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

[Lorenzo Pieralisi]

On Mon, Dec 01, 2014 at 08:08:55AM +0000, amit daniel kachhap wrote:
> 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.
> Hi Lorenzo,
> 
> Any update on this API for system sleep.

Hi Amit,

Sorry for the delay in replying, I am working on it at the moment, we will
post the API in the coming weeks.

Thank you,
Lorenzo

> 
> Regards,
> Amit
> 
> >
> > 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.
> >
> > 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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