RTL8201 BMCR problem

I have got problems with Realtek RTL8201 chip on ARM system.

In some cases works correctly.
Other cases (exactly same program!) runs but refuses connection.
Sometimes it depends on translation (side effects - eg. a new dummy 
variable exists or not) and program shows true effect only after HW 
reset (i.e: without reset it works like previous version).
So: wrong version is wrong, right version is right after HW reset -
all 2 versions work like previous reseted version if it loaded with SW 
reset.

The all difference is the behaviour of MII_BMCR: it is 2100h and un-writable 
on false case and works correctly on normal case.