04-25 15:35:41

Re: [SOLVED] Unable to scale down the resolution to not listed ones

#3 2015-04-25 16:50:23

Re: [SOLVED] Unable to scale down the resolution to not listed ones

#4 2015-04-26 09:10:32

Re: [SOLVED] Unable to scale down the resolution to not listed ones

#5 2015-04-26 11:17:46

Re: [SOLVED] Unable to scale down the resolution to not listed ones

#6 2015-04-30 14:07:21

Re: [SOLVED] Unable to scale down the resolution to not listed ones

#7 2015-04-30 15:24:32

Re: [SOLVED] Unable to scale down the resolution to not listed ones

Board footer