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soc/intel/elkhartlake: Fix incorrect prev_sleep_state issue

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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>
This commit is contained in:
Subrata Banik 2023-01-16 15:14:40 +05:30
commit ea0c91fdc9
1 changed files with 1 additions and 1 deletions
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2
src/soc/intel/elkhartlake/pmutil.c
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@ -211,7 +211,7 @@ int soc_prev_sleep_state(const struct chipset_power_state *ps, int prev_sleep_st
* S5 because the PCH does not set the WAK_STS bit when waking
* from a true G3 state.
*/
if (ps->gen_pmcon_a & (PWR_FLR | SUS_PWR_FLR))
if (!(ps->pm1_sts & WAK_STS) && (ps->gen_pmcon_a & (PWR_FLR | SUS_PWR_FLR)))
prev_sleep_state = ACPI_S5;
/*