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cpuidle: ladder: Add per CPU PM QoS resume latency support 

Individual CPUs may have special requirements to not enter
deep idle states. For example, a CPU running real time
applications would not want to enter deep idle states to
avoid latency impacts. At the same time other CPUs that
do not have such a requirement could allow deep idle
states to save power.

This was already implemented in the menu governor.
Implementing similar changes in the ladder governor which
gets selected when CONFIG_NO_HZ and CONFIG_NO_HZ_IDLE are not
set. Refer following commits for the menu governor changes.

Signed-off-by: Ramesh Thomas <ramesh.thomas@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
hifive-unleashed-5.1
Ramesh Thomas 2017-10-26 19:01:34 -07:00 committed by Rafael J. Wysocki
parent 4e37fd4d5d
commit c523c68da2
1 changed files with 7 additions and 0 deletions
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7
drivers/cpuidle/governors/ladder.c
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@ -17,6 +17,7 @@
#include <linux/pm_qos.h>
#include <linux/jiffies.h>
#include <linux/tick.h>
#include <linux/cpu.h>
#include <asm/io.h>
#include <linux/uaccess.h>
@ -67,10 +68,16 @@ static int ladder_select_state(struct cpuidle_driver *drv,
struct cpuidle_device *dev)
{
struct ladder_device *ldev = this_cpu_ptr(&ladder_devices);
struct device *device = get_cpu_device(dev->cpu);
struct ladder_device_state *last_state;
int last_residency, last_idx = ldev->last_state_idx;
int first_idx = drv->states[0].flags & CPUIDLE_FLAG_POLLING ? 1 : 0;
int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
int resume_latency = dev_pm_qos_raw_read_value(device);
if (resume_latency < latency_req &&
resume_latency != PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
latency_req = resume_latency;
/* Special case when user has set very strict latency requirement */
if (unlikely(latency_req == 0)) {