[PATCH v4 08/10] powerpc/powernv: Add platform support for stop instruction
Shreyas B Prabhu
shreyas at linux.vnet.ibm.com
Tue May 31 02:24:04 AEST 2016
On 05/28/2016 05:36 AM, Ram Pai wrote:
> On Tue, May 24, 2016 at 06:45:12PM +0530, Shreyas B. Prabhu wrote:
>> @@ -230,11 +236,18 @@ static DEVICE_ATTR(fastsleep_workaround_applyonce, 0600,
>> + * First deep stop state. Used to figure out when to save/restore
>> + * hypervisor context.
>> + */
>> +u64 pnv_first_deep_stop_state;
> maybe this has to be intialized to some correct default value?
> It there a gaurantee that OPAL_PM_STOP_INST_FAST is set only when
> CPU_FTR_ARCH_300 is supported?
Stop instruction is newly introduced in POWER ISA v3.0. So it is
guaranteed that OPAL_PM_STOP_INST_FAST is set only when CPU_FTR_ARCH_300
is supported. So the scenario you've described below will not arise.
> if cpu_has_feature(CPU_FTR_ARCH_300) is not true, than
> pnv_first_deep_stop_state will be not be initialized.
> And if supported_cpuidle_states
> has OPAL_PM_STOP_INST_FAST flag set, than power_stop0 is called which
> will blindly use pnv_first_deep_stop_state thinking it is initialized to
> something sane.
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