[PATCH 08/16] ARM: bL_platsmp.c: make sure the GIC interface of a dying CPU is disabled

[Nicolas Pitre]

On Fri, 11 Jan 2013, Santosh Shilimkar wrote:

> On Thursday 10 January 2013 05:50 AM, Nicolas Pitre wrote:
> > Otherwise there might be some interrupts or IPIs becoming pending and the
> > CPU will not enter low power mode when doing a WFI.  The effect of this
> > is a CPU that loops back into the kernel, go through the first man
> > election, signals itself as alive,  and prevent the cluster from being
> > shut down.
> > 
> > This could benefit from a better solution.
> > 
> > Signed-off-by: Nicolas Pitre <nico at linaro.org>
> > ---
> >   arch/arm/common/bL_platsmp.c        | 1 +
> >   arch/arm/common/gic.c               | 6 ++++++
> >   arch/arm/include/asm/hardware/gic.h | 2 ++
> >   3 files changed, 9 insertions(+)
> > 
> > diff --git a/arch/arm/common/bL_platsmp.c b/arch/arm/common/bL_platsmp.c
> > index 0ae44123bf..6a3b251b97 100644
> > --- a/arch/arm/common/bL_platsmp.c
> > +++ b/arch/arm/common/bL_platsmp.c
> > @@ -68,6 +68,7 @@ static void __ref bL_cpu_die(unsigned int cpu)
> >   	pcpu = mpidr & 0xff;
> >   	pcluster = (mpidr >> 8) & 0xff;
> >   	bL_set_entry_vector(pcpu, pcluster, NULL);
> > +	gic_cpu_if_down();
> 
> So for a case where CPU still don't power down for some reason even
> after CPU interface is disabled, can not listen to and SGI or PPI.
> Not sure if this happens on big.LITTLE but i have seen one such issue
> on Cortex-A9 based SOC.

Here the problem was the reverse i.e. a CPU wouldn't go down because 
some pending SGIs prevented that.


Nicolas