IRQ handler not called by ARM A53

I'm testing GIC and ARM A53 connectivity. I can see that GIC is forwarding the IRQ request and ARM core has received it(shows in ISR reg). However, my IRQ handler is not getting called. Here is how I'm registering it..

void main () { 
... 
__enable_irq();
 ... 
}
 __irq void irqHandler(void) { 
printf("Hello from the IRQ handler\n"); 
... 
}