[PATCH v2 0/5] devfreq: handle suspend/resume

[PATCH v2 0/5] devfreq: handle suspend/resume

[Lukasz Luba]

Hi all,

This v2 patch set aims to address the issue with devfreq devices' frequency
during suspend/resume. It extends suspend/resume by calls to Devfreq
framework. In the devfreq framework there is a small refactoring to avoid
code duplication in changging frequency (patch 1) and there are extensions
for suspending devices. The suspending device has now chance to set proper
state when the system is going for suspend. This phase is the right place
to set needed frequences for the next resume process.

It has been tested on Odroid u3 with Exynos 4412.

The patch set draws on Tobias Jakobi's work posted ~2 years ago, who tried
to solve issue with devfreq device's frequency during suspend/resume.
During the discussion on LKML some corner cases and comments appeared
related to the design. This patch set address them keeping in mind
suggestions from Chanwoo Choi.
Tobias's paches:
https://www.spinics.net/lists/linux-samsung-soc/msg56602.html 

Changes:
v2:
- refactored patchset and merget patch 1 and 3 as suggested by Chanwoo Choi,
- changed devfreq_{susped|resume}_device functions,
- added doxygen information for new entres in 'struct devfreq',
- devfreq_set_target skipped one argument, now resume_freq is set inside,
- minor changes addresing comments from maintainers regarding the style,

Regards,
Lukasz Luba

Lukasz Luba (5):
  devfreq: refactor set_target frequency function
  devfreq: add support for suspend/resume of a devfreq device
  devfreq: add devfreq_suspend/resume() functions
  drivers: power: suspend: call devfreq suspend/resume
  arm: dts: exynos4: opp-suspend in DMC and leftbus

 arch/arm/boot/dts/exynos4210.dtsi |   2 +
 arch/arm/boot/dts/exynos4412.dtsi |   2 +
 drivers/base/power/main.c         |   3 +
 drivers/devfreq/devfreq.c         | 155 +++++++++++++++++++++++++++++---------
 include/linux/devfreq.h           |  13 ++++
 5 files changed, 141 insertions(+), 34 deletions(-)

-- 
2.7.4

[PATCH v2 1/5] devfreq: refactor set_target frequency function

[Lukasz Luba]

The refactoring is needed for the new client in devfreq: suspend.
To avoid code duplication, move it to the new local function
devfreq_set_target.

The patch is based on earlier work by Tobias Jakobi.

Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
---
 drivers/devfreq/devfreq.c | 62 +++++++++++++++++++++++++++--------------------
 1 file changed, 36 insertions(+), 26 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 1414130..a9fd61b 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -285,6 +285,40 @@ static int devfreq_notify_transition(struct devfreq *devfreq,
 	return 0;
 }
 
+static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
+			      u32 flags)
+{
+	struct devfreq_freqs freqs;
+	unsigned long cur_freq;
+	int err = 0;
+
+	if (devfreq->profile->get_cur_freq)
+		devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
+	else
+		cur_freq = devfreq->previous_freq;
+
+	freqs.old = cur_freq;
+	freqs.new = new_freq;
+	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
+
+	err = devfreq->profile->target(devfreq->dev.parent, &new_freq, flags);
+	if (err) {
+		freqs.new = cur_freq;
+		devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
+		return err;
+	}
+
+	freqs.new = new_freq;
+	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
+
+	if (devfreq_update_status(devfreq, new_freq))
+		dev_err(&devfreq->dev,
+			"Couldn't update frequency transition information.\n");
+
+	devfreq->previous_freq = new_freq;
+	return err;
+}
+
 /* Load monitoring helper functions for governors use */
 
 /**
@@ -296,8 +330,7 @@ static int devfreq_notify_transition(struct devfreq *devfreq,
  */
 int update_devfreq(struct devfreq *devfreq)
 {
-	struct devfreq_freqs freqs;
-	unsigned long freq, cur_freq, min_freq, max_freq;
+	unsigned long freq, min_freq, max_freq;
 	int err = 0;
 	u32 flags = 0;
 
@@ -333,31 +366,8 @@ int update_devfreq(struct devfreq *devfreq)
 		flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
 	}
 
-	if (devfreq->profile->get_cur_freq)
-		devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
-	else
-		cur_freq = devfreq->previous_freq;
-
-	freqs.old = cur_freq;
-	freqs.new = freq;
-	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
+	return devfreq_set_target(devfreq, freq, flags);
 
-	err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
-	if (err) {
-		freqs.new = cur_freq;
-		devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
-		return err;
-	}
-
-	freqs.new = freq;
-	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
-
-	if (devfreq_update_status(devfreq, freq))
-		dev_err(&devfreq->dev,
-			"Couldn't update frequency transition information.\n");
-
-	devfreq->previous_freq = freq;
-	return err;
 }
 EXPORT_SYMBOL(update_devfreq);
 
-- 
2.7.4

[PATCH v2 2/5] devfreq: add support for suspend/resume of a devfreq device

[Lukasz Luba]

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.

