Bug 44755

Summary: Garbled display on external screen when using 1920x1080 instead of 1920x1200
Product: xorg Reporter: Bryce Harrington <bryce>
Component: Driver/RadeonAssignee: xf86-video-ati maintainers <xorg-driver-ati>
Status: RESOLVED INVALID QA Contact: Xorg Project Team <xorg-team>
Severity: major    
Priority: high CC: thejoe
Version: git   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
Whiteboard:
i915 platform: i915 features:
Attachments:
Description Flags
BootDmesg.txt
none
CurrentDmesg.txt
none
XorgLog.txt
none
possible fix
none
fix none

Description Bryce Harrington 2012-01-13 06:46:04 UTC 
Forwarding this bug from Ubuntu reporter Joe Barnett:
http://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-ati/+bug/915408

[Problem]
i have an external monitor (1920x1200 resolution) that, when set to 1920x1080 resolution (native resolution of laptop display), garbles the screen as seen in the screenshot below.  The problem doesn't happen using the catalyst driver.

https://bugs.launchpad.net/lightdm-gtk-greeter/+bug/813566/+attachment/2221015/+files/2011-07-20_07-51-28_83.jpg

ProblemType: BugDistroRelease: Ubuntu 11.10
Package: xorg 1:7.6+7ubuntu7
ProcVersionSignature: Ubuntu 3.0.0-15.25-generic 3.0.13
Uname: Linux 3.0.0-15-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 1.23-0ubuntu4
Architecture: amd64
CompizPlugins: [core,bailer,detection,composite,opengl,decor,mousepoll,vpswitch,regex,animation,snap,expo,move,compiztoolbox,place,grid,imgpng,gnomecompat,wall,ezoom,workarounds,staticswitcher,resize,fade,unitymtgrabhandles,scale,session,unityshell]
CompositorRunning: None
Date: Thu Jan 12 07:42:25 2012
DistUpgraded: Log time: 2011-07-13 10:07:59.371965
DistroCodename: oneiric
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, whatever it takes to get this fixed in Ubuntu
GraphicsCard:
ATI Technologies Inc Broadway PRO [Mobility Radeon HD 5800 Series] [1002:68a1] (prog-if 00 [VGA controller])
Subsystem: Hewlett-Packard Company Device [103c:1522]InstallationMedia: Ubuntu 10.04 "Lucid Lynx" - Release Candidate amd64 (20100419.1)
MachineType: Hewlett-Packard HP ENVY 15 Notebook PC
ProcEnviron:
PATH=(custom, user)
LANG=en_US.UTF-8ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.0.0-15-generic root=UUID=639dc488-e095-42a4-8c1f-ffb1a9299e1c ro crashkernel=384M-2G:64M,2G-:128M quiet splash vt.handoff=7SourcePackage: xorg
UpgradeStatus: Upgraded to oneiric on 2011-07-13 (182 days ago)
dmi.bios.date: 04/23/2010
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: F.26
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: 1522
dmi.board.vendor: Hewlett-Packard
dmi.board.version: 36.34
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnHewlett-Packard:bvrF.26:bd04/23/2010:svnHewlett-Packard:pnHPENVY15NotebookPC:pvr048F110000241920001530000:rvnHewlett-Packard:rn1522:rvr36.34:cvnHewlett-Packard:ct10:cvrN/A:
dmi.product.name: HP ENVY 15 Notebook PC
dmi.product.version: 048F110000241920001530000
dmi.sys.vendor: Hewlett-Packard
version.compiz: compiz 1:0.9.6+bzr20110929-0ubuntu6
version.ia32-libs: ia32-libs 20090808ubuntu26
version.libdrm2: libdrm2 2.4.26-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 7.11-0ubuntu3
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 7.11-0ubuntu3
version.xserver-xorg: xserver-xorg 1:7.6+7ubuntu7
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.6.0-1ubuntu13
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.99~git20110811.g93fc084-0ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.15.901-1ubuntu2.1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20110411+8378443-1
Comment 1 Bryce Harrington 2012-01-13 06:50:09 UTC 
Created attachment 55541 [details]
BootDmesg.txt
Comment 2 Bryce Harrington 2012-01-13 06:50:57 UTC 
Created attachment 55542 [details]
CurrentDmesg.txt
Comment 3 Bryce Harrington 2012-01-13 06:51:27 UTC 
Created attachment 55543 [details]
XorgLog.txt
Comment 4 Alex Deucher 2012-01-13 08:25:54 UTC 
The problem is the modeline from your monitor for the 1920x1080 mode is greater than 165 Mhz which is the current cut off for single link mode in the driver:
(II) RADEON(0): Modeline "1920x1080"x60.0  172.78  1920 2040 2248 2576  1080 1081 1084 1118 -hsync +vsync (67.1 kHz)

It should work if you specify a modeline with a lower clock  E.g.,
Modeline "1920x1080R"  138.50  1920 1968 2000 2080  1080 1083 1088 1111 +hsync -vsync
Comment 5 Alex Deucher 2012-01-13 08:34:21 UTC 
Created attachment 55557 [details] [review]
possible fix

This patch against drm-next or Linus git should fix the issue.
Comment 6 thejoe 2012-01-13 08:53:54 UTC 
confirmed that the following sequence displays a non-garbled 1920x1080 display on the external monitor:

# xrandr --newmode "1920x1080R"  138.50  1920 1968 2000 2080  1080 1083 1088 1111 +hsync -vsync
# xrandr --addmode HDMI-0 1920x1080R
# xrandr 1920x1080R
Comment 7 Florian Mickler 2012-02-01 13:09:58 UTC 
A patch referencing this bug report has been merged in Linux v3.3-rc2:

commit 9aa59993e226af94088adaee993eb8cfd33ae295
Author: Alex Deucher <alexander.deucher@amd.com>
Date:   Fri Jan 20 15:03:30 2012 -0500

    drm/radeon/kms: refine TMDS dual link checks
Comment 8 thejoe 2012-03-07 14:45:11 UTC 
I've tested against a kernel with this patch, as well as mainline kernel (both built by ubuntu kernel team), and am still seeing the same behavior.  So seems like this change doesn't fix the issue.
Comment 9 Alex Deucher 2012-03-07 16:03:51 UTC 
Created attachment 58148 [details] [review]
fix

This patch should fix it.  Your chip is limited to 165 Mhz single link tmds.  The mode you are trying to set is >165 Mhz.  With this patch applied the mode should be properly rejected by the driver.
Comment 10 Florian Mickler 2012-03-12 15:21:47 UTC 
A patch referencing this bug report has been merged in Linux v3.3-rc7:

commit 38aa4a568ba4c3ccba83e862a01e3e60e3b811ee
Author: Alex Deucher <alexander.deucher@amd.com>
Date:   Wed Mar 7 19:05:01 2012 -0500

    drm/radeon/kms: fix hdmi duallink checks
Comment 11 Christopher M. Penalver 2016-02-24 06:03:04 UTC 
Original reporter noted fix released in later kernel version 3.3.

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