[Bug 58843] [945 lvds downclock] Very slow redraw performance

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=58843

--- Comment #2 from Chris Wilson <chris at chris-wilson.co.uk> ---
(In reply to comment #0)
> Symptoms:
> urxvt: very slow - I can see each character being drawn onto the screen
>
> glxgears: running with vblank_mode=0, glxgears runs at about 22.5 FPS.
>
> youtube: In Firefox, playing a video with Adobe Flash, and drm.debug=0x2, I
> can see that lvds upclock does not happen for frame updates of the video -
> lvds is downclocked for continuous periods of time on the order of seconds
> (expected behavior?)

This can be expected as we have never marked the fb as busy if the scanout is
accessed via the GTT mapping (which is how the swrast in flash will eventually
be updated). 

The only thing that can be attributed to lvds downclocking here is the vblank
limited glxgears. The 2D engine should not be rate limited by the vrefresh
frequency - something else is broken.

Your dmesg and a full-debug Xorg log would be useful.

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