Bug 104090

Summary:

Reduced colors on RX580 through eDP on Asus GL702ZC laptop

Product:

DRI

Reporter:

Hein-Pieter van Braam <hp>

Component:

DRM/AMDgpu

Assignee:

Default DRI bug account <dri-devel>

Status:

RESOLVED FIXED

QA Contact:

Severity:

normal

Priority:

medium

CC:

harry.wentland, jordan.lazare, tones111

Version:

DRI git

Keywords:

regression

Hardware:

x86-64 (AMD64)

OS:

Linux (All)

Whiteboard:

i915 platform:

i915 features:

Attachments:

Description	Flags
Without DC: Gnome shell overview	none
DC: Gnome shell overview	none
DC: Gnome shell shutdown dialog	none
Without DC: Gnome shell shutdown dialog	none
Without DC: xrandr --prop output	none
Without DC: Xorg.log	none
Without DC: dmesg -T	none
DC: xrandr --prop output	none
DC: Xorg.log	none
DC: dmesg -T	none
Fix truncate programming	none

Description Hein-Pieter van Braam 2017-12-04 22:39:16 UTC

When enabling DC on the RX580 on Linux 4.15.0-rc2 I get a reduced color palette compared to having DC turned off. 

My setup: 
Fedora 27
Xorg 1.19.5
Xorg drivers amdgpu 1.3.0
Linux 4.15.0-rc2

Attached you will find dmesg, xorg, and xrandr output with and without DC along with 2 pictures with and without dc for the results that I'm talking about.

Comment 1 Hein-Pieter van Braam 2017-12-04 22:39:51 UTC

Created attachment 135946 [details]
Without DC: Gnome shell overview

Comment 2 Hein-Pieter van Braam 2017-12-04 22:40:37 UTC

Created attachment 135947 [details]
DC: Gnome shell overview

Comment 3 Hein-Pieter van Braam 2017-12-04 22:41:15 UTC

Created attachment 135948 [details]
DC: Gnome shell shutdown dialog

Comment 4 Hein-Pieter van Braam 2017-12-04 22:41:41 UTC

Created attachment 135949 [details]
Without DC: Gnome shell shutdown dialog

Comment 5 Hein-Pieter van Braam 2017-12-04 22:42:13 UTC

Created attachment 135950 [details]
Without DC: xrandr --prop output

Comment 6 Hein-Pieter van Braam 2017-12-04 22:42:35 UTC

Created attachment 135951 [details]
Without DC: Xorg.log

Comment 7 Hein-Pieter van Braam 2017-12-04 22:42:57 UTC

Created attachment 135952 [details]
Without DC: dmesg -T

Comment 8 Hein-Pieter van Braam 2017-12-04 22:43:19 UTC

Created attachment 135953 [details]
DC: xrandr --prop output

Comment 9 Hein-Pieter van Braam 2017-12-04 22:43:36 UTC

Created attachment 135954 [details]
DC: Xorg.log

Comment 10 Hein-Pieter van Braam 2017-12-04 22:43:57 UTC

Created attachment 135955 [details]
DC: dmesg -T

Comment 11 Michel Dänzer 2017-12-05 10:26:45 UTC

The EDID says 6 bits per channel, maybe DC doesn't enable dithering.

Comment 12 Hein-Pieter van Braam 2017-12-06 15:22:26 UTC

How do I establish whether that is what is happening or not? It sure looks like that's what's going on though.

Comment 13 Harry Wentland 2017-12-07 16:27:39 UTC

Created attachment 136035 [details] [review]
Fix truncate programming

Does this help? Haven't had a chance to test it myself but this code looked obviously wrong.

Comment 14 Hein-Pieter van Braam 2017-12-07 16:40:40 UTC

I applied attachment 136035 [details] [review] to 4.15.0-rc2 but the problem remained with dc=1 on my rx580 I'm afraid.

Comment 15 Hein-Pieter van Braam 2018-02-16 10:02:47 UTC

I just upgraded to 4.16.0-rc1 and the problem is still there with dc=1

Comment 16 Hein-Pieter van Braam 2018-03-26 12:57:09 UTC

It appears that 4.16.0-rc7 fixed the issue on this laptop. I'll do a bit more testing but it seems on par with a system without dc now. Great stuff.

Comment 17 Harry Wentland 2018-03-27 15:25:54 UTC

Thanks for testing. I'll set this to resolved. If you still see issues feel free to reopen.

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