BayTrail SoC - PUnit writes

Bay Trail -I SoC which has 30679 D0 Stepping Processor

Microcode Versions tried

M0F30679_90A

M0130679_903

MSR 79 – writes microcode to SoC (Passed)

MSR 8b – Reads microcode revision (Passed)

Hang at below code

; For A-step, bits 0 and 1 need to be set after patch load and before MRC (first possible reset)

;Without setting BIOS_RESET_DONE on A0, Bios will stuck at vlvdxe after GT PowerManagement

; Could be done later in flow for B-step, but no need to move and have it in 2 places.

;

;Program BIOS_RESET_DONE (bit0) and BIOS_ALL_DONE (bit1) in PUNIT.BIOS_RESET_CPL, Port 0x4, Offset 0x5

;BIOS_ALL_DONE is newly added bit for B0.

mov edx, 0CF8h ;config MCD

mov eax, 800000d4h

out dx, eax

;

mov edx, 0CFCh ;set Bit0 and Bit1

mov eax, 3

out dx, eax

mov edx, 0CF8h ;config MCR

mov eax, 800000d0h

out dx, eax

mov edx, 0CFCh ;write_opcode+portID+offset

mov eax, 007040510h

out dx, eax

why there is a Hang at this register write? when i remove this code , boot goes ahead and hangs at GT Power Management.when i disable both, Graphics does not come up