xcalib -invert -alter doesn't work, but increases gamma

[juergendrachta]

On Arch-Linux with AMD APU (amd-xorg drivers), xcalib v. 0.10, the inversion via "xcalib -i -a" but only increases the gamma heavily.

This bug was also reported by others:
https://bugzilla.redhat.com/show_bug.cgi?id=1662620
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=913849
zoltanp/xrandr-invert-colors#20

Driver-Info:

lspci -k | grep -EA3 'VGA|3D|Display'
05:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Picasso (rev c1)
	Subsystem: Lenovo Picasso
	Kernel driver in use: amdgpu
	Kernel modules: amdgpu

[beku]

Thanks for reporting. This issue appears to be a special case. Unfortunately I have no means to test on such a card.
Can you verify the ramps are correctly written?

[juergendrachta]

Thanks for the comment!
Hmm... do you want to see the full output of running xcalib with the "-p" flag (it gives quite a bunch of numbers i cannot say if it's worth copying it :-) )

But I found some interesting thing, when i ran xcalib with "-v":

(base) [...@... ~]$ xcalib -i -a -v
XRandR output:      	eDP
Red Brightness: 0.000000   Contrast: 99.903870  Max: 0.999039  Min: 0.000000
Green Brightness: 0.000000   Contrast: 99.903870  Max: 0.999039  Min: 0.000000
Blue Brightness: 0.000000   Contrast: 99.903870  Max: 0.999039  Min: 0.000000
X-LUT size:      	1024
(base) [...@... ~]$ xcalib -i -a -v
XRandR output:      	eDP
Red Brightness: 99.903870   Contrast: -103925.398438  Max: 0.000000  Min: 0.999039
Green Brightness: 99.903870   Contrast: -103925.398438  Max: 0.000000  Min: 0.999039
Blue Brightness: 99.903870   Contrast: -103925.398438  Max: 0.000000  Min: 0.999039
X-LUT size:      	1024

It seems that the number of the contrast aren't ok (at least I think so by comparing them to the xcalib output of a machine, where the color inversion works properly)!