From: daniel.lezcano@linaro.org (Daniel Lezcano)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 00/12] CPU idle for Armada XP
Date: Fri, 13 Sep 2013 17:19:17 +0200 [thread overview]
Message-ID: <52332CF5.8050404@linaro.org> (raw)
In-Reply-To: <871u4shj6i.fsf@linaro.org>
On 09/13/2013 04:48 PM, Kevin Hilman wrote:
> Gregory CLEMENT <gregory.clement@free-electrons.com> writes:
>
>> On 13/09/2013 13:00, Andrew Lunn wrote:
>>>
>>> On Fri, Sep 13, 2013 at 12:06:29PM +0200, Gregory CLEMENT wrote:
>>>> Hello,
>>>>
>>>> This patch set adds the CPU idle support for Armada XP and prepares
>>>> the support for Armada 370. This was based on the work of Nadav
>>>> Haklai.
>>>
>>> Hi Gregory.
>>>
>>> Kirkwood has the ability to put the DDR into self refresh mode, which
>>> is used as part of the second level idle mode. Does 370/XP have this?
>>
>> Indeed there is a self refresh bit on a DDR related register. I thought
>> this kind of feature is more likely used for suspend to ram.
>>
>> We plan to also submit the suspend to ram but not immediately.
>>
>>>
>>> For XP, with it being SMP, it would be a bit more complex, since you
>>> would not want to use it unless all CPUs were idle.
>>
>> I wonder how the others SMP ARM SoCs deal with it, I hope this time
>> there will be a framework available and we won't have to create it! ;)
>
> You shouldn't have to invent anything here.
>
> For low-power states that require all CPUs to be idle, we have "coupled"
> CPUidle states (c.f. drivers/cpuidle/coupled.) OMAP and Tegra are using
> this, but I believe Daniel wants to move away from this, so I'll let him
> elaborate.
Yes, I would not recommend to use the "coupled" idle states unless you
have a good reason to do that (eg. only CPU0 can do set the PMU).
If the board provides enough mechanisms with the PMSU, there is an
alternate, lockless, sync algorithm, which can be reused, in the ux500's
cpuidle driver (c.f. drivers/cpuidle/cpuidle-ux500.c).
Otherwise, I recommend to have a look at MCPM (c.f
drivers/cpuidle/cpuidle-big_little.c).
-- Daniel
--
<http://www.linaro.org/> Linaro.org ? Open source software for ARM SoCs
Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog
next prev parent reply other threads:[~2013-09-13 15:19 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-13 10:06 [PATCH v2 00/12] CPU idle for Armada XP Gregory CLEMENT
2013-09-13 10:06 ` [PATCH v2 01/12] ARM: PJ4B: Add cpu_suspend/cpu_resume hooks for PJ4B Gregory CLEMENT
2013-09-13 10:06 ` [PATCH v2 02/12] ARM: mvebu: ll_set_cpu_coherent no more uses the coherency address as parameter Gregory CLEMENT
2013-09-13 10:06 ` [PATCH v2 03/12] ARM: mvebu: ll_set_cpu_coherent always uses the current CPU Gregory CLEMENT
2013-09-13 10:06 ` [PATCH v2 04/12] ARM: mvebu: Remove the unused argument of set_cpu_coherent() Gregory CLEMENT
2013-09-13 10:06 ` [PATCH v2 05/12] ARM: mvebu: Make ll_set_cpu_coherent() more configurable Gregory CLEMENT
2013-09-13 10:06 ` [PATCH v2 06/12] ARM: mvebu: Low level functions to disable cache snooping Gregory CLEMENT
2013-09-13 10:06 ` [PATCH v2 07/12] ARM: mvebu: Add a new set of registers for pmsu Gregory CLEMENT
2013-09-13 10:06 ` [PATCH v2 08/12] ARM: mvebu: Allow to power down L2 cache controller in idle mode Gregory CLEMENT
2013-09-13 10:06 ` [PATCH v2 09/12] ARM: mvebu: Add the PMSU related part of the cpu idle functions Gregory CLEMENT
2013-09-13 10:06 ` [PATCH v2 10/12] ARM: mvebu: Set the start address of a CPU in a separate function Gregory CLEMENT
2013-09-13 10:06 ` [PATCH v2 11/12] cpuidle: mvebu: Add initial CPU idle support for Armada 370/XP SoC Gregory CLEMENT
2013-09-13 15:36 ` Daniel Lezcano
2013-09-15 14:34 ` Gregory CLEMENT
2013-09-15 17:31 ` Daniel Lezcano
2013-10-14 14:01 ` Gregory CLEMENT
2013-09-13 16:16 ` Lorenzo Pieralisi
2013-10-14 14:14 ` Gregory CLEMENT
2013-10-14 15:06 ` Lorenzo Pieralisi
2013-09-13 10:06 ` [PATCH v2 12/12] ARM: dts: mvebu: Add a new set of registers to the PMSU node Gregory CLEMENT
2013-09-13 11:00 ` [PATCH v2 00/12] CPU idle for Armada XP Andrew Lunn
2013-09-13 11:17 ` Gregory CLEMENT
2013-09-13 11:38 ` Andrew Lunn
2013-09-13 14:48 ` Kevin Hilman
2013-09-13 15:19 ` Daniel Lezcano [this message]
2013-10-02 17:39 ` Jason Cooper
2013-10-02 17:44 ` Gregory CLEMENT
2013-10-02 17:58 ` Jason Cooper
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=52332CF5.8050404@linaro.org \
--to=daniel.lezcano@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).