From: Scott Wood <scottwood@freescale•com>
To: Zhao Chenhui <chenhui.zhao@freescale•com>
Cc: Jerry Huang <Chang-Ming.Huang@freescale•com>,
linuxppc-dev@lists•ozlabs.org
Subject: Re: [PATCH 4/7] powerpc/85xx: add support to JOG feature using cpufreq interface
Date: Mon, 7 Nov 2011 12:50:24 -0600 [thread overview]
Message-ID: <4EB82870.1090907@freescale.com> (raw)
In-Reply-To: <20111107102724.GA16470@localhost.localdomain>
On 11/07/2011 04:27 AM, Zhao Chenhui wrote:
> On Fri, Nov 04, 2011 at 02:42:54PM -0500, Scott Wood wrote:
>> On 11/04/2011 07:36 AM, Zhao Chenhui wrote:
>>> + cpufreq_frequency_table_target(policy,
>>> + mpc85xx_freqs,
>>> + target_freq,
>>> + relation,
>>> + &new);
>>> +
>>> + freqs.old = policy->cur;
>>> + freqs.new = mpc85xx_freqs[new].frequency;
>>> + freqs.cpu = policy->cpu;
>>> +
>>> + mutex_lock(&mpc85xx_switch_mutex);
>>> + cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
>>> +
>>> + pr_info("Setting frequency for core %d to %d kHz, " \
>>> + "PLL ratio is %d/2\n",
>>> + policy->cpu,
>>> + mpc85xx_freqs[new].frequency,
>>> + mpc85xx_freqs[new].index);
>>> +
>>> + set_pll(mpc85xx_freqs[new].index, policy->cpu);
>>> +
>>> + cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
>>> + mutex_unlock(&mpc85xx_switch_mutex);
>>> +
>>> + ppc_proc_freq = freqs.new * 1000ul;
>>
>> ppc_proc_freq is global -- can CPUs not have their frequencies adjusted
>> separately?
>>
>> It should be under the lock, if the lock is needed at all.
>>
>
> There is only one ppc_proc_freq. no lock.
I realize there's only one.
I'm asking whether CPUs can have their frequencies set indpendently --
if the answer is no, and this function is not specific to a CPU, my only
concern is the lock. Either this function can be called multiple times
in parallel, in which case the ppc_proc_freq update should be inside the
lock, or it can't, in which case why do we need the lock at all?
-Scott
next prev parent reply other threads:[~2011-11-07 18:50 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-04 12:36 [PATCH 4/7] powerpc/85xx: add support to JOG feature using cpufreq interface Zhao Chenhui
2011-11-04 19:42 ` Scott Wood
2011-11-07 10:27 ` Zhao Chenhui
2011-11-07 18:50 ` Scott Wood [this message]
2011-11-09 11:38 ` Zhao Chenhui
2011-11-09 16:13 ` Scott Wood
-- strict thread matches above, loose matches on Subject: below --
2010-12-03 12:34 [PATCH 1/7] powerpc/85xx: re-enable timebase sync disabled by KEXEC patch Li Yang
2010-12-03 12:34 ` [PATCH 2/7] powerpc/85xx: add HOTPLUG_CPU support Li Yang
2010-12-03 12:34 ` [PATCH 3/7] powerpc/85xx: add the deep sleep support Li Yang
2010-12-03 12:34 ` [PATCH 4/7] powerpc/85xx: add support to JOG feature using cpufreq interface Li Yang
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=4EB82870.1090907@freescale.com \
--to=scottwood@freescale$(echo .)com \
--cc=Chang-Ming.Huang@freescale$(echo .)com \
--cc=chenhui.zhao@freescale$(echo .)com \
--cc=linuxppc-dev@lists$(echo .)ozlabs.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
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