linux-kernel - Re: [PATCHv1] ACPI: processor idle: Allow playing dead in C3 state

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Date:   Tue, 28 Sep 2021 08:00:52 -0500
From:   "Gong, Richard" <richard.gong@....com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Len Brown <lenb@...nel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        lijo.lazar@....com, Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCHv1] ACPI: processor idle: Allow playing dead in C3 state

Hi Rafael,

On 9/24/2021 11:31 AM, Rafael J. Wysocki wrote:
> On Wed, Sep 22, 2021 at 3:31 PM Richard Gong <richard.gong@....com> wrote:
>> When some cores are disabled on AMD platforms, the system will no longer
>> be able to enter suspend-to-idle s0ix.
>>
>> Update to allow playing dead in C3 state so that the CPUs can enter the
>> deepest state on AMD platforms.
>>
>> BugLink: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.freedesktop.org%2Fdrm%2Famd%2F-%2Fissues%2F1708&amp;data=04%7C01%7Crichard.gong%40amd.com%7Ca5c0db9ce02b4cd0864f08d97f78d33f%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637680980065602427%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=dIO5PDjpncLFIt0aGaTrKJHYIkJm8A4YByGn1%2FsHrtM%3D&amp;reserved=0
>> Suggested-by: Mario Limonciello <mario.limonciello@....com>
>> Signed-off-by: Richard Gong <richard.gong@....com>
>> ---
>>   drivers/acpi/processor_idle.c | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
>> index f37fba9e5ba0..61d5a72d218e 100644
>> --- a/drivers/acpi/processor_idle.c
>> +++ b/drivers/acpi/processor_idle.c
>> @@ -789,7 +789,8 @@ static int acpi_processor_setup_cstates(struct acpi_processor *pr)
>>                  state->enter = acpi_idle_enter;
>>
>>                  state->flags = 0;
>> -               if (cx->type == ACPI_STATE_C1 || cx->type == ACPI_STATE_C2) {
>> +               if (cx->type == ACPI_STATE_C1 || cx->type == ACPI_STATE_C2
>> +                       || cx->type == ACPI_STATE_C3) {
>>                          state->enter_dead = acpi_idle_play_dead;
>>                          drv->safe_state_index = count;
>>                  }
>> --
> Tentatively applied as 5.16 material, but have you done any research
> on why this restriction has been there in the first place?

Yes, we need this change to align with the updated firmware on AMD 
platforms.

Regards,

Richard