From: swarren@wwwdotorg•org (Stephen Warren)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 0/6] ARM: tegra114: add CPU hotplug support
Date: Thu, 16 May 2013 12:19:48 -0600 [thread overview]
Message-ID: <51952344.1090003@wwwdotorg.org> (raw)
In-Reply-To: <1368698019.7403.10.camel@jlo-ubuntu-64.nvidia.com>
On 05/16/2013 03:53 AM, Joseph Lo wrote:
> On Thu, 2013-05-16 at 07:38 +0800, Stephen Warren wrote:
>> On 05/15/2013 04:27 AM, Joseph Lo wrote:
>>> Tegra 114 is different with other Tegra SoC chips. It using ARM Cortex-A15
>>> as CPU core and a enhanced flow controller for CPU power control. So
>>> we need to skip some code that was for Contex-A9 and some other support
>>> code that was for other Tegra SoC chips. Then adding the proper power up
>>> and hot plug control for Tegra114.
>>
>> This series mostly works OK, but I see one problem: I can't hotunplug
>> CPU0, which the commit descriptions and code changes imply I should be
>> able to do:
>>
>> root at localhost:~# echo 0 > /sys/devices/system/cpu/cpu0/online
>> -bash: echo: write error: Operation not permitted
>
> I want to provide this function originally. But I found the
> tegra_cpu_disable() was removed recently. It was replaced by the common
> cpu_disable() function that didn't allow CPU0 to be un-plugged.
Is there a specific reason for that; is there some problem in the core
ARM code that implies CPU0 should never be disabled?
> But I had verified the CPU0 is OK to be un-plugged on the older
> linux-next branch that tegra_cpu_disable() watn't removed yet.
>
> Do you want me to add them back to support this function for Tegra114?
If there is a problem removing CPU0 in the core code, the functionality
of this series is OK, although it's probably worth removing the parts
that attempt to make CPU0 hot-unpluggable to reduce the diff size.
If there's no problem removing CPU0, it'd be good to make it work,
although that could be done in followon patches.
next prev parent reply other threads:[~2013-05-16 18:19 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-15 10:27 [PATCH 0/6] ARM: tegra114: add CPU hotplug support Joseph Lo
2013-05-15 10:27 ` [PATCH 1/6] ARM: tegra: add an assembly marco to check Tegra SoC ID Joseph Lo
2013-05-15 22:43 ` Stephen Warren
2013-05-16 10:09 ` Joseph Lo
2013-05-16 18:21 ` Stephen Warren
2013-05-15 10:27 ` [PATCH 2/6] ARM: tegra: skip SCU and PL310 code when CPU is not Cortex-A9 Joseph Lo
2013-05-15 22:48 ` Stephen Warren
2013-05-16 10:13 ` Joseph Lo
2013-05-15 10:27 ` [PATCH 3/6] ARM: tegra: make tegra_resume can work for Tegra114 Joseph Lo
2013-05-15 22:57 ` Stephen Warren
2013-05-16 10:35 ` Joseph Lo
2013-05-16 18:24 ` Stephen Warren
2013-05-15 10:27 ` [PATCH 4/6] ARM: tegra114: add power up sequence for warm boot CPU Joseph Lo
2013-05-15 10:27 ` [PATCH 5/6] clk: tegra114: implement wait_for_reset and disable_clock for tegra_cpu_car_ops Joseph Lo
2013-05-15 23:02 ` Stephen Warren
2013-05-16 19:17 ` Mike Turquette
2013-05-15 10:27 ` [PATCH 6/6] ARM: tegra114: add CPU hotplug support Joseph Lo
2013-05-15 23:11 ` Stephen Warren
2013-05-16 11:14 ` Joseph Lo
2013-05-16 18:26 ` Stephen Warren
2013-05-15 23:38 ` [PATCH 0/6] " Stephen Warren
2013-05-16 9:53 ` Joseph Lo
2013-05-16 18:19 ` Stephen Warren [this message]
2013-05-17 10:15 ` Joseph Lo
2013-05-17 10:27 ` Russell King - ARM Linux
2013-05-17 10:23 ` Russell King - ARM Linux
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