root@phyCORE-PXA270:~ modprobe pca953x
i2c: error: exhausted retries
i2c: msg_num: 0 msg_idx: -2000 msg_ptr: 0
i2c: ICR: 000007e0 ISR: 00000002
i2c: log: [00000446:000007e0]
pca953x 0-0041: failed reading register
pca953x: probe of 0-0041 failed with error -5