SYNCHRONIZATION FAILURE !

Hello,

I try to run PTB with AMD Radeon R9 380 "Tonga pro" on Ubuntu 16.04-LTS.

We use high refresh rate display (BenQ Zowie XL2540, 4.5" 16:9 1920 x 1080 TN 240Hz ).

and try to run it at native 240 Hz or at 120Hz.

It really does not matter, in both cases I have en error (below)

It seems that PTD can't estimate monitor refresh interval.

Any help would be very valuable!

Elena



PTB-DEBUG:PsychOSGetSwapCompletionTimestamp: Invalid return values ust = 0, msc = 0 from call with success return code (sbc = 597)! Failing with rc = -2.
PTB-DEBUG:PsychOSGetSwapCompletionTimestamp: This likely means a driver bug or malfunction, or that timestamping support has been disabled by the user in the driver!


PTB-INFO: OpenGL-Renderer is ATI Technologies Inc. :: AMD Radeon R9 200 Series :: 4.5.13462 Compatibility Profile Context 16.50.5
PTB-INFO: VBL startline = 1080 , VBL Endline = 1142
PTB-INFO: Measured monitor refresh interval from beamposition = 8.336466 ms [119.954904 Hz].
PTB-INFO: Will try to use OS-Builtin OpenML sync control support for accurate Flip timestamping.
PTB-INFO: Measured monitor refresh interval from VBLsync = 8.340742 ms [119.893408 Hz]. (582 valid samples taken, stddev=0.261973 ms.)
PTB-INFO: Reported monitor refresh interval from operating system = 8.334653 ms [119.981003 Hz].
PTB-INFO: Small deviations between reported values are normal and no reason to worry.

WARNING: Couldn't compute a reliable estimate of monitor refresh interval! Trouble with VBL syncing?!?


----- ! PTB - ERROR: SYNCHRONIZATION FAILURE ! ----


One or more internal checks (see Warnings above) indicate that synchronization
of Psychtoolbox to the vertical retrace (VBL) is not working on your setup.

This will seriously impair proper stimulus presentation and stimulus presentation timing!
Please read 'help SyncTrouble' for information about how to solve or work-around the problem.
You can force Psychtoolbox to continue, despite the severe problems, by adding the command
Screen('Preference', 'SkipSyncTests', 1); at the top of your script, if you really know what you are doing.


Error using Screen