The patch is based on earlier work by Tobias Jakobi.

Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
---
 drivers/devfreq/devfreq.c | 51 +++++++++++++++++++++++++++++++++++++++--------
 include/linux/devfreq.h   |  7 +++++++
 2 files changed, 50 insertions(+), 8 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index a9fd61b..36bed24 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)
-		return 0;
+	if (devfreq->governor) {
+		ret = devfreq->governor->event_handler(devfreq,
+					DEVFREQ_GOV_SUSPEND, NULL);
+		if (ret)
+			return ret;
+	}
+
+	if (devfreq->suspend_freq) {
+		if (atomic_inc_return(&devfreq->suspend_count) > 1)
+			return 0;
+
+		ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0);
+		if (ret)
+			return ret;
+	}
 
-	return devfreq->governor->event_handler(devfreq,
-				DEVFREQ_GOV_SUSPEND, NULL);
+	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)
-		return 0;
+	if (devfreq->resume_freq) {
+		if (atomic_dec_return(&devfreq->suspend_count) >= 1)
+			return 0;
 
-	return devfreq->governor->event_handler(devfreq,
-				DEVFREQ_GOV_RESUME, NULL);
+		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

[PATCH v2 3/5] devfreq: add devfreq_suspend/resume() functions

[Lukasz Luba]

This patch adds implementation for global suspend/resume for
devfreq framework. System suspend will next use these functions.

The patch is based on earlier work by Tobias Jakobi.

Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
---
 drivers/devfreq/devfreq.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/devfreq.h   |  6 ++++++
 2 files changed, 48 insertions(+)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 36bed24..7d60423 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -935,6 +935,48 @@ int devfreq_resume_device(struct devfreq *devfreq)
 EXPORT_SYMBOL(devfreq_resume_device);
 
 /**
+ * devfreq_suspend() - Suspend devfreq governors and devices
+ *
+ * Called during system wide Suspend/Hibernate cycles for suspending governors
+ * and devices preserving the state for resume. On some platforms the devfreq
+ * device must have precise state (frequency) after resume in order to provide
+ * fully operating setup.
+ */
+void devfreq_suspend(void)
+{
+	struct devfreq *devfreq;
+	int ret;
+
+	mutex_lock(&devfreq_list_lock);
+	list_for_each_entry(devfreq, &devfreq_list, node) {
+		ret = devfreq_suspend_device(devfreq);
+		if (ret)
+			dev_warn(&devfreq->dev, "device suspend failed\n");
+	}
+	mutex_unlock(&devfreq_list_lock);
+}
+
+/**
+ * devfreq_resume() - Resume devfreq governors and devices
+ *
+ * Called during system wide Suspend/Hibernate cycle for resuming governors and
+ * devices that are suspended with devfreq_suspend().
+ */
+void devfreq_resume(void)
+{
+	struct devfreq *devfreq;
+	int ret;
+
+	mutex_lock(&devfreq_list_lock);
+	list_for_each_entry(devfreq, &devfreq_list, node) {
+		ret = devfreq_resume_device(devfreq);
+		if (ret)
+			dev_warn(&devfreq->dev, "device resume failed\n");
+	}
+	mutex_unlock(&devfreq_list_lock);
+}
+
+/**
  * devfreq_add_governor() - Add devfreq governor
  * @governor:	the devfreq governor to be added
  */
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index d985199..fbffa74 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -205,6 +205,9 @@ extern void devm_devfreq_remove_device(struct device *dev,
 extern int devfreq_suspend_device(struct devfreq *devfreq);
 extern int devfreq_resume_device(struct devfreq *devfreq);
 
+extern void devfreq_suspend(void);
+extern void devfreq_resume(void);
+
 /**
  * update_devfreq() - Reevaluate the device and configure frequency
  * @devfreq:	the devfreq device
@@ -331,6 +334,9 @@ static inline int devfreq_resume_device(struct devfreq *devfreq)
 	return 0;
 }
 
+static inline void devfreq_suspend(void) {}
+static inline void devfreq_resume(void) {}
+
 static inline struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
 					   unsigned long *freq, u32 flags)
 {
-- 
2.7.4

[PATCH v2 4/5] drivers: power: suspend: call devfreq suspend/resume

[Lukasz Luba]

Devfreq framework supports suspend of its devices.
Call the the devfreq interface and allow devfreq devices preserve/restore
their states during suspend/resume.

The patch is based on earlier work by Tobias Jakobi.

Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
---
 drivers/base/power/main.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index a690fd4..0992e67 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -32,6 +32,7 @@
 #include <trace/events/power.h>
 #include <linux/cpufreq.h>
 #include <linux/cpuidle.h>
+#include <linux/devfreq.h>
 #include <linux/timer.h>
 
 #include "../base.h"
@@ -1078,6 +1079,7 @@ void dpm_resume(pm_message_t state)
 	dpm_show_time(starttime, state, 0, NULL);
 
 	cpufreq_resume();
+	devfreq_resume();
 	trace_suspend_resume(TPS("dpm_resume"), state.event, false);
 }
 
@@ -1852,6 +1854,7 @@ int dpm_suspend(pm_message_t state)
 	trace_suspend_resume(TPS("dpm_suspend"), state.event, true);
 	might_sleep();
 
+	devfreq_suspend();
 	cpufreq_suspend();
 
 	mutex_lock(&dpm_list_mtx);
-- 
2.7.4

[PATCH v2 5/5] arm: dts: exynos4: opp-suspend in DMC and leftbus

[Lukasz Luba]

Mark the state for devfreq device while entring suspend/resume process.

The patch is based on earlier work by Tobias Jakobi.

Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
---
 arch/arm/boot/dts/exynos4210.dtsi | 2 ++
 arch/arm/boot/dts/exynos4412.dtsi | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/arch/arm/boot/dts/exynos4210.dtsi b/arch/arm/boot/dts/exynos4210.dtsi
index b6091c2..4429b72 100644
--- a/arch/arm/boot/dts/exynos4210.dtsi
+++ b/arch/arm/boot/dts/exynos4210.dtsi
@@ -298,6 +298,7 @@
 			opp-400000000 {
 				opp-hz = /bits/ 64 <400000000>;
 				opp-microvolt = <1150000>;
+				opp-suspend;
 			};
 		};
 
@@ -367,6 +368,7 @@
 			};
 			opp-200000000 {
 				opp-hz = /bits/ 64 <200000000>;
+				opp-suspend;
 			};
 		};
 	};
diff --git a/arch/arm/boot/dts/exynos4412.dtsi b/arch/arm/boot/dts/exynos4412.dtsi
index 51f72f0..908c0c4 100644
--- a/arch/arm/boot/dts/exynos4412.dtsi
+++ b/arch/arm/boot/dts/exynos4412.dtsi
@@ -432,6 +432,7 @@
 			opp-400000000 {
 				opp-hz = /bits/ 64 <400000000>;
 				opp-microvolt = <1050000>;
+				opp-suspend;
 			};
 		};
 
@@ -520,6 +521,7 @@
 			opp-200000000 {
 				opp-hz = /bits/ 64 <200000000>;
 				opp-microvolt = <1000000>;
+				opp-suspend;
 			};
 		};
 
-- 
2.7.4

Re: [PATCH v2 5/5] arm: dts: exynos4: opp-suspend in DMC and leftbus

[Krzysztof Kozlowski]

On Mon, Dec 03, 2018 at 03:31:15PM +0100, Lukasz Luba wrote:
> Mark the state for devfreq device while entring suspend/resume process.
> 
> The patch is based on earlier work by Tobias Jakobi.
> 
> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
> ---
>  arch/arm/boot/dts/exynos4210.dtsi | 2 ++
>  arch/arm/boot/dts/exynos4412.dtsi | 2 ++
>  2 files changed, 4 insertions(+)

Thanks, applied with some minor commit msg changes. In general, please
take care about title prefix (git log --oneline
arch/arm/boot/dts/exynos*) and always explain why you are doing this.
You just mentioned "what" but that is pretty obvious by looking at
commit contents. The commit msg should answer why these should be marked
as opp-suspend and why these values were chosen.

The cover letter just briefly describes "issue with devfreq devices' frequency
during suspend/resume"... but what issue?

Best regards,
Krzysztof

> 
> diff --git a/arch/arm/boot/dts/exynos4210.dtsi b/arch/arm/boot/dts/exynos4210.dtsi
> index b6091c2..4429b72 100644
> --- a/arch/arm/boot/dts/exynos4210.dtsi
> +++ b/arch/arm/boot/dts/exynos4210.dtsi
> @@ -298,6 +298,7 @@
>  			opp-400000000 {
>  				opp-hz = /bits/ 64 <400000000>;
>  				opp-microvolt = <1150000>;
> +				opp-suspend;
>  			};
>  		};
>  
> @@ -367,6 +368,7 @@
>  			};
>  			opp-200000000 {
>  				opp-hz = /bits/ 64 <200000000>;
> +				opp-suspend;
>  			};
>  		};
>  	};
> diff --git a/arch/arm/boot/dts/exynos4412.dtsi b/arch/arm/boot/dts/exynos4412.dtsi
> index 51f72f0..908c0c4 100644
> --- a/arch/arm/boot/dts/exynos4412.dtsi
> +++ b/arch/arm/boot/dts/exynos4412.dtsi
> @@ -432,6 +432,7 @@
>  			opp-400000000 {
>  				opp-hz = /bits/ 64 <400000000>;
>  				opp-microvolt = <1050000>;
> +				opp-suspend;
>  			};
>  		};
>  
> @@ -520,6 +521,7 @@
>  			opp-200000000 {
>  				opp-hz = /bits/ 64 <200000000>;
>  				opp-microvolt = <1000000>;
> +				opp-suspend;
>  			};
>  		};
>  
> -- 
> 2.7.4
> 

