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
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