Hi,
Actually, I think you need to know that… in most case, it is not the kernel to make the decision. It is the userspace tool to decide what configuration kernel should use.
For example, when you are in graphic mode, it is the Xorg to decide which mode (resolution) to use. Kernel just reads the EDID and show the Xorg the list. The one chooses the mode is Xorg, not kernel.
Similar case to your color range problem. Xorg will decide which range to use.
Since you disabled the graphic, which means Xorg is being disabled, you should decide which userspace tool you want to use to control the kernel.
An easy way to use is running the gst sink node.
gst-launch-1.0 videotestsrc ! 'video/x-raw, width=800,height=600, framerates=60/1' ! nvvidconv ! nvcompositor ! nvdrmvideosink set-mode=1 color_range=1 //LIMITED COLOR RANGE
gst-launch-1.0 videotestsrc ! 'video/x-raw, width=800,height=600, framerates=60/1' ! nvvidconv ! nvcompositor ! nvdrmvideosink set-mode=1 color_range=0 //FULL RANGE