linux-kernel - Re: [RESEND PATCH] acpi-cpufreq: get the cur_freq from acpi_processor

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Date:	Tue, 30 Sep 2014 15:09:45 +0800
From:	Wang Weidong <wangweidong1@...wei.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
CC:	<viresh.kumar@...aro.org>, <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org >> \"linux-kernel@...r.kernel.org\"" 
	<linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH] acpi-cpufreq: get the cur_freq from acpi_processor_performance
 states

On 2014/9/28 4:01, Rafael J. Wysocki wrote:
> On Saturday, September 27, 2014 01:32:59 PM Wang Weidong wrote:
>> On 2014/9/27 7:21, Rafael J. Wysocki wrote:
>>> On Thursday, August 21, 2014 01:55:15 PM Wang Weidong wrote:
>>>> As the initialized freq_tables maybe different from the p-states
>>>> values, so the array index is different as well.
>>>>
>>>> p-states value: [2400 2400 2000 ...], while the freq_tables:
>>>> [2400 2000 ... CPUFREQ_TABLE_END]. After setted the freqs 2000,
>>>> the perf->state is 3 while the freqs_table's index should be 2.
>>>> So when call the get_cur_freq_on_cpu, the freqs value we get
>>>> is 2400.
>>>>
>>>> So, fix the problem with the correct tables.
>>>
>>> What you're saying is basically that freq_table and perf->states
>>> diverge at one point.  Shouldn't we re-generate freq_table in that
>>> case instead of fixing up get_cur_freq_on_cpu() only in a quite
>>> indirect way? 
>>>
>> Hi Rafael,
>>
>> Thanks for your reply.
>>
>> You mean that we should re-generate the freq_table in that case?
>> Could we fix the table init like this:
>>
>> --- a/drivers/cpufreq/acpi-cpufreq.c
>> +++ b/drivers/cpufreq/acpi-cpufreq.c
>> @@ -779,7 +779,7 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
>>
>>         /* table init */
>>         for (i = 0; i < perf->state_count; i++) {
>> -               if (i > 0 && perf->states[i].core_frequency >=
>> +               if (i > 0 && perf->states[i].core_frequency >
>>                     data->freq_table[valid_states-1].frequency / 1000)
>>                         continue;
>>
>> when the value is same, we just keep the value into the freq_table.
> 
> That would only be OK if it is guaranteed that the set of available
> states hasn't changed, which I'm not sure is the case.
> 
> Rafael
> 

Yep, ACPI maybe will dynamic to report the states to the OS . So I should consider it again.

Regards,
Wang
> 
> .
> 


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