iMX6ULL, Linux 4.1.15, how to use EPIT to implement accurate periodic interrupts?

[JanieZee]

I want to use EPIT to achieve an interrupt every 156us, but actual tests have found that the interrupt interval is not precisely 156us, with some intervals even reaching the millisecond level.

Why is this happening? What should I do to achieve an accurate 156us periodic interrupt?

Thanks

[Zhiming_Liu]

How do you call the epit function in your test? Have you write EPIT driver by yourself?

[JanieZee]

Yes, this is the EPIT driver. Additionally, I have set CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE=y, but the interrupt interval is still not accurate.

[Zhiming_Liu · Accepted solution]

Hi @JanieZee 

There are two ways to use epit:

1.Use arch/arm/mach-imx/epit.c

https://github.com/nxp-imx/linux-imx/blob/imx_4.1.15_2.0.0_ga/arch/arm/mach-imx/epit.c

2.Use mainline commit

https://www.mail-archive.com/search?l=linux-kernel@vger.kernel.org&q=subject:%22%5C%5BPATCH+v6+4%5C%...

[bighero77]

for the first method. the code is here. but would not been build
how can I make this file build?
thanks.
https://github.com/nxp-imx/linux-imx/blob/imx_4.1.15_2.0.0_ga/arch/arm/mach-imx/epit.c