tree 9d788363c37f6ffc10a42ea2b9d11c80767b9d15
parent 3dadbb9c209d90c66edcef75bd5bc7352fed8da7
author Yidi Lin <yidilin@chromium.org> 1705388921 +0800
committer Felix Held <felix-coreboot@felixheld.de> 1705502460 +0000

soc/mediatek: Add EARLY_MMU_INIT kconfig option

Accessing RAM before mmu initialized is time consuming. During mmu
initialization, `mmu_init()` and `mmu_config_range()` write logs to the
console buffer and contribue the extra boot time.

This patch adds a kconfig option to move `mtk_mmu_init()` to
`bootblock_soc_early_init()`. When `EARLY_MMU_INIT` is enabled, mmu is
initialized before `console_init()` ready. So `mmu_init()` and
`mmu_config_range()` won't write logs to the console buffer and save the
boot time.

It saves about 65ms on Geralt with EARLY_MMU_INIT enabled.

Before:
   0:1st timestamp                                     239,841 (0)
  11:start of bootblock                                239,920 (79)
  12:end of bootblock                                  323,191 (83,271)

After:
   0:1st timestamp                                     239,804 (0)
  11:start of bootblock                                239,884 (80)
  12:end of bootblock                                  258,846 (18,962)

BUG=b:320381143
TEST=check timestamps in cbmem

Change-Id: I7f4c3c6c836f7276119698c6de362794cf4222a6
Signed-off-by: Yidi Lin <yidilin@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79990
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>