#StackBounty: #display #resolution #xorg #xrandr #modeline An attempt to switch to a doublescan X11 modeline fails with "Configure…

Bounty: 50

I have a modern 1920x1200 LED display, capable of up to 96 kHz HorizSync, up to 76 Hz VertRefresh, and up to 205 MHz pixel clock.

Apart from its native resolution, the display can also run in 1600x1200 (4:3) resolution at 75 Hz:

  1600x1200 (0xa1) 202.500MHz +HSync +VSync
        h: width  1600 start 1664 end 1856 total 2160 skew    0 clock  93.75KHz
        v: height 1200 start 1201 end 1204 total 1250           clock  75.00Hz

Now, I’m trying to switch it to a 800x600 doublescan mode equivalent to the above 1600x1200 mode (at 75 Hz, too; all modelines taken from here):

xrandr --newmode "800x600d" 101.25 800 832 928 1080 600 600 602 625 DoubleScan +HSync +VSync
xrandr --addmode DP1 800x600d

The resulting video mode gets added successfully and is clearly visible in the output of xrandr:

  800x600d (0x1f7) 101.250MHz +HSync +VSync DoubleScan
        h: width   800 start  832 end  928 total 1080 skew    0 clock  93.75KHz
        v: height  600 start  600 end  602 total  625           clock  75.00Hz

But once I attempt to switch to the new mode, I immediately receive an error:

# Mode by name
$ xrandr --output DP1 --mode 800x600d
xrandr: cannot find mode 800x600d

# Mode by id
$ xrandr --output DP1 --mode 0x1f7
xrandr: Configure crtc 0 failed

Are modern graphics cards no longer able to run in a doublescan mode?
Or should I blame my display?

Get this bounty!!!

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