How do I correct for overscan when using the nouveau display driver?

Question

I have 2 Zotac Zbox HD-ID11 systems which have NVIDIA ION graphics hardware. Both are running Debian 8 (kernel 4.3) with lightdm and the xfce desktop, however one is using the NVIDIA display drivers and the other is using nouveau. Both have TVs connected on the HDMI output but neither TV has the option to correct for overscan.

On the system with the NVIDIA driver (which actually has standard monitor [1280x1024] connected as well as an HD Ready [1280x720] TV) I can use nvidia-setting to correct for the TV's overscan by adjusting the viewport.

The exact command I use is:

nvidia-settings --assign CurrentMetaMode="DPY-1: nvidia-auto-select @1280x1024 +0+0, DPY-2: 1280x720+1280+0 { ViewPortOut=1200x670+40+25 ViewPortIn=1280x720 }"

This reduces the displayed height by 80 pixels and the displayed width by 50 pixels and recenters the desktop by adjusting the offset.

Obviously, the nvidia-settings command does not exist on the system running Nouveau. It has a Full HD [1920x1080] TV connected, so I would need to experiment to determine the exact parameters, but what would be the equivalent command line tool or configuration setting to adjust the viewport using Nouveau?

Answer 1

After further searching, I found this bug report which indicates that a potential fix was added in 2012, although the issue is not considered properly resolved.

In any event, the workaround ppears to be the commands:

xrandr --output HDMI-1 --set underscan on
xrandr --output HDMI-1 --set "underscan hborder" 54 --set "underscan vborder" 51

Obviously the numbers may need adjusting by trial and error.

At least the edges of my desktop are no longer cut off!