In the I.MX257 PDK, I breaked at 0x00000000 by JTAG and read GPIO-4 register.
DR GDIR PSR ICR1
0x53F9C000: 20000000 00000000 20000000 00000000
ICR2 IMR ISR
0x53F9C010: 00000000 00000000 DFFFFFFF 00000000
0x20000000 in PSR means gpio4_GPIO is enabled in IOMUXC.
The corresponding DR bit is set, because it's default direction is input and data is sensed at the pad pin.
Now in the ISR, the 29 bit looks cleard
In Reference Manual, the default values of ISR is 0, however it looks 1 is the default/reset value.
Could you explain how to read ISR register?