I am using this device, KSZ9897S, (
https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ProductDocuments/DataSheets/KSZ9897S-Data-Sheet-DS00002394C.pdf) and this is the errata (
https://ww1.microchip.com/downloads/aemDocuments/documents/UNG/ProductDocuments/Errata/KSZ9897S-Errata-DS80000759.pdf)
I want to disable Auto-MDIX.
Hence, I went to this register, page 127, section 5.2.2.20 PHY Auto MDI / MDI-X Register.
When I went to understand, how to write to this register, I found on page 65 of the datasheet. "For multi-byte registers, the data is addressed in a big-endian format, with the most significant byte at the lowestaddress, and the least significant byte at the highest address,"
Also, with reference to the errata document point 6, I need to write this register as 32bit along with the 5.2.2.21. register PHY Control Register.
Upon default configuration start-up, I got these values for the 5.2.2.20 & 5.2.2.21 REGISTERs - 0x2400 0000.
While I tried to decode the above register values for each bit by big endian format as they mention. But when I do so, it seems that "RESERVED" bits are having some value. But RESERVED Bits should not have any value right? Hence, I assume, I am reading it incorrectly. Please clarify.
I am not able to understand how this value is coming?
Can someone help me to understand the default registers value that I obtained above? And with the same thing, I just want to disable MDIX. Hence, what should be the change I need to do?