Bug 21404 - [830M] dithering not enabled correctly
Summary: [830M] dithering not enabled correctly
Alias: None
Product: xorg
Classification: Unclassified
Component: Driver/intel (show other bugs)
Version: unspecified
Hardware: x86 (IA32) Linux (All)
: medium normal
Assignee: Jesse Barnes
QA Contact: Xorg Project Team
Keywords: NEEDINFO
Depends on:
Reported: 2009-04-25 08:00 UTC by Jaakko Oranen
Modified: 2009-06-23 17:25 UTC (History)
0 users

See Also:
i915 platform:
i915 features:

Xorg.0.log (43.15 KB, text/plain)
2009-04-30 07:24 UTC, Jaakko Oranen
no flags Details
dmesg (33.54 KB, text/plain)
2009-04-30 07:25 UTC, Jaakko Oranen
no flags Details
xrandr output (1.49 KB, text/plain)
2009-04-30 07:26 UTC, Jaakko Oranen
no flags Details
xorg.conf (752 bytes, application/octet-stream)
2009-04-30 07:27 UTC, Jaakko Oranen
no flags Details
vbios (64.00 KB, application/octet-stream)
2009-04-30 11:15 UTC, Jaakko Oranen
no flags Details

Description Jaakko Oranen 2009-04-25 08:00:29 UTC
Intel-driver does not enable dithering on Dell Latitude C400. The result is that there is "banding" instead of a smooth transition between colors. It is especially apparent when there is any kind of gradient on the screen.

The problem is probably that the C400 has 6-bit LCD-panel and Intel-driver doesn't probe the panel properly. The driver doesn't know that the dithering should be enabled for this panel.
Comment 1 Jesse Barnes 2009-04-28 18:43:15 UTC
I'll need some logs (dmesg, X log and other info requested in http://intellinuxgraphics.org/how_to_report_bug.html), but it may be a a dup of #21446 if you're using KMS.
Comment 2 Jaakko Oranen 2009-04-30 07:24:46 UTC
Created attachment 25305 [details]
Comment 3 Jaakko Oranen 2009-04-30 07:25:49 UTC
Created attachment 25306 [details]
Comment 4 Jaakko Oranen 2009-04-30 07:26:20 UTC
Created attachment 25307 [details]
xrandr output
Comment 5 Jaakko Oranen 2009-04-30 07:27:06 UTC
Created attachment 25308 [details]
Comment 6 Jaakko Oranen 2009-04-30 07:40:48 UTC
Distribution: Arch Linux
Xorg version: 1.6.1
Intel-driver version: 2.3.2
libdrm version: 2.4.9
DRI-driver version: 7.4
Comment 7 Jaakko Oranen 2009-04-30 11:15:36 UTC
Created attachment 25315 [details]
Comment 8 Jesse Barnes 2009-06-23 17:25:09 UTC
Does this still happen on more recent versions?  AFAICT we set the dither bit on all DVO attached panels, so please re-open if it still fails with the 2.7.1 driver for example (or file a new bug if you see a different issue).

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