On 23-10-20, 17:35, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
>
> Generally, a cpufreq driver may need to update some internal upper
> and lower frequency boundaries on policy max and min changes,
> respectively, but currently this does not work if the target
> frequency does not change along with the policy limit.
>
> Namely, if the target frequency does not change along with the
> policy min or max, the "target_freq == policy->cur" check in
> __cpufreq_driver_target() prevents driver callbacks from being
> invoked and they do not even have a chance to update the
> corresponding internal boundary.
>
> This particularly affects the "powersave" and "performance"
> governors that always set the target frequency to one of the
> policy limits and it never changes when the other limit is updated.
>
> To allow cpufreq the drivers needing to update internal frequency
> boundaries on policy limits changes to avoid this issue, introduce
> a new driver flag, CPUFREQ_NEED_UPDATE_LIMITS, that (when set) will
> neutralize the check mentioned above.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
> ---
>
> New patch in v2.
>
> ---
> drivers/cpufreq/cpufreq.c | 3 ++-
> include/linux/cpufreq.h | 10 +++++++++-
> 2 files changed, 11 insertions(+), 2 deletions(-)
>
> Index: linux-pm/include/linux/cpufreq.h
> ===================================================================
> --- linux-pm.orig/include/linux/cpufreq.h
> +++ linux-pm/include/linux/cpufreq.h
> @@ -297,7 +297,7 @@ __ATTR(_name, 0644, show_##_name, store_
>
> struct cpufreq_driver {
> char name[CPUFREQ_NAME_LEN];
> - u8 flags;
> + u16 flags;
> void *driver_data;
>
> /* needed by all drivers */
> @@ -417,6 +417,14 @@ struct cpufreq_driver {
> */
> #define CPUFREQ_IS_COOLING_DEV BIT(7)
>
> +/*
> + * Set by drivers that need to update internale upper and lower boundaries
> along
> + * with the target frequency and so the core and governors should also invoke
> + * the diver if the target frequency does not change, but the policy min or
> max
> + * may have changed.
> + */
> +#define CPUFREQ_NEED_UPDATE_LIMITS BIT(8)
> +
> int cpufreq_register_driver(struct cpufreq_driver *driver_data);
> int cpufreq_unregister_driver(struct cpufreq_driver *driver_data);
>
> Index: linux-pm/drivers/cpufreq/cpufreq.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/cpufreq.c
> +++ linux-pm/drivers/cpufreq/cpufreq.c
> @@ -2191,7 +2191,8 @@ int __cpufreq_driver_target(struct cpufr
> * exactly same freq is called again and so we can save on few function
> * calls.
> */
> - if (target_freq == policy->cur)
> + if (target_freq == policy->cur &&
> + !(cpufreq_driver->flags & CPUFREQ_NEED_UPDATE_LIMITS))
I was wondering if the same change should be made in the target_index part as we
do this kind of check again ? But then I thought that since we know there are no
users of that right now, why bother :)
Acked-by: Viresh Kumar <viresh.ku...@linaro.org>
--
viresh
