DP83869HM: Extended register set issue

Dear all!

I have an issue with reading from the DP83869 extended registers on the DP83869EVM.

I am using a custom NXP ls1046a processor board connected via SGMII and MDIO with the DP83869EVM. In u-boot I use the mii utility to read from the standard register set and the extended register set, reading from the extended registers with the method explained in the datasheet 9.4.9.1.7 section. I evaluate the module by reading from register OP_MODE_DECODE, GPIO_MUX_CTRL, BMCR, BMSR, PHYIDR1 and PHYIDR2. See the read transactions and the results below. The phy address is 0. I have set up the straps on the eval board to SGMII->COPPER.

BMCR, BMSR, PHYIDR1, PHYIDR2

=> mii read 0 0x0
001F
=> mii read 0 0x1
E3FF
=> mii read 0 0x2
0007
=> mii read 0 0x3
1CFF

OP_MODE_DECODE(it should be:0x40):

=> mii write 0 0x001f
=> mii write 0 0x0d 0x001f
=> mii write 0 0x0e 0x01df
=> mii write 0 0x0d 0x401f
=> mii read 0 0x0e
0001

GPIO_MUX_CTRL(it should be:0x417a):

=> mii write 0 0x0d 0x001f
=> mii write 0 0x0e 0x1e0
=> mii write 0 0x0d 0x401f
=> mii read 0 0x0e
0FFF

Am I misunderstanding the extended register read process?

Thanks,

Kristóf