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?