As I understand, each GPIO port with 32 GPIO pins should have one IRQ, right?
UC3B should have two GPIO ports, so it's AVR32_GPIO_IRQ_0 and AVR32_GPIO_IRQ_1 that are used, right?
then how about AVR32_GPIO_IRQ_3, AVR32_GPIO_IRQ_4 and AVR32_GPIO_IRQ_5?
are they not used by anything?