| Bug ID | 106006 |
|---|---|
| Summary | Kernel 4.16.0+ switch amdgpu.dc=3D1 causes screen brightness = set to 1 to be dimmed by default |
| Product | DRI |
| Version | unspecified |
| Hardware | x86-64 (AMD64) |
| OS | Linux (All) |
| Status | NEW |
| Severity | normal |
| Priority | medium |
| Component | DRM/AMDgpu |
| Assignee | dri-devel@lists.freedesktop.org |
| Reporter | sass.joel@gmail.com |
I'm noticing that the default screen brightness of my desktop = when logged in is set to something beneath "1" when set to "1" with amdgp= u.dc=3D1 switch in the kernel. Test to get to this point: * boot PC - (Grub screen brightness is "normal") * Set kernel value amdgpu.dc=3D1 and proceed with 4.16.0+ kernel boot - (ke= rnel switches quiet and splash removed, brightness appears normal during boot process) * Lightdm display manager starts (brightness is still "normal") * Log in to any window manager, When X starts, the desktop is immediately darkened with what appears to be a high contrast setting. Looks like equiva= lent to manual setting I can't actually discern. It's not brightness, necessaril= y, but the net effect on the desktop is that everything is effectively darker. * I've tested this with Ubuntu's Unity desktop, and gnome-flashback (compiz= and metacity), and it behaves the same. When amdgpu.dc=3D0 is set, desktop appears a normal level of brightness when logging in. It appears from the Xorg.0.log that the AMDGPU module isn't used for X, but brightness isn't affected. I'll include logs from amdgpu.dc=3D0 and amdgpu.dc=3D1. Let me know if you = need any other logs.
Created attachme=
nt 138804 [details]
dmesg output with amdgpu.dc=3D0
Created attachment=
138805 [details]
Xorg.0.log with amdgpu.dc=3D0
Created atta=
chment 138806 [details]
xrandr --verbose with amdgpu.dc=3D0
A fix I've found for the issue seems to be issueing an xrandr = brightness command to each monitor output. EG: ~$ xrandr --output DP-5 --brightness .99 If brightness is set to 1, the monitor appears to lose some sort of renderi= ng characteristic, not necessarily brightness - It's like color rendering or g= amma correction change somehow. Simply changing the brightness a modicum seems to fix the issue.
Created atta=
chment 138807 [details]
xrandr --verbose with amdgpu.dc=3D1
Created attachment=
138808 [details]
Xorg.0.log with amdgpu.dc=3D1
Created attachme=
nt 138809 [details]
dmesg output with amdgpu.dc=3D1
$ uname -a Linux nope 4.16.0+ #1 SMP Mon Apr 2 15:52:14 CEST 2018 x86_64 x86_64 x86_64 GNU/Linux ~$ lsb_release -a LSB Version:=20=20=20 core-9.20160110ubuntu0.2-amd64:core-9.20160110ubuntu0.2-noarch:security-9.2= 0160110ubuntu0.2-amd64:security-9.20160110ubuntu0.2-noarch Distributor ID: Ubuntu Description: Ubuntu 16.04.4 LTS Release: 16.04 Codename: xenial
| What | Removed | Added |
|---|---|---|
| CC | harry.wentland@amd.com |
For DC developers: behind the scenes, brightness 1 means no-op= /pass-through gamma LUT, lower brightness levels are simulated by modifying the gamma LUT accordingly.
Created attachment 138814 [details] [review] [PATCH] drm/amd/display: Don't program bypass on linear regamma LUT Does this fix things for you?
Okay, sadly, I wasn't clear about the kernel I was running. It= 's located here: https://github.com= /M-Bab/linux-kernel-amdgpu and I installed the .deb created by the git contributor here: https://g= ithub.com/M-Bab/linux-kernel-amdgpu-binaries I downloaded the source listed in the first link I posted above, and it doe= sn't appear to have the same file structure you'd listed in your patch. I've attached amdgpu_dm_color.c to this bug. If you don't want to patch for this, I understand. I can see if I can speak= to the person responsible for this repo.
Created attachment 139022 [details]
I don't think this is the same file from 2.17. Sorry.
Not sure exactly how that kernel is assembled but it contains = the problematic code in drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c. You should= be able to simply delete the block for if (__is_lut_linear(...)) in amdgpu_dm_set_regamma_lut to fix this, if the patch doesn't straight-up app= ly.
Sorry, I completely forgot that I was using a custom kernel. I= downloaded it from here: https://g= ithub.com/M-Bab/linux-kernel-amdgpu-binaries and installed the .deb files directly. Here's the source: https://github.com/M-Bab/linux-kernel-amdgpu
This bug has been fixed in this branch: h https://cgit.freedesktop.org/~agd5f/linux/log/?h=3Ddrm-fixes-4.17 brightness appears as normal after building the kernel from git. Good job, and thanks.
| What | Removed | Added |
|---|---|---|
| Resolution | --- | FIXED |
| Status | NEW | RESOLVED |