Bug 111452 - Dull colors with kernel 5.2.0 on external monitors with intel-gfx
Summary: Dull colors with kernel 5.2.0 on external monitors with intel-gfx
Status: NEW
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/Intel (show other bugs)
Version: XOrg git
Hardware: x86-64 (AMD64) Linux (All)
: not set not set
Assignee: Intel GFX Bugs mailing list
QA Contact: Intel GFX Bugs mailing list
URL:
Whiteboard: Triaged
Keywords:
Depends on:
Blocks:
 
Reported: 2019-08-21 10:27 UTC by Bernd Buschinski
Modified: 2019-08-23 08:49 UTC (History)
2 users (show)

See Also:
i915 platform: SKL
i915 features: display/color management


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Description Bernd Buschinski 2019-08-21 10:27:56 UTC
With kernel 5.2.0 my colors on my external monitors are kind of dull.
Meaning the contrast seems lower and the gamma seems higher.
It worked fine with kernel 5.1.0.

It can be worked around with:

xrandr --output DP-1-1 --set 'Broadcast RGB' 'Full'
xrandr --output DP-1-2 --set 'Broadcast RGB' 'Full'

Only the external monitors (connected via laptop -> docking station -> display port) are affected. The laptop display is fine.


I started bisecting it and result is:

37aa52bff2bcd4377c0f747f730f3d436f2fe58e is the first bad commit
commit 37aa52bff2bcd4377c0f747f730f3d436f2fe58e
Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
Date:   Tue Mar 26 16:25:51 2019 +0200

    drm/i915: Add broadcast RGB property for DP MST
    
    Add the "Broadcast RGB" property to MST connectors, and implement
    the same logic for it as we have in the SST code.
    
    v2: Extract and reuse intel_dp_limited_color_range()
    
    Cc: Ivan Vlk <ari@adyline.sk>
    Tested-by: Ivan Vlk <ari@adyline.sk>
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108821
    Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
    Reviewed-by: Jani Nikula <jani.nikula@intel.com> #v1
    Link: https://patchwork.freedesktop.org/patch/msgid/20190326142556.21176-1-ville.syrjala@linux.intel.com

 drivers/gpu/drm/i915/intel_dp.c     | 39 ++++++++++++++++++++++++-------------
 drivers/gpu/drm/i915/intel_dp_mst.c | 15 ++++++++++++--
 drivers/gpu/drm/i915/intel_drv.h    |  2 ++
 3 files changed, 40 insertions(+), 16 deletions(-)



CPU: Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz
Laptop: Dell Latitude E7470
Software:
- xorg-server-1.20.5
- mesa-19.1.3
- libdrm-2.4.99


Kernel Bugzilla Link: https://bugzilla.kernel.org/show_bug.cgi?id=204351
Comment 1 Lakshmi 2019-08-21 12:29:30 UTC
(In reply to Bernd Buschinski from comment #0)
> With kernel 5.2.0 my colors on my external monitors are kind of dull.
> Meaning the contrast seems lower and the gamma seems higher.
> It worked fine with kernel 5.1.0.
> 
> It can be worked around with:
> 
> xrandr --output DP-1-1 --set 'Broadcast RGB' 'Full'
> xrandr --output DP-1-2 --set 'Broadcast RGB' 'Full'
> 
> Only the external monitors (connected via laptop -> docking station ->
> display port) are affected. The laptop display is fine.
> 
> 
> I started bisecting it and result is:
> 
> 37aa52bff2bcd4377c0f747f730f3d436f2fe58e is the first bad commit
> commit 37aa52bff2bcd4377c0f747f730f3d436f2fe58e
> Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Date:   Tue Mar 26 16:25:51 2019 +0200
> 
>     drm/i915: Add broadcast RGB property for DP MST
>     
>     Add the "Broadcast RGB" property to MST connectors, and implement
>     the same logic for it as we have in the SST code.
>     
>     v2: Extract and reuse intel_dp_limited_color_range()
>     
>     Cc: Ivan Vlk <ari@adyline.sk>
>     Tested-by: Ivan Vlk <ari@adyline.sk>
>     Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108821
>     Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
>     Reviewed-by: Jani Nikula <jani.nikula@intel.com> #v1
>     Link:
> https://patchwork.freedesktop.org/patch/msgid/20190326142556.21176-1-ville.
> syrjala@linux.intel.com
> 
>  drivers/gpu/drm/i915/intel_dp.c     | 39
> ++++++++++++++++++++++++-------------
>  drivers/gpu/drm/i915/intel_dp_mst.c | 15 ++++++++++++--
>  drivers/gpu/drm/i915/intel_drv.h    |  2 ++
>  3 files changed, 40 insertions(+), 16 deletions(-)
> 
> 
> 
> CPU: Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz
> Laptop: Dell Latitude E7470
> Software:
> - xorg-server-1.20.5
> - mesa-19.1.3
> - libdrm-2.4.99
> 
> 
> Kernel Bugzilla Link: https://bugzilla.kernel.org/show_bug.cgi?id=204351

@Ville Any comments?
Comment 2 Ville Syrjala 2019-08-21 14:22:11 UTC
Sounds like a broken display that doesn't respect the CEA range bit in MSA. Either that or someone has manually tweaked the "black level" etc. setting on the display to expect full range output always.
Comment 3 Bernd Buschinski 2019-08-23 08:49:01 UTC
What does this actually mean? I hit the "factory reset" on the monitor setting multiple times now.
All color profiles are set to Standard/RGB.

So what can I actually do? Deal with it? How can I help you to debug this further?

From a very "naive" user point of view this is simply a regression, as it used to work fine with kernel <5.2.

Monitor: Dell P2314H (connected via display port)


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