I've tested coreboot/util/intelmetool on dell r730( haswell) and asus p10s-m ws( skylake) but got the same results:
./intelmetool -m MEI found: [8086:8d3a] C610/X99 series chipset MEI Controller #1
ME Status : 0x700f0345 ME Status 2 : 0xb8006000
ME: FW Partition Table : OK ME: Bringup Loader Failure : NO ME: Firmware Init Complete : YES ME: Manufacturing Mode : NO ME: Boot Options Present : NO ME: Update In Progress : NO ME: Current Working State : Normal ME: Current Operation State : M0 without UMA ME: Current Operation Mode : (null) ME: Error Code : No Error ME: Progress Phase : Global reset after an error ME: Power Management Event : Sx/M3->S0/M0 ME: Progress Phase State : Unknown 0x00
ME: Extend Register not valid
ME: circular buffer full, resetting... ME: message (4) too large for buffer (255) ME: GET FW VERSION message failed
host.buffer_depth and host.buffer_write_ptr having the same values( 0xff) caused it into dark. Seems SPS and ME has some differences here. Any idea how to fix it?