Messages in this thread | | | Date | Mon, 17 Feb 2014 14:29:53 +0530 | From | "Srivatsa S. Bhat" <> | Subject | Re: [PATCH 2/2] cpufreq: don't call cpufreq_update_policy() on CPU addition |
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On 02/17/2014 02:24 PM, Viresh Kumar wrote: > On 17 February 2014 14:13, Srivatsa S. Bhat > <srivatsa.bhat@linux.vnet.ibm.com> wrote: >> On 02/14/2014 04:30 PM, Viresh Kumar wrote: >>> cpufreq_update_policy() is called from two places currently. From a workqueue >>> handled queued from cpufreq_bp_resume() for boot CPU and from >>> cpufreq_cpu_callback() whenever a CPU is added. >>> >>> The first one makes sure that boot CPU is running on the frequency present in >>> policy->cpu. But we don't really need a call from cpufreq_cpu_callback(), >>> because we always call cpufreq_driver->init() (which will set policy->cur >>> correctly) whenever first CPU of any policy is added back. And so every policy >>> structure is guaranteed to have the right frequency in policy->cur. >>> >> >> This wording is slightly inaccurate. ->init() may or may not set policy->cur >> (for example, powernowk8 driver doesn't set it in the init routine).. > > Its not the wording that is wrong but this particular driver then :) > This is what Documentation/cpu-drivers.txt says: > > 1.2 Per-CPU Initialization > Then, the driver must fill in the following values: > > policy->cur The current operating frequency of > this CPU (if appropriate) > > And so it is supposed to do it. >
Ah, I see.
>> But we set it for sure in __cpufreq_add_dev(): >> >> 1117 if (cpufreq_driver->get) { >> 1118 policy->cur = cpufreq_driver->get(policy->cpu); >> 1119 if (!policy->cur) { >> 1120 pr_err("%s: ->get() failed\n", __func__); >> 1121 goto err_get_freq; >> 1122 } >> 1123 } > > Its just about removing that from drivers and doing it once in core :) >
Ok..
Regards, Srivatsa S. Bhat
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