[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

[bugzilla-daemon]

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https://bugs.freedesktop.org/show_bug.cgi?id=106006

            Bug ID: 106006
           Summary: Kernel 4.16.0+ switch amdgpu.dc=1 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 amdgpu.dc=1 switch in the
kernel.

Test to get to this point:

* boot PC - (Grub screen brightness is "normal")
* Set kernel value amdgpu.dc=1 and proceed with 4.16.0+ kernel boot - (kernel
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 equivalent
to manual setting I can't actually discern. It's not brightness, necessarily,
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=0 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=0 and amdgpu.dc=1. Let me know if you need any
other logs.

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

[bugzilla-daemon]

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https://bugs.freedesktop.org/show_bug.cgi?id=106006

--- Comment #1 from Joel Sass <sass.joel@gmail.com> ---
Created attachment 138804
  --> https://bugs.freedesktop.org/attachment.cgi?id=138804&action=edit
dmesg output with amdgpu.dc=0

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

[bugzilla-daemon]

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https://bugs.freedesktop.org/show_bug.cgi?id=106006

--- Comment #2 from Joel Sass <sass.joel@gmail.com> ---
Created attachment 138805
  --> https://bugs.freedesktop.org/attachment.cgi?id=138805&action=edit
Xorg.0.log with amdgpu.dc=0

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

[bugzilla-daemon]

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https://bugs.freedesktop.org/show_bug.cgi?id=106006

--- Comment #3 from Joel Sass <sass.joel@gmail.com> ---
Created attachment 138806
  --> https://bugs.freedesktop.org/attachment.cgi?id=138806&action=edit
xrandr --verbose with amdgpu.dc=0

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

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https://bugs.freedesktop.org/show_bug.cgi?id=106006

--- Comment #4 from Joel Sass <sass.joel@gmail.com> ---
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 rendering
characteristic, not necessarily brightness - It's like color rendering or gamma
correction change somehow. Simply changing the brightness a modicum seems to
fix the issue.

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

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https://bugs.freedesktop.org/show_bug.cgi?id=106006

--- Comment #5 from Joel Sass <sass.joel@gmail.com> ---
Created attachment 138807
  --> https://bugs.freedesktop.org/attachment.cgi?id=138807&action=edit
xrandr --verbose with amdgpu.dc=1

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

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https://bugs.freedesktop.org/show_bug.cgi?id=106006

--- Comment #6 from Joel Sass <sass.joel@gmail.com> ---
Created attachment 138808
  --> https://bugs.freedesktop.org/attachment.cgi?id=138808&action=edit
Xorg.0.log with amdgpu.dc=1

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

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https://bugs.freedesktop.org/show_bug.cgi?id=106006

--- Comment #7 from Joel Sass <sass.joel@gmail.com> ---
Created attachment 138809
  --> https://bugs.freedesktop.org/attachment.cgi?id=138809&action=edit
dmesg output with amdgpu.dc=1

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

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https://bugs.freedesktop.org/show_bug.cgi?id=106006

--- Comment #8 from Joel Sass <sass.joel@gmail.com> ---
$ 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:   
core-9.20160110ubuntu0.2-amd64:core-9.20160110ubuntu0.2-noarch:security-9.20160110ubuntu0.2-amd64:security-9.20160110ubuntu0.2-noarch
Distributor ID: Ubuntu
Description:    Ubuntu 16.04.4 LTS
Release:        16.04
Codename:       xenial

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

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https://bugs.freedesktop.org/show_bug.cgi?id=106006

Michel Dänzer <michel@daenzer.net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |harry.wentland@amd.com

--- Comment #9 from Michel Dänzer <michel@daenzer.net> ---
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.

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

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https://bugs.freedesktop.org/show_bug.cgi?id=106006

--- Comment #10 from Harry Wentland <harry.wentland@amd.com> ---
Created attachment 138814
  --> https://bugs.freedesktop.org/attachment.cgi?id=138814&action=edit
[PATCH] drm/amd/display: Don't program bypass on linear regamma LUT

Does this fix things for you?

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

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https://bugs.freedesktop.org/show_bug.cgi?id=106006

--- Comment #11 from Joel Sass <sass.joel@gmail.com> ---
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://github.com/M-Bab/linux-kernel-amdgpu-binaries

I downloaded the source listed in the first link I posted above, and it doesn'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.

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

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--- Comment #12 from Joel Sass <sass.joel@gmail.com> ---
Created attachment 139022
  --> https://bugs.freedesktop.org/attachment.cgi?id=139022&action=edit
I don't think this is the same file from 2.17. Sorry.

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

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https://bugs.freedesktop.org/show_bug.cgi?id=106006

--- Comment #13 from Harry Wentland <harry.wentland@amd.com> ---
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 apply.

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

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https://bugs.freedesktop.org/show_bug.cgi?id=106006

--- Comment #14 from Joel Sass <sass.joel@gmail.com> ---
Sorry, I completely forgot that I was using a custom kernel. I downloaded it
from here:

https://github.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

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

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--- Comment #15 from Joel Sass <sass.joel@gmail.com> ---
This bug has been fixed in this branch: h

https://cgit.freedesktop.org/~agd5f/linux/log/?h=drm-fixes-4.17

brightness appears as normal after building the kernel from git.

Good job, and thanks.

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[Bug 106006] Kernel 4.16.0+ switch amdgpu.dc=1 causes screen brightness set to 1 to be dimmed by default

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Joel Sass <sass.joel@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED

--- Comment #16 from Joel Sass <sass.joel@gmail.com> ---
Whoops. Changing to resolved/fixed.

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