Re: [PATCH 1/2] ARM: cpuidle: fix !cpuidle_ops[cpu].init case during init

[Daniel Lezcano]

On 03/30/2016 10:43 AM, Jisheng Zhang wrote:
> On Wed, 30 Mar 2016 10:41:09 +0200 Daniel Lezcano wrote:
>
> > On 03/30/2016 10:17 AM, Jisheng Zhang wrote:
> > > On Wed, 30 Mar 2016 10:09:12 +0200 Daniel Lezcano wrote:
> > >
> > > > On 03/30/2016 09:16 AM, Jisheng Zhang wrote:
> > > > > Hi Daniel,
> > > >
> > > > [ ... ]
> > > >
> > > > Added Lorenzo and Catalin.
> > > >
> > > > > > Hi Jisheng,
> > > > > >
> > > > > > this should be handled in the arm_cpuidle_read_ops function.
> > > > >
> > > > > Thanks for reviewing. After some consideration, I think this patch isn't correct
> > > > > There may be platforms which doesn't need the init member at all, although
> > > > > currently I don't see such platforms in mainline, So I'll drop this patch
> > > > > and send out one v2 only does the optimization.
> > > >
> > > > There is an inconsistency between ARM and ARM64. The 'cpu_get_ops', the
> > > > arm_cpuidle_read_ops from the ARM64 side, returns -EOPNOTSUPP when the
> > > > init function is not there for cpuidle.
> > >
> > > yes.
> > > arm64's arm_cpuidle_init() returns -EOPNOTSUPP if init callback isn't defined
> > >
> > > > I don't think it is a problem, but as ARM/ARM64 are sharing the same
> > > > cpuidle-arm.c driver it would make sense to unify the behavior between
> > > > both archs.
> > >
> > > yes, agree with you. From "unify" point of view, could I move back the suspend
> > > callback check and init callback check into arm_cpuidle_init() for arm as V1 does?
> >
> > Why ? To be consistent with ARM64 ?
>
> Yes, that's my intention.

Well, I don't have a strong opinion on that. ARM64 cpu_ops is slightly 
different from cpuidle_ops as the cpu boot / hotplug operations are 
placed in a different place and that explains why on ARM64 we can have 
an successful 'get_ops' because we use the partially filled structure. 
On ARM, it is cpuidle_ops only, so we can gracefully fail if the ops are 
not defined.

IMO, it still make sense to keep the checks in arm_cpuidle_read_ops for ARM.


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