[XS] Change in coreboot[main]: soc/intel/{adl, mtl}: Avoid redundant display init by joining to MBUS

[Subrata Banik (Code Review)]

Subrata Banik has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/78387?usp=email )

Change subject: soc/intel/{adl, mtl}: Avoid redundant display init by joining to MBUS
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soc/intel/{adl, mtl}: Avoid redundant display init by joining to MBUS

This patch ensures that the IGD joins the MBUS when the firmware splash
screen feature is enabled (aka BMP_LOGO config is enabled).

This prevents the i915 driver from reinitializing the display, which
can save up to 75ms-80ms of boot time and eliminate a brief period of
blank screen between the firmware splash screen and the OS login
prompt.

BUG=b:284799726
TEST=Able to build and boot google/rex

Change-Id: I36af167afa902053a987602d494a8830ad9b1b1a
Signed-off-by: Subrata Banik 
---
M src/soc/intel/alderlake/Kconfig
M src/soc/intel/meteorlake/Kconfig
2 files changed, 2 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/87/78387/1

diff --git a/src/soc/intel/alderlake/Kconfig b/src/soc/intel/alderlake/Kconfig
index 4b960c1..fcd9ebb 100644
--- a/src/soc/intel/alderlake/Kconfig
+++ b/src/soc/intel/alderlake/Kconfig
@@ -82,6 +82,7 @@
    select SOC_INTEL_COMMON_RESET
    select SOC_INTEL_CSE_SEND_EOP_LATE if !BOARD_GOOGLE_BRYA_COMMON
    select SOC_INTEL_CSE_SET_EOP
+	select SOC_INTEL_GFX_MBUS_JOIN if BMP_LOGO
    select SOC_INTEL_MEM_MAPPED_PM_CONFIGURATION
    select HAVE_INTEL_COMPLIANCE_TEST_MODE
    select SSE2
diff --git a/src/soc/intel/meteorlake/Kconfig b/src/soc/intel/meteorlake/Kconfig
index 590e8b8..a8332e8 100644
--- a/src/soc/intel/meteorlake/Kconfig
+++ b/src/soc/intel/meteorlake/Kconfig
@@ -89,6 +89,7 @@
    select SOC_INTEL_CSE_SEND_EOP_LATE if !MAINBOARD_HAS_CHROMEOS
    select SOC_INTEL_CSE_SET_EOP
    select SOC_INTEL_IOE_DIE_SUPPORT
+	select SOC_INTEL_GFX_MBUS_JOIN if BMP_LOGO
    select SOC_INTEL_GFX_NON_PREFETCHABLE_MMIO
    select SOC_INTEL_MEM_MAPPED_PM_CONFIGURATION
    select SSE2