tree cd989ba3daacc7bee07638b4c81ace21b922d4e8
parent c4fbeacd01772ad297d5c508bc44e9fa3bc27fb6
author Reka Norman <rekanorman@google.com> 1663042012 +1000
committer Felix Held <felix-coreboot@felixheld.de> 1670361384 +0000

drivers/intel/fsp2_0: Update MRC cache in ramstage

Currently the MRC cache is updated in romstage, immediately after
returning from FSP-M. Since cbmem is not cached in romstage, the update
is slow (~6 ms on nissa). Specifically, the new MRC data returned by the
FSP is stored in the FSP reserved memory in cbmem, so hashing the new
data is slow.

Move the MRC cache update to ramstage, where cbmem is cached. On nissa,
this saves ~5 ms of boot time.

Before:
552:finished loading ChromeOS VPD (RW)                631,667 (16)
  3:after RAM initialization                          637,703 (6,036)
  4:end of romstage                                   650,307 (12,603)

After:
552:finished loading ChromeOS VPD (RW)                631,832 (15)
  3:after RAM initialization                          633,002 (1,169)
  4:end of romstage                                   645,582 (12,580)

In ramstage, save_mrc_data() takes ~138 us.

BUG=b:242667207
TEST=MRC caching still works as expected on nivviks - after clearing the
MRC cache, memory is retrained on the next boot, but cached data is used
on subsequent boots.

Change-Id: Ie6aa2dee83a3ab8913830746593935d36a034b8d
Signed-off-by: Reka Norman <rekanorman@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/67669
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>