Bug 1299330

Summary: UltraHD display appears as if resolution is reduced
Product: [Fedora] Fedora Reporter: D. Hugh Redelmeier <hugh>
Component: xorg-x11-drv-nouveauAssignee: Ben Skeggs <bskeggs>
Status: CLOSED EOL QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: unspecified    
Version: 23CC: airlied, ajax, bskeggs
Target Milestone: ---   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2016-12-20 17:58:14 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Attachments:
Description Flags
picture of terminal under nouveau (bad)
none
picture of terminal under proprietary nvidia (good)
none
log of nouveau driver
none
log of nvidia driver none

Description D. Hugh Redelmeier 2016-01-18 06:56:35 UTC
Created attachment 1115754 [details]
picture of terminal under nouveau (bad)

Description of problem:
On my 3840x2160@30 display, driven by a GTX 650 via HDMI 1.x using Nouveau, characters are very hard to read in a terminal.

If I switch to the proprietary nvidia driver, all is well.

(See attached photos of a terminal window.)

Version-Release number of selected component (if applicable):
xorg-x11-drv-nouveau-1.0.12-1.fc23.x86_64


How reproducible:
Always

Steps to Reproduce:
1. display text in a terminal
2. try to read it.

Actual results:
Very hard to read

Expected results:
Easy to read.

Additional info:

I'm attaching two reconstructions of the Xorg.0.log (darn journald for making this hard): one for nouveau and one for proprietary nvidia drive.

I'm also attaching a photograph of a term when running nouveau and one when running the proprietary nvidia driver.  Both photos appear to suffer from moire effects.

This problem has been around for a long time.  At least since Fedora 22, but I'm sure longer than that.

I'm guessing that this is some kind of clocking problem because transitions from black to white or vice versa seem to be reduced.

On the other hand, it might be something else.  For example, the monitor can only work with 4:2:2 chroma subsampling and if the driver isn't doing this, something bad will happen.

Comment 1 D. Hugh Redelmeier 2016-01-18 06:58:26 UTC
Created attachment 1115755 [details]
picture of terminal under proprietary nvidia (good)

Comment 2 D. Hugh Redelmeier 2016-01-18 07:00:00 UTC
Created attachment 1115756 [details]
log of nouveau driver

Comment 3 D. Hugh Redelmeier 2016-01-18 07:00:42 UTC
Created attachment 1115757 [details]
log of nvidia driver

Comment 4 Fedora End Of Life 2016-11-24 15:01:00 UTC
This message is a reminder that Fedora 23 is nearing its end of life.
Approximately 4 (four) weeks from now Fedora will stop maintaining
and issuing updates for Fedora 23. It is Fedora's policy to close all
bug reports from releases that are no longer maintained. At that time
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of '23'.

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Comment 5 Fedora End Of Life 2016-12-20 17:58:14 UTC
Fedora 23 changed to end-of-life (EOL) status on 2016-12-20. Fedora 23 is
no longer maintained, which means that it will not receive any further
security or bug fix updates. As a result we are closing this bug.

If you can reproduce this bug against a currently maintained version of
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