--- zzzz-none-000/linux-3.10.107/Documentation/cpu-freq/core.txt 2017-06-27 09:49:32.000000000 +0000 +++ scorpion-7490-727/linux-3.10.107/Documentation/cpu-freq/core.txt 2021-02-04 17:41:59.000000000 +0000 @@ -20,6 +20,7 @@ --------- 1. CPUFreq core and interfaces 2. CPUFreq notifiers +3. CPUFreq Table Generation with Operating Performance Point (OPP) 1. General Information ======================= @@ -54,16 +55,13 @@ ---------------------------- These are notified when a new policy is intended to be set. Each -CPUFreq policy notifier is called three times for a policy transition: +CPUFreq policy notifier is called twice for a policy transition: 1.) During CPUFREQ_ADJUST all CPUFreq notifiers may change the limit if they see a need for this - may it be thermal considerations or hardware limitations. -2.) During CPUFREQ_INCOMPATIBLE only changes may be done in order to avoid - hardware failure. - -3.) And during CPUFREQ_NOTIFY all notifiers are informed of the new policy +2.) And during CPUFREQ_NOTIFY all notifiers are informed of the new policy - if two hardware drivers failed to agree on a new policy before this stage, the incompatible hardware shall be shut down, and the user informed of this. @@ -93,6 +91,30 @@ old - old frequency new - new frequency -If the cpufreq core detects the frequency has changed while the system -was suspended, these notifiers are called with CPUFREQ_RESUMECHANGE as -second argument. +3. CPUFreq Table Generation with Operating Performance Point (OPP) +================================================================== +For details about OPP, see Documentation/power/opp.txt + +dev_pm_opp_init_cpufreq_table - cpufreq framework typically is initialized with + cpufreq_frequency_table_cpuinfo which is provided with the list of + frequencies that are available for operation. This function provides + a ready to use conversion routine to translate the OPP layer's internal + information about the available frequencies into a format readily + providable to cpufreq. + + WARNING: Do not use this function in interrupt context. + + Example: + soc_pm_init() + { + /* Do things */ + r = dev_pm_opp_init_cpufreq_table(dev, &freq_table); + if (!r) + cpufreq_frequency_table_cpuinfo(policy, freq_table); + /* Do other things */ + } + + NOTE: This function is available only if CONFIG_CPU_FREQ is enabled in + addition to CONFIG_PM_OPP. + +dev_pm_opp_free_cpufreq_table - Free up the table allocated by dev_pm_opp_init_cpufreq_table