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SubjectRe: [PATCH] cpufreq: Return 0 from ->fast_switch() on errors
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On Wednesday, August 9, 2017 6:51:46 AM CEST Viresh Kumar wrote:
> CPUFREQ_ENTRY_INVALID is a special symbol which is used to specify that
> an entry in the cpufreq table is invalid. But using it outside of the
> scope of the cpufreq table looks a bit incorrect.
>
> We can represent an invalid frequency by writing it as 0 instead if we
> need. Note that it is already done that way for the return value of the
> ->get() callback.
>
> Lets do the same for ->fast_switch() and not use CPUFREQ_ENTRY_INVALID
> outside of the scope of cpufreq table.
>
> Also update the comment over cpufreq_driver_fast_switch() to clearly
> mention what this returns.
>
> None of the drivers return CPUFREQ_ENTRY_INVALID as of now from
> ->fast_switch() callback and so we don't need to update any of those.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> drivers/cpufreq/cpufreq.c | 7 ++++---
> kernel/sched/cpufreq_schedutil.c | 2 +-
> 2 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index b2cc98551fc3..9588e15da26b 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1832,9 +1832,10 @@ EXPORT_SYMBOL(cpufreq_unregister_notifier);
> * twice in parallel for the same policy and that it will never be called in
> * parallel with either ->target() or ->target_index() for the same policy.
> *
> - * If CPUFREQ_ENTRY_INVALID is returned by the driver's ->fast_switch()
> - * callback to indicate an error condition, the hardware configuration must be
> - * preserved.
> + * Returns the actual frequency set for the CPU.
> + *
> + * If 0 is returned by the driver's ->fast_switch() callback to indicate an
> + * error condition, the hardware configuration must be preserved.
> */
> unsigned int cpufreq_driver_fast_switch(struct cpufreq_policy *policy,
> unsigned int target_freq)
> diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
> index 5465bf221e8f..2e74c49776be 100644
> --- a/kernel/sched/cpufreq_schedutil.c
> +++ b/kernel/sched/cpufreq_schedutil.c
> @@ -123,7 +123,7 @@ static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time,
>
> if (policy->fast_switch_enabled) {
> next_freq = cpufreq_driver_fast_switch(policy, next_freq);
> - if (next_freq == CPUFREQ_ENTRY_INVALID)
> + if (!next_freq)
> return;
>
> policy->cur = next_freq;
>

Applied, thanks!


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