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About imx6qp IPU prefetch and GPU

Question asked by Zongbiao Liao on Jul 13, 2016
Latest reply on Jul 18, 2016 by Bio_TICFSL

Hello Community

 

I did the following tests with Yocto3.14.52_1.1.0.

 

1) used the original BSP(with IPU prefetch enabled for fb1)

Run /opt/viv_samples/vdk/tutorial1~tutorial7 (do GPU benchmark test).

 

2)modified the imx6qp-sabreauto.dts as bellow(disable IPU prefetch for fb1).

The original code:

&mxcfb1 {

  prefetch;

};

 

modified code:

#if 0

&mxcfb1 {

  prefetch;

};

#endif

 

then compiled imx6qp-sabreauto.dtb and run /opt/viv_samples/vdk/tutorial1~tutorial7 (do GPU benchmark test).

 

the results is as bellow:

 

The LCD display I used is 800 * 480@58Hz.

It seems that when IPU prefetch is enabled, the output fps of GPU demos is fixed to 57.54(the Vsync of LCD).

And when IPU prefetch is disabled, the output fps of GPU demos became reasonable for i.MX6QP.

 

Could you explain why does the IPU prefetch feature have effects on GPU benchmark test?

 

Thank you!

ZongbiaoLiao

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