I am trying to interface EVAL AD7190/92EBZ board by Digi-key with beaglebone black. I have enabled spi0 of beaglebone and verified with oscilloscope. As per the data-sheet of AD7190 I want to read the default values of different registers. but each read operation gives 0xff or 0x00. Is there any known issue which gives this result ? I am using the present linux device driver for ad7192. Even reading ID register results to 0xff.