[coreboot] Patch merged into coreboot/master: 94998c4 lynxpoint: Add cbfs_load_payload() implementation

[gerrit at coreboot.org]

the following patch was just integrated into master:
commit 94998c4d3fa1c9f1f0aaf3623a070e8c7e364f8b
Author: Aaron Durbin <adurbin at chromium.org>
Date:   Tue Jan 22 13:54:12 2013 -0600

    lynxpoint: Add cbfs_load_payload() implementation
    
    SPI accesses can be slow depending on the setup and the access pattern.
    The current SPI hardware setup to cache and prefetch. The alternative
    cbfs_load_payload() function takes advantage of the caching in the CPU
    because the ROM is cached as write protected as well as the SPI's
    hardware's caching/prefetching implementation. The CPU will fetch
    consecutive aligned cachelines which will hit the ROM as
    cacheline-aligned addresses. Once the payload is mirrored into RAM the
    segment loading can take place by reading RAM instead of ROM.
    
    With the alternative cbfs_load_payload() the boot time on a baskingridge
    board saves ~100ms. This savings is observed using cbmem.py after
    performing warm reboots and looking at TS_SELFBOOT_JUMP (99) entries.
    This is booting with a depthcharge payload whose payload file fits
    within the SMM_DEFAULT_SIZE (0x10000 bytes).
    
    Datapoints with TS_LOAD_PAYLOAD (90) & TS_SELFBOOT_JUMP (99) cbmem entries:
    
    Baseline                          Alt
    --------                          --------
    90:3,859,310  (473)               90:3,863,647  (454)
    99:3,989,578  (130,268)           99:3,888,709  (25,062)
    
    90:3,899,450  (477)               90:3,860,926  (463)
    99:4,029,459  (130,008)           99:3,890,583  (29,657)
    
    90:3,834,600  (466)               90:3,890,564  (465)
    99:3,964,535  (129,934)           99:3,920,213  (29,649)
    
    Booted baskingridge many times and observed 100ms reduction in
    TS_SELFBOOT_JUMP times (time to load payload).
    
    Change-Id: I27b2dec59ecd469a4906b4179b39928e9201db81
    Signed-off-by: Aaron Durbin <adurbin at chromium.org>
    Reviewed-on: http://review.coreboot.org/2783
    Tested-by: build bot (Jenkins)
    Reviewed-by: Stefan Reinauer <stefan.reinauer at coreboot.org>

Build-Tested: build bot (Jenkins) at Tue Mar 19 19:14:14 2013, giving +1
Reviewed-By: Stefan Reinauer <stefan.reinauer at coreboot.org> at Tue Mar 19 20:21:49 2013, giving +2
See http://review.coreboot.org/2783 for details.

-gerrit