[meta-freescale] imx6q gpu performance lower than expected

[Nikita Yushchenko]

Following up myself.

We have tested master + qt 5.3.2 and master + qt 5.4.1 combinations, with LVDS 1280x800 screen and eglfs backend.

Overall results are:
  dizzy, qt 5.3.2, imx6s => 22 fps  [this is poor hw, included just for reference]
  dizzy, qt 5.3.2, imx6q => 37 fps
  master, qt 5.3.2, imx6q => 49 fps
  master, qt 5.4.1, imx6q => 59 fps

Thus "memory bandwidth" is *not* the limiting factor on original setup.
Pure software update resulted into significant fps improvement.

Many thanks to Heikki Sarkanen for information that master branch shows better graphics performance.

> Hi
> 
> I've built freescale community bsp dizzy for a custom imx6q based board,
> and now I'm experimenting with GPU performance under Qt5.
> 
> I have both xcb and eglfs backends running (under different builds).
> 
> However performance is lower than was expected: on LVDS 1280x800,
> Qt5_CinematicExperience shows about 35-37 FPS, both under X11 and under
> eglfs. If using smaller window under X11, FPS increases, if using
> 1920x1080 it goes down to 20.
> 
> This is much smaller than people get [1].
> 
> [1] https://community.freescale.com/thread/305066
> 
> CPU in both cases (x11 and egl) is almost unloaded (30% of one core
> under eglfs, 30+30 under X11) so looks like speed limiting comes from GPU.
> 
> What could be reason for this?  Any hints?
> 
> 
> TIA,
> Nikita Yushchenko
>