linux-kernel - RE: [PATCH v4] ARM: perf: save/restore pmu registers in pm notifier

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Date:	Wed, 21 May 2014 04:46:41 -0700
From:	Neil Zhang <zhangwm@...vell.com>
To:	"'Sudeep Holla'" <sudeep.holla@....com>,
	Will Deacon <Will.Deacon@....com>
CC:	"'linux@....linux.org.uk'" <linux@....linux.org.uk>,
	"'linux-arm-kernel@...ts.infradead.org'" 
	<linux-arm-kernel@...ts.infradead.org>,
	"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
	"'devicetree@...r.kernel.org'" <devicetree@...r.kernel.org>
Subject: RE: [PATCH v4] ARM: perf: save/restore pmu registers in pm notifier

Sudeep，

> -----Original Message-----
> From: Sudeep Holla [mailto:sudeep.holla@....com]
> Sent: 2014年5月14日 17:32
> To: Neil Zhang; Will Deacon
> Cc: Sudeep Holla; 'linux@....linux.org.uk';
> 'linux-arm-kernel@...ts.infradead.org'; 'linux-kernel@...r.kernel.org';
> 'devicetree@...r.kernel.org'
> Subject: Re: [PATCH v4] ARM: perf: save/restore pmu registers in pm notifier
> 
> 
> 
> On 14/05/14 03:28, Neil Zhang wrote:
> >> -----Original Message-----
> >> From: Will Deacon [mailto:will.deacon@....com]
> >> Sent: 2014年5月14日 2:45
> >> To: Neil Zhang
> >> Cc: Sudeep Holla; 'linux@....linux.org.uk';
> >> 'linux-arm-kernel@...ts.infradead.org';
> >> 'linux-kernel@...r.kernel.org'; 'devicetree@...r.kernel.org'
> >> Subject: Re: [PATCH v4] ARM: perf: save/restore pmu registers in pm
> >> notifier
> >>
> >> On Mon, May 12, 2014 at 11:22:09AM +0100, Neil Zhang wrote:
> >>>>> The device tree bindings for power domains is under discussion [1]
> >>>>
> >>>> Thanks for the information.
> >>>> But it currently for device only, core related stuff are not supported.
> >>>> And is it really good to register power provider for core and let
> >>>> vfp / pmu etc to get it?
> >>>>
> >>>
> >>> What's your suggestion about it?
> >>> Is it OK that I add it under the PMU node?
> >>
> >> I don't really mind. I just want to avoid re-inventing the wheel in a
> >> PMU-specific way and having to maintain that code forever because it
> >> ended up in our DT description.
> >>
> >> Will
> >
> > I will prepare another patch to add DT description under PMU since
> > there is no generic power domain support for pm notifier if no other
> concerns.
> > We can change the manner if there is generic power domain support for
> pm notifier later.
> > Thanks.
> 
> No, please don't add any DT bindings for power domains specific to PMU
> node.
> We can't change the DT bindings once added.
> 
> As I pointed out the DT bindings for generic power domains are under
> discussion.
> See if you can reuse it, if not help in extending it so that it can be used.
> 

Sorry for reply later.
As I said before the under discussed generic power domain is not suitable for
CPU peripherals since they are all known belong to CPU or cluster power domain.
If we want to follow the way they are discussion, we need to register core 
and cluster power provider, and need vfp/gic/pmu etc to require them.
Is it really suitable?

> Regards,
> Sudeep
> 
> 

Best Regards,
Neil Zhang