[PATCH 3/3] arm64: psci: Add support to call cpu_suspend with deepest C state.

[amit daniel kachhap]

On Thu, Oct 30, 2014 at 4:16 PM, Lorenzo Pieralisi
<lorenzo.pieralisi at arm.com> wrote:
> On Thu, Oct 30, 2014 at 03:55:38AM +0000, Amit Daniel Kachhap wrote:
>> This feature will be useful for system suspend/resume which may
>> intend to invoke cpu_suspend with deepest possible C state level.
>
> We are working on defining system states in the PSCI specification,
> but it is not set in stone yet (Cc'ed Charles).
>
> I guess you are posting this code because you have already an
> implementation that supports system suspend/resume, so I am
> taking an immediate action to come up with an API suitable
> for that asap.
Yes that would be useful. Thanks
>
> On a side note I do not necessarily like this magic idle index
> logic, I prefer adding an API for that, that translates the call
> into whatever is required by the back-end (ie PSCI) implementation.
yeah this is a kind of workaround and API will be better.
>
> Thanks,
> Lorenzo
>
>> Signed-off-by: Amit Daniel Kachhap <amit.daniel at samsung.com>
>> ---
>>  arch/arm64/include/asm/psci.h | 2 ++
>>  arch/arm64/kernel/psci.c      | 8 ++++++++
>>  2 files changed, 10 insertions(+)
>>
>> diff --git a/arch/arm64/include/asm/psci.h b/arch/arm64/include/asm/psci.h
>> index e5312ea..487e52b 100644
>> --- a/arch/arm64/include/asm/psci.h
>> +++ b/arch/arm64/include/asm/psci.h
>> @@ -14,6 +14,8 @@
>>  #ifndef __ASM_PSCI_H
>>  #define __ASM_PSCI_H
>>
>> +#define CPU_PSCI_IDLE_INDEX_MAX              0xff
>> +
>>  int psci_init(void);
>>
>>  #endif /* __ASM_PSCI_H */
>> diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
>> index 4ebc146..a761513 100644
>> --- a/arch/arm64/kernel/psci.c
>> +++ b/arch/arm64/kernel/psci.c
>> @@ -70,6 +70,7 @@ enum psci_function {
>>  static DEFINE_PER_CPU_READ_MOSTLY(struct psci_power_state *, psci_power_state);
>>
>>  static u32 psci_function_id[PSCI_FN_MAX];
>> +static u32 cpu_psci_idle_state_count;
>>
>>  static int psci_to_linux_errno(int errno)
>>  {
>> @@ -239,6 +240,8 @@ static int __maybe_unused cpu_psci_cpu_init_idle(struct device_node *cpu_node,
>>       if (!count)
>>               return -ENODEV;
>>
>> +     cpu_psci_idle_state_count = count;
>> +
>>       psci_states = kcalloc(count, sizeof(*psci_states), GFP_KERNEL);
>>       if (!psci_states)
>>               return -ENOMEM;
>> @@ -521,6 +524,11 @@ static int __maybe_unused cpu_psci_cpu_suspend(unsigned long index)
>>  {
>>       int ret;
>>       struct psci_power_state *state = __get_cpu_var(psci_power_state);
>> +
>> +     /* Check and select the deepest idle state */
>> +     if (index == CPU_PSCI_IDLE_INDEX_MAX)
>> +             index = cpu_psci_idle_state_count;
>> +
>>       /*
>>        * idle state index 0 corresponds to wfi, should never be called
>>        * from the cpu_suspend operations.
>> --
>> 1.9.1
>>
>>
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