High Interrupt Latency in Hikey960

Hello Everyone,
We are using SPI interface and GPIO pin for interrupt. Using pin no 23 on 40 pin connector for gpio interrupt. We observed interrupt latency between 30 to 250 uS. We are using setup as mentioned below. Why we are getting this much higher latency.?

I am using Hikey 960 board for that I have cloned AOSP from below link and build using below mentioned commands.
repo init -u https://android.googlesource.com/platform/manifest -b master
repo sync -j24
. ./build/envsetup.sh
lunch hikey960-userdebug
make -j4
And used hikey-linaro kernel 4.14.
git clone https://android.googlesource.com/kernel/hikey-linaro

How to you register your interrupt handler? how do you estimate the latency?