Re: [PATCH v2 5/5] arm: dts: exynos4: opp-suspend in DMC and leftbus

[Lukasz Luba]

Hi Krzysztof,

On 12/3/18 6:22 PM, Krzysztof Kozlowski wrote:
> On Mon, Dec 03, 2018 at 03:31:15PM +0100, Lukasz Luba wrote:
>> Mark the state for devfreq device while entring suspend/resume process.
>>
>> The patch is based on earlier work by Tobias Jakobi.
>>
>> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
>> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
>> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
>> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
>> ---
>>   arch/arm/boot/dts/exynos4210.dtsi | 2 ++
>>   arch/arm/boot/dts/exynos4412.dtsi | 2 ++
>>   2 files changed, 4 insertions(+)
> 
> Thanks, applied with some minor commit msg changes. In general, please
> take care about title prefix (git log --oneline
> arch/arm/boot/dts/exynos*) and always explain why you are doing this.
Thank you that you have applied and for the hint.

> You just mentioned "what" but that is pretty obvious by looking at
> commit contents. The commit msg should answer why these should be marked
> as opp-suspend and why these values were chosen.
> 
> The cover letter just briefly describes "issue with devfreq devices' frequency
> during suspend/resume"... but what issue?
In the cover letter there is sentence:
'The suspending device has now chance to set proper
state when the system is going for suspend. This phase is the right place
to set needed frequences for the next resume process.'
Generally speaking, there is a need of setting the right
frequency/voltage, because we need that frequency during resume,
i.e. for booting CPUs (which are poked earlier during resume than the 
buses in this design).

Regards,
Lukasz


> 
> Best regards,
> Krzysztof
> 
>>
>> diff --git a/arch/arm/boot/dts/exynos4210.dtsi b/arch/arm/boot/dts/exynos4210.dtsi
>> index b6091c2..4429b72 100644
>> --- a/arch/arm/boot/dts/exynos4210.dtsi
>> +++ b/arch/arm/boot/dts/exynos4210.dtsi
>> @@ -298,6 +298,7 @@
>>   			opp-400000000 {
>>   				opp-hz = /bits/ 64 <400000000>;
>>   				opp-microvolt = <1150000>;
>> +				opp-suspend;
>>   			};
>>   		};
>>   
>> @@ -367,6 +368,7 @@
>>   			};
>>   			opp-200000000 {
>>   				opp-hz = /bits/ 64 <200000000>;
>> +				opp-suspend;
>>   			};
>>   		};
>>   	};
>> diff --git a/arch/arm/boot/dts/exynos4412.dtsi b/arch/arm/boot/dts/exynos4412.dtsi
>> index 51f72f0..908c0c4 100644
>> --- a/arch/arm/boot/dts/exynos4412.dtsi
>> +++ b/arch/arm/boot/dts/exynos4412.dtsi
>> @@ -432,6 +432,7 @@
>>   			opp-400000000 {
>>   				opp-hz = /bits/ 64 <400000000>;
>>   				opp-microvolt = <1050000>;
>> +				opp-suspend;
>>   			};
>>   		};
>>   
>> @@ -520,6 +521,7 @@
>>   			opp-200000000 {
>>   				opp-hz = /bits/ 64 <200000000>;
>>   				opp-microvolt = <1000000>;
>> +				opp-suspend;
>>   			};
>>   		};
>>   
>> -- 
>> 2.7.4
>>
> 
> 

Re: [PATCH v2 1/5] devfreq: refactor set_target frequency function

[Chanwoo Choi]

Hi Lukasz,

On 2018년 12월 03일 23:31, Lukasz Luba wrote:
> The refactoring is needed for the new client in devfreq: suspend.
> To avoid code duplication, move it to the new local function
> devfreq_set_target.
> 
> The patch is based on earlier work by Tobias Jakobi.

As I already commented, Please remove it. You already mentioned it on cover-letter.
If you want to contain the contribution history of Tobias, you might better
to add 'Signed-off-by' or others.

