[PATCH v5 1/9] cpuidle: Add commonly used functionality for consolidation

[Jean Pihet]

Robert,

On Mon, Feb 27, 2012 at 5:47 AM, Robert Lee <rob.lee at linaro.org> wrote:
> Add functionality that is commonly duplicated by various platforms.
>
> Signed-off-by: Robert Lee <rob.lee at linaro.org>
> ---
>  drivers/cpuidle/cpuidle.c |   37 ++++++++++++++++++------------
>  include/linux/cpuidle.h   |   55 +++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 77 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
...

> diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
> index 712abcc..6563683 100644
> --- a/include/linux/cpuidle.h
> +++ b/include/linux/cpuidle.h
> @@ -15,6 +15,7 @@
>  #include <linux/list.h>
>  #include <linux/kobject.h>
>  #include <linux/completion.h>
> +#include <linux/hrtimer.h>
>
>  #define CPUIDLE_STATE_MAX      8
>  #define CPUIDLE_NAME_LEN       16
> @@ -56,6 +57,16 @@ struct cpuidle_state {
>
>  #define CPUIDLE_DRIVER_FLAGS_MASK (0xFFFF0000)
>
> +/* Common ARM WFI state */
> +#define CPUIDLE_ARM_WFI_STATE {\
> +       .enter                  = cpuidle_simple_enter,\
> +       .exit_latency           = 1,\
> +       .target_residency       = 1,\
> +       .flags                  = CPUIDLE_FLAG_TIME_VALID,\
> +       .name                   = "WFI",\
> +       .desc                   = "ARM core clock gating (WFI)",\
> +}
This macro should belong to an ARM only header.

> +
>  /**
>  * cpuidle_get_statedata - retrieves private driver state data
>  * @st_usage: the state usage statistics
> @@ -122,6 +133,14 @@ struct cpuidle_driver {
>        struct module           *owner;
>
>        unsigned int            power_specified:1;
> +       /*
> +        * use the core cpuidle time keeping. This has been implemented for the
> +        * entire driver instead of per state as currently the device enter
> +        * fuction allows the entered state to change which requires handling
> +        * that requires a (subjectively) unnecessary decrease to efficiency
> +        * in this commonly called code.
> +        */
> +       unsigned int            en_core_tk_irqen:1;
Does the description reads as 'the time accounting is only performed
if en_core_tk_irqen is set'?
Also it suggests that changing (i.e. demoting) the state is kind of a
problem, which is unclear. IIUC the state change is handled correctly
in cpuidle_idle_call, is that correct?

>        struct cpuidle_state    states[CPUIDLE_STATE_MAX];
>        int                     state_count;
>        int                     safe_state_index;
> @@ -140,6 +159,39 @@ extern void cpuidle_pause_and_lock(void);
>  extern void cpuidle_resume_and_unlock(void);
>  extern int cpuidle_enable_device(struct cpuidle_device *dev);
>  extern void cpuidle_disable_device(struct cpuidle_device *dev);
> +extern int cpuidle_simple_enter(struct cpuidle_device *dev,
> +               struct cpuidle_driver *drv, int index);
> +
> +/**
> + * cpuidle_enter_wrap - performing timekeeping and irq around enter function
> + * @dev: pointer to a valid cpuidle_device object
> + * @drv: pointer to a valid cpuidle_driver object
> + * @index: index of the target cpuidle state.
> + */
> +static inline int cpuidle_wrap_enter(struct cpuidle_device *dev,
> +                               struct cpuidle_driver *drv, int index,
> +                               int (*enter)(struct cpuidle_device *dev,
> +                                       struct cpuidle_driver *drv, int index))
The function name does not match the description (cpuidle_enter_wrap
vs cpuidle_wrap_enter).

> +{
> +       ktime_t time_start, time_end;
> +       s64 diff;
> +
> +       time_start = ktime_get();
> +
> +       index = enter(dev, drv, index);
> +
> +       time_end = ktime_get();
> +
> +       local_irq_enable();
> +
> +       diff = ktime_to_us(ktime_sub(time_end, time_start));
> +       if (diff > INT_MAX)
> +               diff = INT_MAX;
> +
> +       dev->last_residency = (int) diff;
> +
> +       return index;
> +}
>
>  #else
>  static inline void disable_cpuidle(void) { }
...

Regards,
Jean