[Bug 59113] New: Banded colors/reduced depth over Thunderbolt on Mac Mini Server 2012 (6,2)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=59113

          Priority: medium
            Bug ID: 59113
          Assignee: chris at chris-wilson.co.uk
           Summary: Banded colors/reduced depth over Thunderbolt on Mac
                    Mini Server 2012 (6,2)
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
          Severity: normal
    Classification: Unclassified
                OS: Linux (All)
          Reporter: jason.heeris at gmail.com
          Hardware: x86-64 (AMD64)
            Status: NEW
           Version: 7.7 (2011)
         Component: Driver/intel
           Product: xorg

Created attachment 72653
  --> https://bugs.freedesktop.org/attachment.cgi?id=72653&action=edit
Photo of graphics artefacts described

I'm using Ubuntu 12.10 on my Mac Mini Server 6,2. I have two Dell U2412M
(1920x1200 at 60Hz) monitors. (Full system info is below.)

I initially tried to connect one monitor over the Thunderbolt/Displayport
output. But from the moment rEFIt hands over to GRUB, the graphics look quite
poor. Gradients are rough or dithered (including the boot splash, greeter
screen and desktop background), window title bars look awful, and there a
number of other ugly artefacts (see first photo). The resolution itself,
however, is fine.

Taking a screenshot does not demonstrate the problem (it looks fine when it's
opened on another OS), but a photo shows it. Connecting a monitor to the HDMI
output (using a HDMI/DVI adapter) looks fine. Windows 7 and OSX look fine on
the same monitor using the Displayport input.

There's one other interesting thing:

  - If I boot Ubuntu with only one monitor attached via HDMI/DVI, wait until it
gets to the login screen and THEN connect a second monitor to the Thunderbolt
port, they both look fine. So it seems possible to have nice output over
Thunderbolt/DP.

  - If I boot with two monitors (connected via HDMI/DVI and Thunderbolt/DP
respectively), one looks poor and one looks fine... BUT when I disconnect the
Thunderbolt one, the OTHER (HDMI/DVI connected) monitor blanks for a second and
comes back on looking just as poor as the Thunderbolt/DP did before.

The kernel is 3.5.0-19-generic. lspci tells me I have:

00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor
Graphics Controller (rev 09)

I can't see any errors in Xorg.0.log, but I don't want to paste the whole file
here unless someone asks for it.

sudo lshw -C display gives:

  *-display               
       description: VGA compatible controller
       product: 3rd Gen Core processor Graphics Controller
       vendor: Intel Corporation
       physical id: 2
       bus info: pci at 0000:00:02.0
       version: 09
       width: 64 bits
       clock: 33MHz
       capabilities: msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:49 memory:a0000000-a03fffff memory:90000000-9fffffff
ioport:2000(size=64)

OpenGL info from glxinfo is:

OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) Ivybridge Mobile 
OpenGL version string: 3.0 Mesa 9.0.1

lsmod shows that the i915 driver is loaded.

I have attached photos of normal looking graphics and the poor looking
graphics, as well as lspci and glxinfo output, and the xorg log.

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/intel-gfx-bugs/attachments/20130107/5c22697f/attachment.html>