> 
> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
> ---
>  drivers/devfreq/devfreq.c | 62 +++++++++++++++++++++++++++--------------------
>  1 file changed, 36 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 1414130..a9fd61b 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -285,6 +285,40 @@ static int devfreq_notify_transition(struct devfreq *devfreq,
>  	return 0;
>  }
>  
> +static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
> +			      u32 flags)
> +{
> +	struct devfreq_freqs freqs;
> +	unsigned long cur_freq;
> +	int err = 0;
> +
> +	if (devfreq->profile->get_cur_freq)
> +		devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
> +	else
> +		cur_freq = devfreq->previous_freq;
> +
> +	freqs.old = cur_freq;
> +	freqs.new = new_freq;
> +	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
> +
> +	err = devfreq->profile->target(devfreq->dev.parent, &new_freq, flags);
> +	if (err) {
> +		freqs.new = cur_freq;
> +		devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
> +		return err;
> +	}
> +
> +	freqs.new = new_freq;
> +	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
> +
> +	if (devfreq_update_status(devfreq, new_freq))
> +		dev_err(&devfreq->dev,
> +			"Couldn't update frequency transition information.\n");
> +
> +	devfreq->previous_freq = new_freq;
> +	return err;
> +}
> +
>  /* Load monitoring helper functions for governors use */
>  
>  /**
> @@ -296,8 +330,7 @@ static int devfreq_notify_transition(struct devfreq *devfreq,
>   */
>  int update_devfreq(struct devfreq *devfreq)
>  {
> -	struct devfreq_freqs freqs;
> -	unsigned long freq, cur_freq, min_freq, max_freq;
> +	unsigned long freq, min_freq, max_freq;
>  	int err = 0;
>  	u32 flags = 0;
>  
> @@ -333,31 +366,8 @@ int update_devfreq(struct devfreq *devfreq)
>  		flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
>  	}
>  
> -	if (devfreq->profile->get_cur_freq)
> -		devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
> -	else
> -		cur_freq = devfreq->previous_freq;
> -
> -	freqs.old = cur_freq;
> -	freqs.new = freq;
> -	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
> +	return devfreq_set_target(devfreq, freq, flags);
>  
> -	err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
> -	if (err) {
> -		freqs.new = cur_freq;
> -		devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
> -		return err;
> -	}
> -
> -	freqs.new = freq;
> -	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
> -
> -	if (devfreq_update_status(devfreq, freq))
> -		dev_err(&devfreq->dev,
> -			"Couldn't update frequency transition information.\n");
> -
> -	devfreq->previous_freq = freq;
> -	return err;
>  }
>  EXPORT_SYMBOL(update_devfreq);
>  
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

Re: [PATCH v2 2/5] devfreq: add support for suspend/resume of a devfreq device

[Chanwoo Choi]

Hi Lukasz,

Looks good to me. But, I add the some comments.
If you will fix it, feel free to add my tag:
Reviewed-by: Chanwoo choi <cw00.choi@samsung.com>

On 2018년 12월 03일 23:31, Lukasz Luba wrote:
> The patch prepares devfreq device for handling suspend/resume
> functionality.  The new fields will store needed information during this

nitpick. Remove unneeded space. There are two spaces between '.' and 'The new'. 

> process.  Devfreq framework handles opp-suspend DT entry and there is no

ditto.

> need of modyfications in the drivers code.  It uses atomic variables to

ditto.

> make sure no race condition affects the process.
> 
> The patch is based on earlier work by Tobias Jakobi.

Please remove it from each patch description.

> 
> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
> ---
>  drivers/devfreq/devfreq.c | 51 +++++++++++++++++++++++++++++++++++++++--------
>  include/linux/devfreq.h   |  7 +++++++
>  2 files changed, 50 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index a9fd61b..36bed24 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)
> -		return 0;
> +	if (devfreq->governor) {
> +		ret = devfreq->governor->event_handler(devfreq,
> +					DEVFREQ_GOV_SUSPEND, NULL);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (devfreq->suspend_freq) {
> +		if (atomic_inc_return(&devfreq->suspend_count) > 1)
> +			return 0;
> +
> +		ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0);
> +		if (ret)
> +			return ret;
> +	}
>  
> -	return devfreq->governor->event_handler(devfreq,
> -				DEVFREQ_GOV_SUSPEND, NULL);
> +	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)
> -		return 0;
> +	if (devfreq->resume_freq) {
> +		if (atomic_dec_return(&devfreq->suspend_count) >= 1)
> +			return 0;
>  
> -	return devfreq->governor->event_handler(devfreq,
> -				DEVFREQ_GOV_RESUME, NULL);
> +		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;
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

Re: [PATCH v2 1/5] devfreq: refactor set_target frequency function

[Chanwoo Choi]

Hi,

On 2018년 12월 04일 13:39, Chanwoo Choi wrote:
> Hi Lukasz,
> 
> On 2018년 12월 03일 23:31, Lukasz Luba wrote:
>> The refactoring is needed for the new client in devfreq: suspend.
>> To avoid code duplication, move it to the new local function
>> devfreq_set_target.
>>
>> The patch is based on earlier work by Tobias Jakobi.
> 
> As I already commented, Please remove it. You already mentioned it on cover-letter.
> If you want to contain the contribution history of Tobias, you might better
> to add 'Signed-off-by' or others.

