linux-kernel - Re: [PATCH 1/3] Powerpc: mpc85xx: refactor the PM operations

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Message-ID: <1438829848.2097.129.camel@freescale.com>
Date:	Wed, 5 Aug 2015 21:57:28 -0500
From:	Scott Wood <scottwood@...escale.com>
To:	Chenhui Zhao <chenhui.zhao@...escale.com>
CC:	<b29983@...escale.com>, <b07421@...escale.com>,
	<linux-kernel@...r.kernel.org>,
	Tang Yuantian <Yuantian.Tang@...escale.com>,
	Tang Yuantian <Yuantian.Tang@...scale.com>
Subject: Re: [PATCH 1/3] Powerpc: mpc85xx: refactor the PM operations

On Wed, 2015-08-05 at 18:11 +0800, Chenhui Zhao wrote:
> On Tue, Aug 4, 2015 at 4:26 AM, Scott Wood <scottwood@...escale.com> 
> wrote:
> > On Mon, 2015-08-03 at 19:32 +0800, Chenhui Zhao wrote:
> > >  >
> > 
> > >  On Sat, Aug 1, 2015 at 7:59 AM, Scott Wood <scottwood@...escale.com>
> > >  wrote:
> > 
> > >  >
> > >  > Could you explain irq_mask()?  Why would there still be IRQs 
> > > destined
> > >  > for
> > >  > this CPU at this point?
> > > 
> > >  This function just masks irq by setting the registers in RCPM (for
> > >  example, RCPM_CPMIMR, RCPM_CPMCIMR). Actually, all irqs to this CPU
> > >  have been migrated to other CPUs.
> > 
> > So why do we need to set those bits in RCPM?  Is it just caution?
> 
> Setting these bits can mask interrupts signalled to RCPM from MPIC as a 
> means of
> waking up from a lower power state. So, cores will not be waked up 
> unexpectedly.

Why would the MPIC be signalling those interrupts if they've been masked at 
the MPIC?

-Scott


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