On Mon, Nov 07, 2011 at 12:50:24PM -0600, Scott Wood wrote:
> 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
Yes. They can be changed independently.
I will set ppc_proc_freq inside the lock.
-chenhui
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