tree d714a6c39be7644e43fb674d47d8174f636784aa
parent ffa5ff84702684af7496ce8ad962e0f1c8b060cd
author Subrata Banik <subratabanik@google.com> 1673862280 +0530
committer Subrata Banik <subratabanik@google.com> 1674042697 +0000

soc/intel/elkhartlake: Fix incorrect `prev_sleep_state` issue

The patch fixes indication of incorrect `prev_sleep_state` on the next
boot after global reset trigger. The existing code misses an important check about `if PCH doesn't set the WAK_STS` while checking power
failure. As a result, every early warm/global reset is considered
as power failure after looking into the PMC MMIO CON-A register
alone (as ignoring the ACPI PM_CTRL.WAK_STS bit).

As per the code comment this code logic is expected to check the power
failure reason if PCH doesn't set the WAK_STS while waking from G3
state.

Without this patch:

Observation: Resuming after a warm reset is considered as
`prev_sleep_state 5` although the SLP_TYP is zero and WAK_STS bit
is set.

    pm1_sts: 8100 pm1_en: 0000 pm1_cnt: 00000000
    GEN_PMCON: d1215238 00002200
    ....
    prev_sleep_state 5

With this patch:

Observation: Resuming after a warm reset is considered as
`prev_sleep_state 0`. It matches with the SLP_TYP is zero and
WAK_STS bit is set.

    pm1_sts: 8100 pm1_en: 0000 pm1_cnt: 00000000
    GEN_PMCON: d1215238 00002200
    ....
    prev_sleep_state 0


Signed-off-by: Subrata Banik <subratabanik@google.com>
Change-Id: Ib43d3402f94f47dc576fb99a6b2a7acf6f0af220
Reviewed-on: https://review.coreboot.org/c/coreboot/+/71982
Reviewed-by: Lean Sheng Tan <sheng.tan@9elements.com>
Reviewed-by: Sean Rhodes <sean@starlabs.systems>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>