How to disable bottom part of the screen with xrandr

Question

I have tried to use xrandr to resize the screen so only the good parts of the LCD panel are used, but the problem is that I can only blackout/disable the top part of the screen, not the bottom part which is the one broken.

So first I use cvt to get a new mode for xrandr with the new resolution calculated leaving the broken part of the screen out.

cvt 1366 700

Then use this to create a new mode with xrandr

xrandr --newmode 1368x700 77.00 1368 1432 1568 1768 700 703 713 727 -hsync +vsync

Then I setted this mode

xrandr --addmode eDP-1 1368x700
xrandr --output eDP-1 --mode 1368x700

But the part of the screen that gets disabled is the top part of the screen, not the bottom.

How can I disable the bottom part of the screen instead of the top part? Can xrandr be used for this, what else can I use?

Thanks for the help

Answer 1

Fiddling with modeline timings works only with analogue consumers of video signals (real classic monitors with a cathode ray tube).

Creating modelines with actually smaller resolution, resulting in unusual video modes, works only with awesome LCDs, which a) accept strange modes, b) can be configured to not pump them up to monitor size and c) allow you to position the image freely.

Sometimes you get by with a regular priced LCD, which at least allows you to keep the aspect ratio and a center position of your resulting image is good enough.

Otherwise you can go with the following real solution:

Drive the monitor as usual with its 1366x768 resolution (guessing from the question). Then add a virtual monitor, 68 pixels shorter, occupying the upper space, replacing the real monitor:

xrandr --setmonitor my-monitor-0 1366/100x700/50+0+0 eDP-1

Explanation of this line and more examples in this list of my other answers.