From: santosh.shilimkar@ti•com (Santosh Shilimkar)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 08/16] ARM: bL_platsmp.c: make sure the GIC interface of a dying CPU is disabled
Date: Sun, 13 Jan 2013 10:07:38 +0530 [thread overview]
Message-ID: <50F23A12.9010405@ti.com> (raw)
In-Reply-To: <alpine.LFD.2.02.1301121134390.6300@xanadu.home>
On Saturday 12 January 2013 10:17 PM, Nicolas Pitre wrote:
> On Sat, 12 Jan 2013, Santosh Shilimkar wrote:
>
>> On Saturday 12 January 2013 12:37 AM, Nicolas Pitre wrote:
>>> 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@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.
>>>
>> I understood that part. What I was saying is, with CPU IF disabled and
>> if CPU doesn't enter into the intended low power state and if the wakeup
>> mechanism on that CPU is SGI/SPI, CPU may never wakeup and can lead to
>> dead lock. I have seen this scenario on OMAP especially in CPUidle path.
>
> Obviously, on the CPU idle path, you should not turn off the GIC
> interface as this might lose the ability to wake the CPU up with a
> pending interrupt, if your system is so configured.
>
> Here this is the CPU hot unplug path and we don't want the CPU to be
> awaken at all until we explicitly do something to wake it back up.
>
I see.
> However, in theory, all interrupts should have been migrated away from
> this CPU, so there shouldn't be any need for this. I should revisit the
> test that led me to create this patch.
>
Thats right from hot-plug path and SPI are concerned. But SGI/PPI can
still wakeup CPU and there is no migration as such since they are local
to that
>> It may not be relevant for switcher considering, you almost force CPU to
>> enter to low power state :-)
>
> The switcher doesn't use cpu_die() but calls into bL_cpu_power_down()
> directly.
>
Good to know that.
Regards,
Santosh
next prev parent reply other threads:[~2013-01-13 4:37 UTC|newest]
Thread overview: 132+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-10 0:20 [PATCH 00/16] big.LITTLE low-level CPU and cluster power management Nicolas Pitre
2013-01-10 0:20 ` [PATCH 01/16] ARM: b.L: secondary kernel entry code Nicolas Pitre
2013-01-10 7:12 ` Stephen Boyd
2013-01-10 15:30 ` Nicolas Pitre
2013-01-10 15:34 ` Catalin Marinas
2013-01-10 16:47 ` Nicolas Pitre
2013-01-11 11:45 ` Catalin Marinas
2013-01-11 12:05 ` Lorenzo Pieralisi
2013-01-11 12:19 ` Dave Martin
2013-01-10 23:05 ` Will Deacon
2013-01-11 1:26 ` Nicolas Pitre
2013-01-11 10:55 ` Will Deacon
2013-01-11 11:35 ` Dave Martin
2013-01-11 17:16 ` Santosh Shilimkar
2013-01-11 18:10 ` Nicolas Pitre
2013-01-11 18:30 ` Santosh Shilimkar
2013-03-07 7:37 ` Pavel Machek
2013-03-07 8:57 ` Nicolas Pitre
2013-01-10 0:20 ` [PATCH 02/16] ARM: b.L: introduce the CPU/cluster power API Nicolas Pitre
2013-01-10 23:08 ` Will Deacon
2013-01-11 2:30 ` Nicolas Pitre
2013-01-11 10:58 ` Will Deacon
2013-01-11 11:29 ` Dave Martin
2013-01-11 17:26 ` Santosh Shilimkar
2013-01-11 18:33 ` Nicolas Pitre
2013-01-11 18:41 ` Santosh Shilimkar
2013-01-11 19:54 ` Nicolas Pitre
2013-01-10 0:20 ` [PATCH 03/16] ARM: b.L: introduce helpers for platform coherency exit/setup Nicolas Pitre
2013-01-10 12:01 ` Dave Martin
2013-01-10 19:04 ` Nicolas Pitre
2013-01-11 11:30 ` Dave Martin
2013-01-10 16:53 ` Catalin Marinas
2013-01-10 17:59 ` Nicolas Pitre
2013-01-10 21:50 ` Catalin Marinas
2013-01-10 22:31 ` Nicolas Pitre
2013-01-11 10:36 ` Dave Martin
2013-01-10 22:32 ` Nicolas Pitre
2013-01-10 23:13 ` Will Deacon
2013-01-11 1:50 ` Nicolas Pitre
2013-01-11 11:09 ` Dave Martin
2013-01-11 17:46 ` Santosh Shilimkar
2013-01-11 18:07 ` Dave Martin
2013-01-11 18:34 ` Santosh Shilimkar
2013-01-14 17:08 ` Dave Martin
2013-01-14 17:15 ` Catalin Marinas
2013-01-14 18:10 ` Dave Martin
2013-01-14 21:34 ` Catalin Marinas