If you will fix it, feel free to add my tag:
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>

> 
>>
>> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
>> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
>> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
>> ---
>>  drivers/devfreq/devfreq.c | 62 +++++++++++++++++++++++++++--------------------
>>  1 file changed, 36 insertions(+), 26 deletions(-)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index 1414130..a9fd61b 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -285,6 +285,40 @@ static int devfreq_notify_transition(struct devfreq *devfreq,
>>  	return 0;
>>  }
>>  
>> +static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
>> +			      u32 flags)
>> +{
>> +	struct devfreq_freqs freqs;
>> +	unsigned long cur_freq;
>> +	int err = 0;
>> +
>> +	if (devfreq->profile->get_cur_freq)
>> +		devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
>> +	else
>> +		cur_freq = devfreq->previous_freq;
>> +
>> +	freqs.old = cur_freq;
>> +	freqs.new = new_freq;
>> +	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
>> +
>> +	err = devfreq->profile->target(devfreq->dev.parent, &new_freq, flags);
>> +	if (err) {
>> +		freqs.new = cur_freq;
>> +		devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
>> +		return err;
>> +	}
>> +
>> +	freqs.new = new_freq;
>> +	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
>> +
>> +	if (devfreq_update_status(devfreq, new_freq))
>> +		dev_err(&devfreq->dev,
>> +			"Couldn't update frequency transition information.\n");
>> +
>> +	devfreq->previous_freq = new_freq;
>> +	return err;
>> +}
>> +
>>  /* Load monitoring helper functions for governors use */
>>  
>>  /**
>> @@ -296,8 +330,7 @@ static int devfreq_notify_transition(struct devfreq *devfreq,
>>   */
>>  int update_devfreq(struct devfreq *devfreq)
>>  {
>> -	struct devfreq_freqs freqs;
>> -	unsigned long freq, cur_freq, min_freq, max_freq;
>> +	unsigned long freq, min_freq, max_freq;
>>  	int err = 0;
>>  	u32 flags = 0;
>>  
>> @@ -333,31 +366,8 @@ int update_devfreq(struct devfreq *devfreq)
>>  		flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
>>  	}
>>  
>> -	if (devfreq->profile->get_cur_freq)
>> -		devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
>> -	else
>> -		cur_freq = devfreq->previous_freq;
>> -
>> -	freqs.old = cur_freq;
>> -	freqs.new = freq;
>> -	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
>> +	return devfreq_set_target(devfreq, freq, flags);
>>  
>> -	err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
>> -	if (err) {
>> -		freqs.new = cur_freq;
>> -		devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
>> -		return err;
>> -	}
>> -
>> -	freqs.new = freq;
>> -	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
>> -
>> -	if (devfreq_update_status(devfreq, freq))
>> -		dev_err(&devfreq->dev,
>> -			"Couldn't update frequency transition information.\n");
>> -
>> -	devfreq->previous_freq = freq;
>> -	return err;
>>  }
>>  EXPORT_SYMBOL(update_devfreq);
>>  
>>
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

Re: [PATCH v2 2/5] devfreq: add support for suspend/resume of a devfreq device

[Chanwoo Choi]

Hi,

On 2018년 12월 04일 14:36, Chanwoo Choi wrote:
> Hi Lukasz,
> 
> Looks good to me. But, I add the some comments.
> If you will fix it, feel free to add my tag:
> Reviewed-by: Chanwoo choi <cw00.choi@samsung.com>

Sorry. Fix typo 'choi' to 'Choi' as following.
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>

> 
> On 2018년 12월 03일 23:31, Lukasz Luba wrote:
>> The patch prepares devfreq device for handling suspend/resume
>> functionality.  The new fields will store needed information during this
> 
> nitpick. Remove unneeded space. There are two spaces between '.' and 'The new'. 
> 
>> process.  Devfreq framework handles opp-suspend DT entry and there is no
> 
> ditto.
> 
>> need of modyfications in the drivers code.  It uses atomic variables to
> 
> ditto.
> 
>> make sure no race condition affects the process.
>>
>> The patch is based on earlier work by Tobias Jakobi.
> 
> Please remove it from each patch description.
> 
>>
>> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
>> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
>> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
>> ---
>>  drivers/devfreq/devfreq.c | 51 +++++++++++++++++++++++++++++++++++++++--------
>>  include/linux/devfreq.h   |  7 +++++++
>>  2 files changed, 50 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index a9fd61b..36bed24 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)
>> -		return 0;
>> +	if (devfreq->governor) {
>> +		ret = devfreq->governor->event_handler(devfreq,
>> +					DEVFREQ_GOV_SUSPEND, NULL);
>> +		if (ret)
>> +			return ret;
>> +	}
>> +
>> +	if (devfreq->suspend_freq) {
>> +		if (atomic_inc_return(&devfreq->suspend_count) > 1)
>> +			return 0;
>> +
>> +		ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0);
>> +		if (ret)
>> +			return ret;
>> +	}
>>  
>> -	return devfreq->governor->event_handler(devfreq,
>> -				DEVFREQ_GOV_SUSPEND, NULL);
>> +	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)
>> -		return 0;
>> +	if (devfreq->resume_freq) {
>> +		if (atomic_dec_return(&devfreq->suspend_count) >= 1)
>> +			return 0;
>>  
>> -	return devfreq->governor->event_handler(devfreq,
>> -				DEVFREQ_GOV_RESUME, NULL);
>> +		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;
>>
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

Re: [PATCH v2 2/5] devfreq: add support for suspend/resume of a devfreq device

[Chanwoo Choi]

Hi Lukasz,

I add the comment about 'suspend_count'.

