Re: [PATCH v3 1/4] ACPI: s2idle: Add a new ->check() callback for platform_s2idle_ops

["Limonciello, Mario" <mario.limonciello@amd.com>]

On 8/30/2022 06:39, Rafael J. Wysocki wrote:
> On Mon, Aug 29, 2022 at 6:29 PM Mario Limonciello
> <mario.limonciello@amd.com> wrote:
>>
>> On some platforms it is found that Linux more aggressively enters s2idle
>> than Windows enters Modern Standby and this uncovers some synchronization
>> issues for the platform.  To aid in debugging this class of problems in
>> the future, add support for an extra optional callback intended for
>> drivers to emit extra debugging.
>>
>> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> 
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> and I'm assuming that this is for Hans.

Thanks, and yeah I think it makes more sense for this to go through 
platform-x86.

> 
>> ---
>> v2->v3:
>>   * Rename to *check
>> v1->v2:
>>   * Add a prototype for `acpi_s2idle_enter`
>>
>>   drivers/acpi/sleep.h      |  1 +
>>   drivers/acpi/x86/s2idle.c | 14 ++++++++++++++
>>   include/linux/acpi.h      |  1 +
>>   include/linux/suspend.h   |  1 +
>>   kernel/power/suspend.c    |  3 +++
>>   5 files changed, 20 insertions(+)
>>
>> diff --git a/drivers/acpi/sleep.h b/drivers/acpi/sleep.h
>> index 7fe41ee489d6..d960a238be4e 100644
>> --- a/drivers/acpi/sleep.h
>> +++ b/drivers/acpi/sleep.h
>> @@ -18,6 +18,7 @@ static inline acpi_status acpi_set_waking_vector(u32 wakeup_address)
>>   extern int acpi_s2idle_begin(void);
>>   extern int acpi_s2idle_prepare(void);
>>   extern int acpi_s2idle_prepare_late(void);
>> +extern void acpi_s2idle_check(void);
>>   extern bool acpi_s2idle_wake(void);
>>   extern void acpi_s2idle_restore_early(void);
>>   extern void acpi_s2idle_restore(void);
>> diff --git a/drivers/acpi/x86/s2idle.c b/drivers/acpi/x86/s2idle.c
>> index f9ac12b778e6..474aa46f82f6 100644
>> --- a/drivers/acpi/x86/s2idle.c
>> +++ b/drivers/acpi/x86/s2idle.c
>> @@ -486,6 +486,19 @@ int acpi_s2idle_prepare_late(void)
>>          return 0;
>>   }
>>
>> +void acpi_s2idle_check(void)
>> +{
>> +       struct acpi_s2idle_dev_ops *handler;
>> +
>> +       if (!lps0_device_handle || sleep_no_lps0)
>> +               return;
>> +
>> +       list_for_each_entry(handler, &lps0_s2idle_devops_head, list_node) {
>> +               if (handler->check)
>> +                       handler->check();
>> +       }
>> +}
>> +
>>   void acpi_s2idle_restore_early(void)
>>   {
>>          struct acpi_s2idle_dev_ops *handler;
>> @@ -527,6 +540,7 @@ static const struct platform_s2idle_ops acpi_s2idle_ops_lps0 = {
>>          .begin = acpi_s2idle_begin,
>>          .prepare = acpi_s2idle_prepare,
>>          .prepare_late = acpi_s2idle_prepare_late,
>> +       .check = acpi_s2idle_check,
>>          .wake = acpi_s2idle_wake,
>>          .restore_early = acpi_s2idle_restore_early,
>>          .restore = acpi_s2idle_restore,
>> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
>> index 6f64b2f3dc54..acaa2ddc067d 100644
>> --- a/include/linux/acpi.h
>> +++ b/include/linux/acpi.h
>> @@ -1075,6 +1075,7 @@ acpi_status acpi_os_prepare_extended_sleep(u8 sleep_state,
>>   struct acpi_s2idle_dev_ops {
>>          struct list_head list_node;
>>          void (*prepare)(void);
>> +       void (*check)(void);
>>          void (*restore)(void);
>>   };
>>   int acpi_register_lps0_dev(struct acpi_s2idle_dev_ops *arg);
>> diff --git a/include/linux/suspend.h b/include/linux/suspend.h
>> index 70f2921e2e70..03ed42ed2c7f 100644
>> --- a/include/linux/suspend.h
>> +++ b/include/linux/suspend.h
>> @@ -191,6 +191,7 @@ struct platform_s2idle_ops {
>>          int (*begin)(void);
>>          int (*prepare)(void);
>>          int (*prepare_late)(void);
>> +       void (*check)(void);
>>          bool (*wake)(void);
>>          void (*restore_early)(void);
>>          void (*restore)(void);
>> diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
>> index 827075944d28..c6272d466e58 100644
>> --- a/kernel/power/suspend.c
>> +++ b/kernel/power/suspend.c
>> @@ -136,6 +136,9 @@ static void s2idle_loop(void)
>>                          break;
>>                  }
>>
>> +               if (s2idle_ops && s2idle_ops->check)
>> +                       s2idle_ops->check();
>> +
>>                  s2idle_enter();
>>          }
>>
>> --
>> 2.34.1
>>