From: Daniel Lezcano <daniel.lezcano@linaro.org>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: lenb@kernel.org, linux-pm@vger.kernel.org,
linux-acpi@vger.kernel.org, patches@linaro.org,
linaro-dev@lists.linaro.org, pdeschrijver@nvidia.com,
lorenzo.pieralisi@arm.com
Subject: Re: [PATCH 3/6] acpi : remove pointless cpuidle device state_count init
Date: Sun, 16 Sep 2012 22:38:49 +0200 [thread overview]
Message-ID: <505638D9.80302@linaro.org> (raw)
In-Reply-To: <201209072350.50389.rjw@sisk.pl>
On 09/07/2012 11:50 PM, Rafael J. Wysocki wrote:
> On Friday, September 07, 2012, Daniel Lezcano wrote:
>> The cpuidle core takes care of filling this field from drv->state_count.
>
> I'm not quite sure this is always valid. If dev has already been
> initialized and dev->state_count is different from 0,
> cpuidle_enable_device() doesn't actually change it.
>
> Have you considered all of the possible scenarios?
Ok, there is the scenario where the ACPI supports _CST.
At runtime, ACPI may notify the OS a C-state changed for a specific cpu
and this is done through 'acpi_processor_cst_has_changed' followed by
'acpi_processor_setup_cpuidle_cx'.
So at the end, we could have different cpus with one cpu with less
C-states than the other, if I understood correctly ACPIspec30.pdf =>
page 262 :)
In conclusion, we should keep this variable filled from there and keep
this in mind in cpuidle.c in order to not break acpi in the future.
Maybe a comment in cpuidle.c would help ... especially with a single
C-state registration.
>> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>> ---
>> drivers/acpi/processor_idle.c | 2 --
>> 1 files changed, 0 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
>> index 084b1d2..fc4757e 100644
>> --- a/drivers/acpi/processor_idle.c
>> +++ b/drivers/acpi/processor_idle.c
>> @@ -1035,8 +1035,6 @@ static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr)
>> break;
>> }
>>
>> - dev->state_count = count;
>> -
>> if (!count)
>> return -EINVAL;
>>
>>
>
--
<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
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2012-09-16 20:38 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-07 10:19 [PATCH 0/6] cpuidle : per cpu latencies Daniel Lezcano
2012-09-07 10:19 ` [PATCH 1/6] acpi : move the acpi_idle_driver variable declaration Daniel Lezcano
2012-09-07 21:19 ` Rafael J. Wysocki
2012-09-11 11:14 ` Daniel Lezcano
2012-09-11 20:28 ` Rafael J. Wysocki
2012-09-07 10:19 ` [PATCH 2/6] acpi : move cpuidle_device field out of the acpi_processor_power structure Daniel Lezcano
2012-09-07 11:03 ` Amit Kucheria
2012-09-07 21:40 ` Rafael J. Wysocki
2012-09-07 21:54 ` Rafael J. Wysocki
2012-09-07 22:06 ` Rafael J. Wysocki
2012-09-11 12:20 ` Daniel Lezcano
2012-09-11 20:32 ` Rafael J. Wysocki
2012-09-07 10:19 ` [PATCH 3/6] acpi : remove pointless cpuidle device state_count init Daniel Lezcano
2012-09-07 11:01 ` Amit Kucheria
2012-09-07 21:50 ` Rafael J. Wysocki
2012-09-16 20:38 ` Daniel Lezcano [this message]
[not found] ` <505638D9.80302-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2012-09-16 21:02 ` Rafael J. Wysocki
2012-09-07 10:19 ` [PATCH 4/6] cpuidle : add a pointer for cpuidle_state in the cpuidle_device Daniel Lezcano
[not found] ` <1347013172-12465-1-git-send-email-daniel.lezcano-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2012-09-07 10:19 ` [PATCH 5/6] cpuidle : use per cpuidle device cpu states Daniel Lezcano
2012-09-07 10:19 ` [PATCH 6/6] cpuidle : add cpuidle_register_states function Daniel Lezcano
2012-09-07 11:04 ` [PATCH 0/6] cpuidle : per cpu latencies Amit Kucheria
2012-09-07 12:02 ` Daniel Lezcano
2012-09-07 22:17 ` Rafael J. Wysocki
2012-09-17 8:03 ` Daniel Lezcano
2012-09-17 20:50 ` Rafael J. Wysocki
2012-09-17 21:35 ` Daniel Lezcano
2012-09-18 9:52 ` Lorenzo Pieralisi
2012-09-18 21:10 ` Rafael J. Wysocki
2012-09-18 11:19 ` Peter De Schrijver
2012-09-18 21:05 ` Rafael J. Wysocki
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=505638D9.80302@linaro.org \
--to=daniel.lezcano@linaro.org \
--cc=lenb@kernel.org \
--cc=linaro-dev@lists.linaro.org \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=lorenzo.pieralisi@arm.com \
--cc=patches@linaro.org \
--cc=pdeschrijver@nvidia.com \
--cc=rjw@sisk.pl \
/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).