[Bug 39696] New: dual head: different vert refresh freq, applications sync to the wrong one

[bugzilla-daemon@freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=39696

           Summary: dual head: different vert refresh freq, applications
                    sync to the wrong one
           Product: DRI
           Version: unspecified
          Platform: Other
        OS/Version: All
            Status: NEW
          Severity: major
          Priority: medium
         Component: DRM/Radeon
        AssignedTo: dri-devel@lists.freedesktop.org
        ReportedBy: klaus.kusche@computerix.info


I've a notebook with a JUNIPER 0x1002:0x68A0 chip, using KMS, dri and gallium.

I mostly use external monitors connected by display port, HDMI or DVI,
cloning the internal display onto them (identical resolution, identical
screen).

No matter what monitor (I tried two different Dell, an Iiyama and an Acer) and 
what port (DVI, HDMI, DP) I use, 
KMS always sets sligthly different vertical refresh frequencies: 
The internal display runs at 60 Hz, the external monitor runs at 59.9 Hz.

However, although I only look at the external monitor, all applications
(both 3D/DRM and video/Xv) sync to the vert refresh of the internal display.

This results in very nasty tearing effects: 
A clearly visible horizontal offset line moves up slowly on the external
monitor 
for any video or 3D application (cyclically with a period of about 10 seconds).

1.) Is there a way to run both displays at exactly the same vert frequency
and with synchronized vertical retrace?
2.) Is there a way to switch 3D and video application sync
from the internal to the external vsync rate?

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