Hi Chanwoo,

On 12/6/18 2:17 AM, Chanwoo Choi wrote:

Hi Lukasz,

On 2018년 12월 05일 20:05, Lukasz Luba wrote:

quoted

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 <redacted>
Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Lukasz Luba <redacted>
---
  drivers/devfreq/devfreq.c | 47 +++++++++++++++++++++++++++++++++++++++++------
  include/linux/devfreq.h   |  7 +++++++
  2 files changed, 48 insertions(+), 6 deletions(-)

Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>

Thank you for the review and comments for the whole patch series.

Regards,
Lukasz

quoted

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;