Re: [linux-pm] [RFC 1/4] cpuidle: define the enter function in the driver structure
From: Deepthi Dharwar <hidden>
Date: 2012-06-08 17:33:20
Also in:
linux-acpi, lkml
Hi Daniel, On 06/08/2012 09:32 PM, Daniel Lezcano wrote:
We have the state index passed as parameter to the 'enter' function. Most of the drivers assign their 'enter' functions several times in the cpuidle_state structure, as we have the index, we can delegate to the driver to handle their own callback array. That will have the benefit of removing multiple lines of code in the different drivers. In order to smoothly modify the driver, the 'enter' function are in the driver structure and in the cpuidle state structure. That will let the time to modify the different drivers one by one. So the 'cpuidle_enter' function checks if the 'enter' callback is assigned in the driver structure and use it, otherwise it invokes the 'enter' assigned to the cpuidle_state.
Currently, the backend driver initializes all the cpuidle states supported on the platform, and each state can have its own enter routine which can be unique This is a clean approach. By moving the enter routine into the driver, we are enforcing in having only one enter state. There is unnecessary overhead involved in calling a wrapper routine just to index into the right idle state routine for many platforms at runtime.
quoted hunk ↗ jump to hunk
Signed-off-by: Daniel Lezcano <redacted> --- drivers/cpuidle/cpuidle.c | 4 +++- include/linux/cpuidle.h | 1 + 2 files changed, 4 insertions(+), 1 deletions(-)diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index d90519c..155dee7 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c@@ -46,7 +46,9 @@ static inline int cpuidle_enter(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { struct cpuidle_state *target_state = &drv->states[index]; - return target_state->enter(dev, drv, index); + + return drv->enter(dev, drv, index) ? drv->enter(dev, drv, index) : + target_state->enter(dev, drv, index); } static inline int cpuidle_enter_tk(struct cpuidle_device *dev,diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h index 6c26a3d..d82e169 100644 --- a/include/linux/cpuidle.h +++ b/include/linux/cpuidle.h@@ -130,6 +130,7 @@ struct cpuidle_driver { struct cpuidle_state states[CPUIDLE_STATE_MAX]; int state_count; int safe_state_index; + int (*enter)(struct cpuidle_device *, struct cpuidle_driver *, int); }; #ifdef CONFIG_CPU_IDLE
Cheers, Deepthi