The patch prepares devfreq device for handling suspend/resume
functionality. The new fields will store needed information during this
process. Devfreq framework handles opp-suspend DT entry and there is no
need of modyfications in the drivers code. It uses atomic variables to
make sure no race condition affects the process.
Suggested-by: Tobias Jakobi <tjak...@math.uni-bielefeld.de>
Suggested-by: Chanwoo Choi <cw00.c...@samsung.com>
Signed-off-by: Lukasz Luba <l.l...@partner.samsung.com>
---
drivers/devfreq/devfreq.c | 47 +++++++++++++++++++++++++++++++++++++++++------
include/linux/devfreq.h | 7 +++++++
2 files changed, 48 insertions(+), 6 deletions(-)
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index a9fd61b..46517b6 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -316,6 +316,10 @@ static int devfreq_set_target(struct devfreq *devfreq,
unsigned long new_freq,
"Couldn't update frequency transition information.\n");
devfreq->previous_freq = new_freq;
+
+ if (devfreq->suspend_freq)
+ devfreq->resume_freq = cur_freq;
+
return err;
}
@@ -667,6 +671,9 @@ struct devfreq *devfreq_add_device(struct device *dev,
}
devfreq->max_freq = devfreq->scaling_max_freq;
+ devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
+ atomic_set(&devfreq->suspend_count, 0);
+
dev_set_name(&devfreq->dev, "devfreq%d",
atomic_inc_return(&devfreq_no));
err = device_register(&devfreq->dev);
@@ -867,14 +874,28 @@ EXPORT_SYMBOL(devm_devfreq_remove_device);
*/
int devfreq_suspend_device(struct devfreq *devfreq)
{
+ int ret;
+
if (!devfreq)
return -EINVAL;
- if (!devfreq->governor)
+ if (atomic_inc_return(&devfreq->suspend_count) > 1)
return 0;
- return devfreq->governor->event_handler(devfreq,
- DEVFREQ_GOV_SUSPEND, NULL);
+ if (devfreq->governor) {
+ ret = devfreq->governor->event_handler(devfreq,
+ DEVFREQ_GOV_SUSPEND, NULL);
+ if (ret)
+ return ret;
+ }
+
+ if (devfreq->suspend_freq) {
+ ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
}
EXPORT_SYMBOL(devfreq_suspend_device);
@@ -888,14 +909,28 @@ EXPORT_SYMBOL(devfreq_suspend_device);
*/
int devfreq_resume_device(struct devfreq *devfreq)
{
+ int ret;
+
if (!devfreq)
return -EINVAL;
- if (!devfreq->governor)
+ if (atomic_dec_return(&devfreq->suspend_count) >= 1)
return 0;
- return devfreq->governor->event_handler(devfreq,
- DEVFREQ_GOV_RESUME, NULL);
+ if (devfreq->resume_freq) {
+ ret = devfreq_set_target(devfreq, devfreq->resume_freq, 0);
+ if (ret)
+ return ret;
+ }
+
+ if (devfreq->governor) {
+ ret = devfreq->governor->event_handler(devfreq,
+ DEVFREQ_GOV_RESUME, NULL);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
}
EXPORT_SYMBOL(devfreq_resume_device);
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index e4963b0..d985199 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -131,6 +131,9 @@ struct devfreq_dev_profile {
* @scaling_min_freq: Limit minimum frequency requested by OPP interface
* @scaling_max_freq: Limit maximum frequency requested by OPP interface
* @stop_polling: devfreq polling status of a device.
+ * @suspend_freq: frequency of a device set during suspend phase.
+ * @resume_freq: frequency of a device set in resume phase.
+ * @suspend_count: suspend requests counter for a device.
* @total_trans: Number of devfreq transitions
* @trans_table: Statistics of devfreq transitions
* @time_in_state: Statistics of devfreq states
@@ -167,6 +170,10 @@ struct devfreq {
unsigned long scaling_max_freq;
bool stop_polling;
+ unsigned long suspend_freq;
+ unsigned long resume_freq;
+ atomic_t suspend_count;
+
/* information for device frequency transition */
unsigned int total_trans;
unsigned int *trans_table;
--
2.7.4
