lynxpoint me: add support for mbp clear wait in finalize step

The management engine is slow, requiring at least 500ms between
when the Dram Init Done message is sent (right after memory training)
to when the MBP will report that it is successfully cleared and
that the ME can finally be sent the EOP message.

Currently this is adding 100-150ms to the boot time.  If we defer
waiting for the MBP Clear indicator until the finalize step we
can gain back that lost time.

boot on falco with SMI debugging enabled to
ensure that the ME is locked down in the finalize step:

Finalizing Coreboot
SMI# #0
SMI_STS: PM1 APM
ME: MBP cleared
ME: mkhi_end_of_post
ME: END OF POST message successful (0)

Change-Id: Icab4c8c8e00eea67bed5e8154d91a1eb48a492d1
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/62633
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/4375
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/southbridge/intel/lynxpoint/Kconfig b/src/southbridge/intel/lynxpoint/Kconfig
index 3cf9ffe1e5..28ebdb6c2f 100644
--- a/src/southbridge/intel/lynxpoint/Kconfig
+++ b/src/southbridge/intel/lynxpoint/Kconfig
@@ -67,4 +67,13 @@ config IFD_BIN_PATH
 	string "Path to intel firmware descriptor"
 	default "3rdparty/mainboard/$(MAINBOARDDIR)/descriptor.bin"
 
+config ME_MBP_CLEAR_LATE
+	bool "Defer wait for ME MBP Cleared"
+	default y
+	help
+	  If you set this option to y, the Management Engine driver
+	  will defer waiting for the MBP Cleared indicator until the
+	  finalize step.  This can speed up boot time if the ME takes
+	  a long time to indicate this status.
+
 endif