MCP23017 GPIO Interrupt Handling (RPi) - linux

Question

I have connected a MCP23017 I2C GPIO Expander chip to RPi. I use the this device driver and the mcp23017.dtbo overlay file.
I am trying to check the interrupt handling with the gpio pins. I did the following to connect the pins to interrupt(496 is the base which is GPA0 of MCP23017):
echo "496" > /sys/class/gpio/export
echo "both" > /sys/class/gpio/gpio496/edge
and then to trigger:
cat gpio496/value
But when i check /proc/interrupts it always shows 0 interrupts:
root#raspberrypi:/sys/class/gpio# cat /proc/interrupts
CPU0 CPU1 CPU2 CPU3
16: 0 0 0 0 bcm2836-timer 0 Edge arch_timer
17: 41827 52799 8260 86838 bcm2836-timer 1 Edge arch_timer
23: 67 0 0 0 ARMCTRL-level 1 Edge 3f00b880.mailbox
24: 248 0 0 0 ARMCTRL-level 2 Edge VCHIQ doorbell
46: 0 0 0 0 ARMCTRL-level 48 Edge bcm2708_fb dma
48: 4125 0 0 0 ARMCTRL-level 50 Edge DMA IRQ
50: 0 0 0 0 ARMCTRL-level 52 Edge DMA IRQ
62: 415706 0 0 0 ARMCTRL-level 64 Edge dwc_otg, dwc_otg_pcd, dwc_otg_hcd:usb1
79: 0 0 0 0 ARMCTRL-level 81 Edge 3f200000.gpio:bank0
80: 0 0 0 0 ARMCTRL-level 82 Edge 3f200000.gpio:bank1
83: 945 0 0 0 ARMCTRL-level 85 Edge 3f804000.i2c
86: 502 0 0 0 ARMCTRL-level 88 Edge mmc0
87: 5032 0 0 0 ARMCTRL-level 89 Edge uart-pl011
92: 6828 0 0 0 ARMCTRL-level 94 Edge mmc1
170: 0 0 0 0 pinctrl-bcm2835 4 Edge 1-0020, 1-0021, 1-0022, 1-0023
220: 0 0 0 0 gpio-mcp23xxx 0 Edge gpiolib
Also, when the overlay is loaded, the probe funtion is called and i get the following message:
genirq: irq 170 uses trigger mode 8; requested 2
I could not figure out the problem. I am not sure if there is something wrong in the overlay file. Below is the .dts overlay file:
// Definitions for MCP23017 Gpio Extender from Microchip Semiconductor
/dts-v1/;
/plugin/;
/ {
compatible = "brcm,bcm2835", "brcm,bcm2708", "brcm,bcm2709";
fragment#0 {
target = <&i2c1>;
__overlay__ {
status = "okay";
};
};
fragment#1 {
target = <&gpio>;
__overlay__ {
mcp23017_pins: mcp23017_pins {
brcm,pins = <4>;
brcm,function = <0>;
};
};
};
fragment#2 {
target = <&i2c1>;
__overlay__ {
#address-cells = <1>;
#size-cells = <0>;
mcp20:mcp23017#20 {
compatible = "microchip,mcp23017";
reg = <0x20>;
gpio-controller;
#gpio-cells = <2>;
interrupt-parent = <&gpio>;
interrupts = <4 2>;
interrupt-controller;
#interrupt-cells=<2>;
microchip,irq-mirror;
status = "okay";
};
};
};
__overrides__ {
gpiopin = <&mcp23017_pins>,"brcm,pins:0",
<&mcp20>,"interrupts:0";
addr = <&mcp20>,"reg:0";
};
};