linux-kernel - Re: [PATCH 5/9] powerpc/85xx: disable irq by hardware when suspend for 64-bit

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Message-ID: <1394836901.12479.125.camel@snotra.buserror.net>
Date:	Fri, 14 Mar 2014 17:41:41 -0500
From:	Scott Wood <scottwood@...escale.com>
To:	Chenhui Zhao <chenhui.zhao@...escale.com>
CC:	<linuxppc-dev@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>,
	<leoli@...escale.com>, <Jason.Jin@...escale.com>
Subject: Re: [PATCH 5/9] powerpc/85xx: disable irq by hardware when suspend
 for 64-bit

On Wed, 2014-03-12 at 15:46 +0800, Chenhui Zhao wrote:
> On Tue, Mar 11, 2014 at 06:51:20PM -0500, Scott Wood wrote:
> > On Fri, 2014-03-07 at 12:58 +0800, Chenhui Zhao wrote:
> > > In 64-bit mode, kernel just clears the irq soft-enable flag
> > > in struct paca_struct to disable external irqs. But, in
> > > the case of suspend, irqs should be disabled by hardware.
> > > Therefore, hook a function to ppc_md.suspend_disable_irqs
> > > to really disable irqs.
> > > 
> > > Signed-off-by: Chenhui Zhao <chenhui.zhao@...escale.com>
> > > ---
> > >  arch/powerpc/platforms/85xx/corenet_generic.c |   12 ++++++++++++
> > >  1 files changed, 12 insertions(+), 0 deletions(-)
> > > 
> > > diff --git a/arch/powerpc/platforms/85xx/corenet_generic.c b/arch/powerpc/platforms/85xx/corenet_generic.c
> > > index 3fdf9f3..983d81f 100644
> > > --- a/arch/powerpc/platforms/85xx/corenet_generic.c
> > > +++ b/arch/powerpc/platforms/85xx/corenet_generic.c
> > > @@ -32,6 +32,13 @@
> > >  #include <sysdev/fsl_pci.h>
> > >  #include "smp.h"
> > >  
> > > +#if defined(CONFIG_PPC64) && defined(CONFIG_SUSPEND)
> > > +static void fsl_suspend_disable_irqs(void)
> > > +{
> > > +	__hard_irq_disable();
> > > +}
> > > +#endif
> > 
> > Why the underscore version?  Don't you want PACA_IRQ_HARD_DIS to be set?
> > 
> > If hard disabling is appropriate here, shouldn't we do it in
> > generic_suspend_disable_irqs()?
> > 
> > Are there any existing platforms that supply a
> > ppc_md.suspend_disable_irqs()?  I don't see any when grepping.
> > 
> > -Scott
> 
> Will use hard_irq_disable().
> 
> I think this is a general problem for powerpc.
> Should clear MSR_EE before suspend. I agree to put it
> in generic_suspend_disable_irqs().

BTW, make sure you test this patchset with CONFIG_DEBUG_PREEMPT and
similar debugging options to help ensure that the soft IRQ state is
being tracked properly.

-Scott


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