linux-kernel - Re: [PATCH 1/2] ARM: cpuidle: fix !cpuidle

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Date:	Wed, 30 Mar 2016 16:17:45 +0800
From:	Jisheng Zhang <jszhang@...vell.com>
To:	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Catalin Marinas <Catalin.Marinas@....com>
CC:	<linux@....linux.org.uk>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] ARM: cpuidle: fix !cpuidle_ops[cpu].init case
 during init

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?

Thanks for reviewing,
Jisheng