Re: [PATCH 1/2] platform/x86/amd/pmc: Delay suspend for some Lenovo Laptops

[Mario Limonciello <superm1@kernel.org>]

> 
> Are you sure it behaves like this?
> The check is basically "is the SMU table's s0i3_last_entry_status != 0".
> And as far as I can tell this is the case after every successful suspend,
> it only seems to be reset by rebooting or if a suspend fails.
> 
> See smu_fw_info_show() (for /sys/kern/debug/amd_pmc/smu_fw_info):
> seq_printf(s, "Last S0i3 Status: %s\n", table.s0i3_last_entry_status ? "Success" :
> 		   "Unknown/Fail");
> 
> When I read /sys/kern/debug/amd_pmc/smu_fw_info right after booting, it prints
> "Last S0i3 Status: Unknown/Fail"
> After resuming, even minutes (and presumably hours) later, it prints
> "Last S0i3 Status: Success"
> indicating that s0i3_last_entry_status still is != 0.
> 
>>
>> Now you might have been confused by not looking at commit
>> 4dbd11796f3a8eb95647507befc41995458a4023.  This fixes the behavior as
>> it's supposed to be.
>>
First suspend entry:

amd_pmc_s2idle_prepare()
->amd_pmc_setup_smu_logging()
->->memset_io(dev->smu_virt_addr, 0, sizeof(struct smu_metrics))

That is the table is cleared.

amd_pmc_s2idle_check()
->get_metrics_table() && table.s0i3_last_entry_status

The table is fetched and check (last entry will be 0).
No delay.

At this point system is in hardware sleep.

If system resumes from hardware sleep table.s0i3_last_entry_status will 
be non-zero.

If you re-enter:

amd_pmc_s2idle_check() will do the msleep.

If you exit:

amd_pmc_s2idle_restore()
-> amd_pmc_validate_deepest()

This will read metrics table and tell you in logs if you didn't get to 
HW sleep.