From mboxrd@z Thu Jan 1 00:00:00 1970 From: nicolas.pitre@linaro.org (Nicolas Pitre) Date: Fri, 11 Jan 2013 14:07:57 -0500 (EST) Subject: [PATCH 08/16] ARM: bL_platsmp.c: make sure the GIC interface of a dying CPU is disabled In-Reply-To: <50F054E7.9000004@ti.com> References: <1357777251-13541-1-git-send-email-nicolas.pitre@linaro.org> <1357777251-13541-9-git-send-email-nicolas.pitre@linaro.org> <50F054E7.9000004@ti.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 > > --- > > 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