Groups > linux.kernel > #1201445

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

From	Scott Wood <scottwood@freescale.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/3] Powerpc: mpc85xx: refactor the PM operations
Date	2015-08-06 07:50 +0200
Message-ID	<pUmdY-86Q-19@gated-at.bofh.it> (permalink)
References	(2 earlier) <pTmg2-1ME-5@gated-at.bofh.it> <pTuwW-5lZ-5@gated-at.bofh.it> <pUjzr-3Vy-13@gated-at.bofh.it> <pUjzr-3Vy-11@gated-at.bofh.it> <pUmdY-86Q-21@gated-at.bofh.it>
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On Thu, 2015-08-06 at 12:20 +0800, Chenhui Zhao wrote:
> On Thu, Aug 6, 2015 at 10:57 AM, Scott Wood <scottwood@freescale.com> 
> wrote:
> > On Wed, 2015-08-05 at 18:11 +0800, Chenhui Zhao wrote:
> > >  On Tue, Aug 4, 2015 at 4:26 AM, Scott Wood <scottwood@freescale.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@freescale.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
> > 
> 
> The interrupts to RCPM from MPIC are IRQ, Machine Check, NMI and 
> Critical interrupts. Some of them didn't be masked in MPIC.

What interrupt could actually happen to a sleeping cpu that this protects 
against?

-Scott

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Thread

Re: [PATCH 1/3] Powerpc: mpc85xx: refactor the PM operations Scott Wood <scottwood@freescale.com> - 2015-08-06 05:00 +0200
  Re: [PATCH 1/3] Powerpc: mpc85xx: refactor the PM operations Scott Wood <scottwood@freescale.com> - 2015-08-06 07:50 +0200
    Re: [PATCH 1/3] Powerpc: mpc85xx: refactor the PM operations Scott Wood <scottwood@freescale.com> - 2015-08-06 20:10 +0200

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