sb/amd/sb700: Add option to increase SPI speed to 33MHz

Hardware / Coreboot - Timothy Pearson [raptorengineering.com] - 26 August 2016 11:22 UTC

Some SB700-based systems and ROMs support high speed (33MHz) SPI access instead of the power-on default 16.5MHz. Add an option to enable high speed SPI access in the bootblock, and set the default value to Disabled. This greatly decreases boot time on SB700-based systems, especiall when a large payload is in use.

On a KGPE-D16 with a Petitboot (Linux + initramfs) payload, the command prompt was accessible within 20 seconds of power on, which incidentally is faster than the proprietary BIOS on the same machine could even reach the GRUB bootloader.

Change-Id: Iadbd9bb611754262ef75a5e5a6ee4390a46e45cf

6e5421d sb/amd/sb700: Add option to increase SPI speed to 33MHz
src/southbridge/amd/sb700/Kconfig | 10 ++++++++++
src/southbridge/amd/sb700/bootblock.c | 34 +++++++++++++++++++++++++++++++++
2 files changed, 44 insertions(+)

Upstream: review.coreboot.org

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