On 2018년 12월 04일 14:43, Chanwoo Choi wrote:
> Hi,
> 
> On 2018년 12월 04일 14:36, Chanwoo Choi wrote:
>> Hi Lukasz,
>>
>> Looks good to me. But, I add the some comments.
>> If you will fix it, feel free to add my tag:
>> Reviewed-by: Chanwoo choi <cw00.choi@samsung.com>
> 
> Sorry. Fix typo 'choi' to 'Choi' as following.
> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
> 
>>
>> On 2018년 12월 03일 23:31, Lukasz Luba wrote:
>>> The patch prepares devfreq device for handling suspend/resume
>>> functionality.  The new fields will store needed information during this
>>
>> nitpick. Remove unneeded space. There are two spaces between '.' and 'The new'. 
>>
>>> process.  Devfreq framework handles opp-suspend DT entry and there is no
>>
>> ditto.
>>
>>> need of modyfications in the drivers code.  It uses atomic variables to
>>
>> ditto.
>>
>>> make sure no race condition affects the process.
>>>
>>> The patch is based on earlier work by Tobias Jakobi.
>>
>> Please remove it from each patch description.
>>
>>>
>>> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
>>> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
>>> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
>>> ---
>>>  drivers/devfreq/devfreq.c | 51 +++++++++++++++++++++++++++++++++++++++--------
>>>  include/linux/devfreq.h   |  7 +++++++
>>>  2 files changed, 50 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>> index a9fd61b..36bed24 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)
>>> -		return 0;
>>> +	if (devfreq->governor) {
>>> +		ret = devfreq->governor->event_handler(devfreq,
>>> +					DEVFREQ_GOV_SUSPEND, NULL);
>>> +		if (ret)
>>> +			return ret;
>>> +	}
>>> +
>>> +	if (devfreq->suspend_freq) {
>>> +		if (atomic_inc_return(&devfreq->suspend_count) > 1)
>>> +			return 0;
>>> +
>>> +		ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0);
>>> +		if (ret)
>>> +			return ret;
>>> +	}

In this patch, if some users call 'devfreq_suspend_device' twice,
'devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_SUSPEND, NULL)'
is called twice but devfreq_set_target() is called only one.
I knew that it is no problem for operation.

But,
I think that you better to use 'suspend_count' as the reference count
of devfreq_suspend/resume_device(). But, if you use 'suspend_count'
in order to check whether this devfreq is suspended or not,
we can reduce the unneeded redundant call when calling it twice.

clock and regulator used the 'reference count' method in order to
remove the redundant call.


>>>  
>>> -	return devfreq->governor->event_handler(devfreq,
>>> -				DEVFREQ_GOV_SUSPEND, NULL);
>>> +	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)
>>> -		return 0;
>>> +	if (devfreq->resume_freq) {
>>> +		if (atomic_dec_return(&devfreq->suspend_count) >= 1)
>>> +			return 0;

ditto.

>>>  
>>> -	return devfreq->governor->event_handler(devfreq,
>>> -				DEVFREQ_GOV_RESUME, NULL);
>>> +		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;
>>>
>>
>>
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

Re: [PATCH v2 3/5] devfreq: add devfreq_suspend/resume() functions

[Chanwoo Choi]

Hi Lukasz,

On 2018년 12월 03일 23:31, Lukasz Luba wrote:
> This patch adds implementation for global suspend/resume for
> devfreq framework. System suspend will next use these functions.
> 
> The patch is based on earlier work by Tobias Jakobi.

Please remove it from each patch description.

> 
> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
> ---
>  drivers/devfreq/devfreq.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/devfreq.h   |  6 ++++++
>  2 files changed, 48 insertions(+)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 36bed24..7d60423 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -935,6 +935,48 @@ int devfreq_resume_device(struct devfreq *devfreq)
>  EXPORT_SYMBOL(devfreq_resume_device);
>  
>  /**
> + * devfreq_suspend() - Suspend devfreq governors and devices
> + *
> + * Called during system wide Suspend/Hibernate cycles for suspending governors
> + * and devices preserving the state for resume. On some platforms the devfreq
> + * device must have precise state (frequency) after resume in order to provide
> + * fully operating setup.
> + */
> +void devfreq_suspend(void)
> +{
> +	struct devfreq *devfreq;
> +	int ret;
> +
> +	mutex_lock(&devfreq_list_lock);
> +	list_for_each_entry(devfreq, &devfreq_list, node) {
> +		ret = devfreq_suspend_device(devfreq);
> +		if (ret)
> +			dev_warn(&devfreq->dev, "device suspend failed\n");

When I checked the cpufreq_suspend(), cpufreq_suspend() prints message as 'err' level.
I think that dev_err is more proper than dev_warn.

I'm not sure what is more correct log.
But, 'devfreq->dev' device has the separate suspend/resume function.
So, I think that devfreq_suspend() should print error log containing
that it is error by devfreq framework.

