On 25-05-16, 19:53, Steve Muckle wrote:
> Support the new resolve_freq cpufreq callback which resolves a target
> frequency to a driver-supported frequency without actually setting it.
And here is the first abuser of this API as I was talking about in the
earlier patch :)
But, I know why you are doing it and I think we can do it differently.
So, lets assume that the ->resolve_freq() callback will ONLY be
provided by the drivers which also provide a ->target() callback.
i.e. not by acpi-cpufreq at least.
> The target frequency and resolved frequency table entry are cached so
> that a subsequent fast_switch operation may avoid the frequency table
> walk assuming the requested target frequency is the same.
>
> Suggested-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
> Signed-off-by: Steve Muckle <smuc...@linaro.org>
> ---
> drivers/cpufreq/acpi-cpufreq.c | 56
> ++++++++++++++++++++++++++++++++----------
> 1 file changed, 43 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
> index 7f38fb55f223..d87962eda1ed 100644
> --- a/drivers/cpufreq/acpi-cpufreq.c
> +++ b/drivers/cpufreq/acpi-cpufreq.c
> @@ -66,6 +66,8 @@ enum {
>
> struct acpi_cpufreq_data {
> struct cpufreq_frequency_table *freq_table;
> + unsigned int cached_lookup_freq;
> + struct cpufreq_frequency_table *cached_lookup_entry;
This could have been an integer value 'Index', which could have been
used together with the freq-table to get the freq we wanted.
And, then we can move these two fields into the cpufreq_policy
structure and make them part of the first patch itself.
> unsigned int resume;
> unsigned int cpu_feature;
> unsigned int acpi_perf_cpu;
> @@ -458,26 +460,53 @@ static int acpi_cpufreq_target(struct cpufreq_policy
> *policy,
> return result;
> }
>
> -unsigned int acpi_cpufreq_fast_switch(struct cpufreq_policy *policy,
> - unsigned int target_freq)
> +/*
> + * Find the closest frequency above target_freq.
> + *
> + * The table is sorted in the reverse order with respect to the
> + * frequency and all of the entries are valid (see the initialization).
> + */
> +static inline struct cpufreq_frequency_table
> +*lookup_freq(struct cpufreq_frequency_table *table, unsigned int target_freq)
> {
> - struct acpi_cpufreq_data *data = policy->driver_data;
> - struct acpi_processor_performance *perf;
> - struct cpufreq_frequency_table *entry;
> - unsigned int next_perf_state, next_freq, freq;
> + struct cpufreq_frequency_table *entry = table;
> + unsigned int freq;
>
> - /*
> - * Find the closest frequency above target_freq.
> - *
> - * The table is sorted in the reverse order with respect to the
> - * frequency and all of the entries are valid (see the initialization).
> - */
> - entry = data->freq_table;
> do {
> entry++;
> freq = entry->frequency;
> } while (freq >= target_freq && freq != CPUFREQ_TABLE_END);
> entry--;
> +
> + return entry;
> +}
> +
> +unsigned int acpi_cpufreq_resolve_freq(struct cpufreq_policy *policy,
> + unsigned int target_freq)
> +{
> + struct acpi_cpufreq_data *data = policy->driver_data;
> + struct cpufreq_frequency_table *entry;
> +
> + data->cached_lookup_freq = target_freq;
> + entry = lookup_freq(data->freq_table, target_freq);
> + data->cached_lookup_entry = entry;
> +
> + return entry->frequency;
> +}
> +
And then we could remove this callback from acpi-cpufreq.
> +unsigned int acpi_cpufreq_fast_switch(struct cpufreq_policy *policy,
> + unsigned int target_freq)
> +{
> + struct acpi_cpufreq_data *data = policy->driver_data;
> + struct acpi_processor_performance *perf;
> + struct cpufreq_frequency_table *entry;
> + unsigned int next_perf_state, next_freq;
> +
> + if (data->cached_lookup_entry &&
> + data->cached_lookup_freq == target_freq)
> + entry = data->cached_lookup_entry;
> + else
> + entry = lookup_freq(data->freq_table, target_freq);
And a static inline callback in cpufreq.h to get this entry.
> next_freq = entry->frequency;
> next_perf_state = entry->driver_data;
>
> @@ -918,6 +947,7 @@ static struct cpufreq_driver acpi_cpufreq_driver = {
> .verify = cpufreq_generic_frequency_table_verify,
> .target_index = acpi_cpufreq_target,
> .fast_switch = acpi_cpufreq_fast_switch,
> + .resolve_freq = acpi_cpufreq_resolve_freq,
> .bios_limit = acpi_processor_get_bios_limit,
> .init = acpi_cpufreq_cpu_init,
> .exit = acpi_cpufreq_cpu_exit,
Sounds reasonable ?
--
viresh
