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SubjectRe: [PATCH 1/2] cpufreq: Add stop callback to cpufreq_driver interface
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On 18 March 2014 22:52,  <dirk.brandewie@gmail.com> wrote:
> From: Dirk Brandewie <dirk.j.brandewie@intel.com>
>
> This callback allows the driver to do clean up before the CPU is
> completely down and its state cannot be modified. This is used
> by the intel_pstate driver to reduce the requested P state prior to
> the core going away. This is required because the requested P state
> of the offline core is used to select the package P state. This
> effectively sets the floor package P state to the requested P state on
> the offline core.
>
> Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
> ---
> Documentation/cpu-freq/cpu-drivers.txt | 8 +++++++-
> drivers/cpufreq/cpufreq.c | 3 ++-
> include/linux/cpufreq.h | 1 +
> 3 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt
> index 8b1a445..79def80 100644
> --- a/Documentation/cpu-freq/cpu-drivers.txt
> +++ b/Documentation/cpu-freq/cpu-drivers.txt
> @@ -61,7 +61,13 @@ target_index - See below on the differences.
>
> And optionally
>
> -cpufreq_driver.exit - A pointer to a per-CPU cleanup function.
> +cpufreq_driver.exit - A pointer to a per-CPU cleanup
> + function called during CPU_POST_DEAD
> + phase of cpu hotplug process.
> +
> +cpufreq_driver.stop - A pointer to a per-CPU stop function
> + called during CPU_DOWN_PREPARE phase of
> + cpu hotplug process.
>
> cpufreq_driver.resume - A pointer to a per-CPU resume function
> which is called with interrupts disabled
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index cf485d9..6e6beae 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1336,7 +1336,8 @@ static int __cpufreq_remove_dev_prepare(struct device *dev,
> __func__, new_cpu, cpu);
> }
> }
> - }
> + } else if (cpufreq_driver->stop)
> + cpufreq_driver->stop(policy);
>
> return 0;
> }
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 4d89e0e..ff8db19 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -224,6 +224,7 @@ struct cpufreq_driver {
> int (*bios_limit) (int cpu, unsigned int *limit);
>
> int (*exit) (struct cpufreq_policy *policy);
> + int (*stop) (struct cpufreq_policy *policy);
> int (*suspend) (struct cpufreq_policy *policy);
> int (*resume) (struct cpufreq_policy *policy);
> struct freq_attr **attr;

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>


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