tree 2d94b47d189c125c2e52de779bb8c0a694538e6a
parent 77c4d6165dcb0be7164b22ae57861a0d0ce7df4c
author Kapil Porwal <kapilporwal@google.com> 1668574157 +0530
committer Eric Lai <eric_lai@quanta.corp-partner.google.com> 1669268706 +0000

soc/intel/meteorlake: Skip setting D0I3 bit for HECI devices

This patch skips setting D0I3 bit for all HECI devices by FSP.

The learning being made from Alder Lake platform showed that the CSE
EOP cmd response time is highly nondeterministic and letting the EOP
cmd issued by FSP makes the response time even worse.

The idea being pursued during Alder Lake platform is to let FSP skip sending the EOP cmd and coreboot sends it at the last minute
(late sending of EOP) to ensure there is ample time for CSE to come
to a state where the response to the EOP is almost immediate.

There were a number of refactoring being done to ensure the EOP cmd
can be sent at the later stage.

#1: Ensure FSP is not putting those HECI devices into the D0i3. (SoC specific change)
#2: Modify the CSE related boot state based operation to allow a
proper window for sending late EOP cmd. (Common Code Specific change)

The entire refactoring helps us to save ~60ms of boot time.

Without those code change EOP sending timestamp as below:

943:after sending EOP to ME                     1,248,328(61,954))

With those code change EOP sending timestamp as below:

943:after sending EOP to ME                     1,231,660 (2,754)

Port of commit d6da4ef69e4e ("soc/intel/alderlake: Skip setting D0I3
bit for HECI devices") to incorporate the #1 which is a SoC specific
code change.

BUG=none
TEST=FSP-S UPD dump suggested `DisableD0I3SettingForHeci` UPD is
set to `1`.

Excerpt from google/rex coreboot log:
[SPEW ]   DisableD0I3SettingForHeci : 0x1

Signed-off-by: Kapil Porwal <kapilporwal@google.com>
Change-Id: I1c3765ce41f192ab5f5ff176e0a2b49b312d18d2
Reviewed-on: https://review.coreboot.org/c/coreboot/+/69680
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>