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SubjectRe: [PATCH V2 3/5] cpuidle: idle: menu: Don't reflect when a state selection failed
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On Wednesday, October 29, 2014 09:54:43 AM Kevin Hilman wrote:
> Daniel Lezcano <daniel.lezcano@linaro.org> writes:
>
> > On 10/28/2014 08:01 AM, Preeti Murthy wrote:
> >> On Thu, Oct 23, 2014 at 2:31 PM, Daniel Lezcano
> >> <daniel.lezcano@linaro.org> wrote:
> >>> In the current code, the check to reflect or not the outcoming state is done
> >>> against the idle state which has been chosen and its value.
> >>>
> >>> Instead of doing a check in each of the reflect functions, just don't call reflect
> >>> if something went wrong in the idle path.
> >>>
> >>> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> >>> Acked-by: Nicolas Pitre <nico@linaro.org>
> >>> ---
> >>> drivers/cpuidle/governors/ladder.c | 3 +--
> >>> drivers/cpuidle/governors/menu.c | 4 +---
> >>> kernel/sched/idle.c | 3 ++-
> >>> 3 files changed, 4 insertions(+), 6 deletions(-)
> >>>
> >>> diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c
> >>> index fb396d6..c0b36a8 100644
> >>> --- a/drivers/cpuidle/governors/ladder.c
> >>> +++ b/drivers/cpuidle/governors/ladder.c
> >>> @@ -165,8 +165,7 @@ static int ladder_enable_device(struct cpuidle_driver *drv,
> >>> static void ladder_reflect(struct cpuidle_device *dev, int index)
> >>> {
> >>> struct ladder_device *ldev = &__get_cpu_var(ladder_devices);
> >>> - if (index > 0)
> >>> - ldev->last_state_idx = index;
> >>> + ldev->last_state_idx = index;
> >>> }
> >>>
> >>> static struct cpuidle_governor ladder_governor = {
> >>> diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
> >>> index a17515f..3907301 100644
> >>> --- a/drivers/cpuidle/governors/menu.c
> >>> +++ b/drivers/cpuidle/governors/menu.c
> >>> @@ -365,9 +365,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
> >>> static void menu_reflect(struct cpuidle_device *dev, int index)
> >>> {
> >>> struct menu_device *data = &__get_cpu_var(menu_devices);
> >>> - data->last_state_idx = index;
> >>> - if (index >= 0)
> >>> - data->needs_update = 1;
> >>> + data->needs_update = 1;
> >>
> >> Why is the last_state_idx not getting updated ?
> >
> > Oups, right. This is missing.
> >
> > Thanks for pointing this out.
> >
> > By the way, I don't think a back end driver is changing the selected
> > state currently and I am not sure this is desirable since we want to
> > trust the state we are going (as a best effort).
>
> FYI, the OMAP3 backend driver can does not always obey the selected
> state, and will return a different state than the one requested.

The ACPI driver can do that as well.

--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.


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