2013-01-10 0:20 ` [PATCH 04/16] ARM: b.L: Add baremetal voting mutexes Nicolas Pitre
2013-01-10 23:18 ` Will Deacon
2013-01-11 3:15 ` Nicolas Pitre
2013-01-11 11:03 ` Will Deacon
2013-01-11 16:57 ` Dave Martin
2013-01-10 0:20 ` [PATCH 05/16] ARM: bL_head: vlock-based first man election Nicolas Pitre
2013-01-10 0:20 ` [PATCH 06/16] ARM: b.L: generic SMP secondary bringup and hotplug support Nicolas Pitre
2013-01-11 18:02 ` Santosh Shilimkar
2013-01-14 18:05 ` Achin Gupta
2013-01-15 6:32 ` Santosh Shilimkar
2013-01-15 11:18 ` Achin Gupta
2013-01-15 11:26 ` Santosh Shilimkar
2013-01-15 18:53 ` Dave Martin
2013-01-14 16:35 ` Will Deacon
2013-01-14 16:51 ` Nicolas Pitre
2013-01-15 19:09 ` Dave Martin
2013-01-10 0:20 ` [PATCH 07/16] ARM: bL_platsmp.c: close the kernel entry gate before hot-unplugging a CPU Nicolas Pitre
2013-01-14 16:37 ` Will Deacon
2013-01-14 16:53 ` Nicolas Pitre
2013-01-14 17:00 ` Will Deacon
2013-01-14 17:11 ` Catalin Marinas
2013-01-14 17:15 ` Nicolas Pitre
2013-01-14 17:23 ` Will Deacon
2013-01-14 18:26 ` Russell King - ARM Linux
2013-01-14 18:49 ` Nicolas Pitre
2013-01-15 18:40 ` Dave Martin
2013-01-16 16:06 ` Catalin Marinas
2013-01-10 0:20 ` [PATCH 08/16] ARM: bL_platsmp.c: make sure the GIC interface of a dying CPU is disabled Nicolas Pitre
2013-01-11 18:07 ` Santosh Shilimkar
2013-01-11 19:07 ` Nicolas Pitre
2013-01-12 6:50 ` Santosh Shilimkar
2013-01-12 16:47 ` Nicolas Pitre
2013-01-13 4:37 ` Santosh Shilimkar [this message]
2013-01-14 17:53 ` Lorenzo Pieralisi
2013-01-14 16:39 ` Will Deacon
2013-01-14 16:54 ` Nicolas Pitre
2013-01-14 17:02 ` Will Deacon
2013-01-14 17:18 ` Nicolas Pitre
2013-01-14 17:24 ` Will Deacon
2013-01-14 17:56 ` Lorenzo Pieralisi
2013-01-10 0:20 ` [PATCH 09/16] ARM: vexpress: Select the correct SMP operations at run-time Nicolas Pitre
2013-01-10 0:20 ` [PATCH 10/16] ARM: vexpress: introduce DCSCB support Nicolas Pitre
2013-01-11 18:12 ` Santosh Shilimkar
2013-01-11 19:13 ` Nicolas Pitre
2013-01-12 6:52 ` Santosh Shilimkar
2013-01-10 0:20 ` [PATCH 11/16] ARM: vexpress/dcscb: add CPU use counts to the power up/down API implementation Nicolas Pitre
2013-01-10 0:20 ` [PATCH 12/16] ARM: vexpress/dcscb: do not hardcode number of CPUs per cluster Nicolas Pitre
2013-01-10 0:20 ` [PATCH 13/16] drivers: misc: add ARM CCI support Nicolas Pitre
2013-01-11 18:20 ` Santosh Shilimkar
2013-01-11 19:22 ` Nicolas Pitre
2013-01-12 6:53 ` Santosh Shilimkar
2013-01-15 18:34 ` Dave Martin
2013-01-10 0:20 ` [PATCH 14/16] ARM: TC2: ensure powerdown-time data is flushed from cache Nicolas Pitre
2013-01-10 18:50 ` Dave Martin
2013-01-10 19:13 ` Nicolas Pitre
2013-01-11 11:38 ` Dave Martin
2013-01-10 0:20 ` [PATCH 15/16] ARM: vexpress/dcscb: handle platform coherency exit/setup and CCI Nicolas Pitre
2013-01-10 12:05 ` Dave Martin
2013-01-11 18:27 ` Santosh Shilimkar
2013-01-11 19:28 ` Nicolas Pitre
2013-01-12 7:21 ` Santosh Shilimkar
2013-01-14 12:25 ` Lorenzo Pieralisi
2013-01-15 6:23 ` Santosh Shilimkar
2013-01-15 18:20 ` Dave Martin
2013-01-16 6:33 ` Santosh Shilimkar
2013-01-16 10:03 ` Lorenzo Pieralisi
2013-01-16 10:12 ` Santosh Shilimkar
2013-01-10 0:20 ` [PATCH 16/16] ARM: vexpress/dcscb: probe via device tree Nicolas Pitre
2013-01-10 0:46 ` [PATCH 00/16] big.LITTLE low-level CPU and cluster power management Rob Herring
2013-01-10 5:04 ` Nicolas Pitre
2013-01-10 23:01 ` Will Deacon
2013-01-14 9:56 ` Joseph Lo
2013-01-14 14:05 ` Nicolas Pitre
2013-01-15 2:44 ` Joseph Lo
2013-01-15 16:44 ` Nicolas Pitre
2013-01-16 16:02 ` Catalin Marinas
2013-01-16 21:18 ` Nicolas Pitre
2013-01-17 17:55 ` Catalin Marinas
2013-01-15 18:31 ` Dave Martin
2013-03-07 8:27 ` Pavel Machek
2013-03-07 9:12 ` Nicolas Pitre
2013-03-07 9:40 ` Pavel Machek
2013-03-07 9:56 ` Nicolas Pitre
2013-03-07 14:51 ` Pavel Machek
2013-03-07 15:42 ` Nicolas Pitre
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