Created attachment 121469 [details] Xorg.0.log at 6db906ea8188cd7f731e5ef7391115ee8f5c17c8, With UXA on my Lenovo Thinkpad T530 Ivy Bridge machine, playing video with mpv (https://github.com/mpv-player/mpv) worked fine keeping up with my 60hz LVDS or HDMI TV using the command mpv file.mkv --no-config --fs --vo=opengl:scale=spline36 --video-sync=display-vdrop --osd-msg1='${estimated-display-fps}' This is the bare minimum opengl output driver with a mid-quality spline36 luma scaler implemented as an opengl shader. The added "--video-sync=display-vdrop --osd-msg1='${estimated-display-fps}' " activates display sync and displays the effective framerate on the screen. At d909c460743a0cabc5c0ed30e063e99af7b26b17, it seems that vsyncs start to happen about twice as fast ~120fps on the 60hz displays. Then, three commits later at 6db906ea8188cd7f731e5ef7391115ee8f5c17c8, it appears that I am no longer able to render frames fast enough for the refresh rate so that it bounces around 50 +/- 5 fps on either display. The problem goes away if I remove the scale=spline36 scaler so that it falls back to cheaper bilinear, which is why I say this is a performance regression. Similarly, the hardly taxing GLXgears appears to render ~60fps just fine. The problem also does not appear to exist for SNA, but I am unable to use that mode due to other problems (#91066).
Created attachment 121470 [details] dmesg with drm.debug=0x06 mpv is playing stuttery video between 18.237840 and 21.528853
I should add that I am using Linux 4.4.0
This no longer seems to be a problem using with Driver "intel" to load the debian packaged xserver-xorg-video-intel=2.99.917+git20161105-1+b1. (linux-4.10, mpv git-b60817f9dd).
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