linux-kernel - Re: [PATCH] ACPI: x86: Adjust Microsoft LPS0

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Date:   Thu, 1 Jun 2023 23:17:59 -0500
From:   "Limonciello, Mario" <mario.limonciello@....com>
To:     david.e.box@...ux.intel.com, rafael@...nel.org
Cc:     linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH] ACPI: x86: Adjust Microsoft LPS0 _DSM handling sequence


On 6/1/2023 10:06 PM, David E. Box wrote:
> On Thu, 2023-06-01 at 20:46 -0500, Limonciello, Mario wrote:
>> On 6/1/2023 8:31 PM, David E. Box wrote:
>>> On Thu, 2023-06-01 at 18:39 -0500, Mario Limonciello wrote:
>>>> In Windows the Microsoft _DSM doesn't call functions 3->5->7 for suspend
>>>> and 8->6->4 for resume like Linux currently does.
>>>>
>>>> Rather it calls 3->7->5 for suspend and 6->8->4 for resume.
>>>> Align this calling order for Linux as well.
>>>>
>>>> Link:
>>>> https://learn.microsoft.com/en-us/windows-hardware/design/device-experiences/modern-standby-states
>>> I didn't catch the ordering in the link.
>> Yeah it's tough to interpret from the link, because the picture at the
>> bottom
>> is missing annotations.
>>
>> Basically if you look at the picture the blue part is the screen on/off.
>>
>> The green part is "modern standby" and then the little "humps" are LPS0
>> enter/exit.
>>
>>> Was there any issue that prompted this
>>> change?
>>
>> We were debugging an unrelated problem and noticed the difference
>> comparing the
>>
>> BIOS debugging log from Windows and Linux.
>>
>> If an OEM depends on this call order in that code used in LPS0 phase
>> requires
>> changes from MS phase I could hypothesize this fixes it.
>>
>>
>>> David
>> BTW - is there interest in supporting the Microsoft _DSM GUID for Intel
>> side too?
>>
>> It's an incongruity today that we run both AMD GUID and Microsoft GUID
>> for AMD systems
>> but only run Intel GUID for Intel systems.
> There hasn't been a need yet. Rafael have you look at it?
>
> David

AFAICT from Linux side it should be a one line patch to drop:

         lps0_dsm_func_mask_microsoft = -EINVAL;

>>>> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
>>>> ---
>>>>    drivers/acpi/x86/s2idle.c | 14 +++++++-------
>>>>    1 file changed, 7 insertions(+), 7 deletions(-)
>>>>
>>>> diff --git a/drivers/acpi/x86/s2idle.c b/drivers/acpi/x86/s2idle.c
>>>> index e499c60c4579..7214197c15a0 100644
>>>> --- a/drivers/acpi/x86/s2idle.c
>>>> +++ b/drivers/acpi/x86/s2idle.c
>>>> @@ -485,11 +485,11 @@ int acpi_s2idle_prepare_late(void)
>>>>                                           ACPI_LPS0_ENTRY,
>>>>                                           lps0_dsm_func_mask,
>>>> lps0_dsm_guid);
>>>>           if (lps0_dsm_func_mask_microsoft > 0) {
>>>> -               acpi_sleep_run_lps0_dsm(ACPI_LPS0_ENTRY,
>>>> -                               lps0_dsm_func_mask_microsoft,
>>>> lps0_dsm_guid_microsoft);
>>>>                   /* modern standby entry */
>>>>                   acpi_sleep_run_lps0_dsm(ACPI_LPS0_MS_ENTRY,
>>>>                                   lps0_dsm_func_mask_microsoft,
>>>> lps0_dsm_guid_microsoft);
>>>> +               acpi_sleep_run_lps0_dsm(ACPI_LPS0_ENTRY,
>>>> +                               lps0_dsm_func_mask_microsoft,
>>>> lps0_dsm_guid_microsoft);
>>>>           }
>>>>    
>>>>           list_for_each_entry(handler, &lps0_s2idle_devops_head, list_node)
>>>> {
>>>> @@ -524,11 +524,6 @@ void acpi_s2idle_restore_early(void)
>>>>                   if (handler->restore)
>>>>                           handler->restore();
>>>>    
>>>> -       /* Modern standby exit */
>>>> -       if (lps0_dsm_func_mask_microsoft > 0)
>>>> -               acpi_sleep_run_lps0_dsm(ACPI_LPS0_MS_EXIT,
>>>> -                               lps0_dsm_func_mask_microsoft,
>>>> lps0_dsm_guid_microsoft);
>>>> -
>>>>           /* LPS0 exit */
>>>>           if (lps0_dsm_func_mask > 0)
>>>>                   acpi_sleep_run_lps0_dsm(acpi_s2idle_vendor_amd() ?
>>>> @@ -539,6 +534,11 @@ void acpi_s2idle_restore_early(void)
>>>>                   acpi_sleep_run_lps0_dsm(ACPI_LPS0_EXIT,
>>>>                                   lps0_dsm_func_mask_microsoft,
>>>> lps0_dsm_guid_microsoft);
>>>>    
>>>> +       /* Modern standby exit */
>>>> +       if (lps0_dsm_func_mask_microsoft > 0)
>>>> +               acpi_sleep_run_lps0_dsm(ACPI_LPS0_MS_EXIT,
>>>> +                               lps0_dsm_func_mask_microsoft,
>>>> lps0_dsm_guid_microsoft);
>>>> +
>>>>           /* Screen on */
>>>>           if (lps0_dsm_func_mask_microsoft > 0)
>>>>                   acpi_sleep_run_lps0_dsm(ACPI_LPS0_SCREEN_ON,