acpi-cpufreq: Add comment under ACPI_ADR_SPACE_SYSTEM_IO case
policy->cur is now set by cpufreq core when cpufreq_driver->get() is defined and so drivers aren't required to set it. When space_id is ACPI_ADR_SPACE_SYSTEM_IO for acpi cpufreq driver it doesn't set ->get to a valid function pointer and so policy->cur is required to be set by driver. This is already followed in acpi-cpufreq driver. This patch adds a comment describing why we need to set policy->cur from driver. Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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@ -837,7 +837,12 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
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switch (perf->control_register.space_id) {
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case ACPI_ADR_SPACE_SYSTEM_IO:
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/* Current speed is unknown and not detectable by IO port */
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/*
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* The core will not set policy->cur, because
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* cpufreq_driver->get is NULL, so we need to set it here.
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* However, we have to guess it, because the current speed is
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* unknown and not detectable via IO ports.
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*/
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policy->cur = acpi_cpufreq_guess_freq(data, policy->cpu);
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break;
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case ACPI_ADR_SPACE_FIXED_HARDWARE:
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