"device suspend failed"
-> "failed to suspend devfreq device"

> +	}
> +	mutex_unlock(&devfreq_list_lock);
> +}
> +
> +/**
> + * devfreq_resume() - Resume devfreq governors and devices
> + *
> + * Called during system wide Suspend/Hibernate cycle for resuming governors and
> + * devices that are suspended with devfreq_suspend().
> + */
> +void devfreq_resume(void)
> +{
> +	struct devfreq *devfreq;
> +	int ret;
> +
> +	mutex_lock(&devfreq_list_lock);
> +	list_for_each_entry(devfreq, &devfreq_list, node) {
> +		ret = devfreq_resume_device(devfreq);
> +		if (ret)
> +			dev_warn(&devfreq->dev, "device resume failed\n");

ditto.

"device resume failed"
-> "failed to resume devfreq device"


> +	}
> +	mutex_unlock(&devfreq_list_lock);
> +}
> +
> +/**
>   * devfreq_add_governor() - Add devfreq governor
>   * @governor:	the devfreq governor to be added
>   */
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index d985199..fbffa74 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -205,6 +205,9 @@ extern void devm_devfreq_remove_device(struct device *dev,
>  extern int devfreq_suspend_device(struct devfreq *devfreq);
>  extern int devfreq_resume_device(struct devfreq *devfreq);
>  
> +extern void devfreq_suspend(void);
> +extern void devfreq_resume(void);
> +
>  /**
>   * update_devfreq() - Reevaluate the device and configure frequency
>   * @devfreq:	the devfreq device
> @@ -331,6 +334,9 @@ static inline int devfreq_resume_device(struct devfreq *devfreq)
>  	return 0;
>  }
>  
> +static inline void devfreq_suspend(void) {}
> +static inline void devfreq_resume(void) {}
> +
>  static inline struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
>  					   unsigned long *freq, u32 flags)
>  {
> 

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

Re: [PATCH v2 1/5] devfreq: refactor set_target frequency function

[Lukasz Luba]

Hi Chanwoo,

On 12/4/18 5:39 AM, Chanwoo Choi wrote:
> Hi Lukasz,
> 
> On 2018년 12월 03일 23:31, Lukasz Luba wrote:
>> The refactoring is needed for the new client in devfreq: suspend.
>> To avoid code duplication, move it to the new local function
>> devfreq_set_target.
>>
>> The patch is based on earlier work by Tobias Jakobi.
> 
> As I already commented, Please remove it. You already mentioned it on cover-letter.
> If you want to contain the contribution history of Tobias, you might better
> to add 'Signed-off-by' or others.
OK

Regards,
Lukasz
> 
>>
>> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
>> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
>> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
>> ---
>>   drivers/devfreq/devfreq.c | 62 +++++++++++++++++++++++++++--------------------
>>   1 file changed, 36 insertions(+), 26 deletions(-)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index 1414130..a9fd61b 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -285,6 +285,40 @@ static int devfreq_notify_transition(struct devfreq *devfreq,
>>   	return 0;
>>   }
>>   
>> +static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
>> +			      u32 flags)
>> +{
>> +	struct devfreq_freqs freqs;
>> +	unsigned long cur_freq;
>> +	int err = 0;
>> +
>> +	if (devfreq->profile->get_cur_freq)
>> +		devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
>> +	else
>> +		cur_freq = devfreq->previous_freq;
>> +
>> +	freqs.old = cur_freq;
>> +	freqs.new = new_freq;
>> +	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
>> +
>> +	err = devfreq->profile->target(devfreq->dev.parent, &new_freq, flags);
>> +	if (err) {
>> +		freqs.new = cur_freq;
>> +		devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
>> +		return err;
>> +	}
>> +
>> +	freqs.new = new_freq;
>> +	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
>> +
>> +	if (devfreq_update_status(devfreq, new_freq))
>> +		dev_err(&devfreq->dev,
>> +			"Couldn't update frequency transition information.\n");
>> +
>> +	devfreq->previous_freq = new_freq;
>> +	return err;
>> +}
>> +
>>   /* Load monitoring helper functions for governors use */
>>   
>>   /**
>> @@ -296,8 +330,7 @@ static int devfreq_notify_transition(struct devfreq *devfreq,
>>    */
>>   int update_devfreq(struct devfreq *devfreq)
>>   {
>> -	struct devfreq_freqs freqs;
>> -	unsigned long freq, cur_freq, min_freq, max_freq;
>> +	unsigned long freq, min_freq, max_freq;
>>   	int err = 0;
>>   	u32 flags = 0;
>>   
>> @@ -333,31 +366,8 @@ int update_devfreq(struct devfreq *devfreq)
>>   		flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
>>   	}
>>   
>> -	if (devfreq->profile->get_cur_freq)
>> -		devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
>> -	else
>> -		cur_freq = devfreq->previous_freq;
>> -
>> -	freqs.old = cur_freq;
>> -	freqs.new = freq;
>> -	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
>> +	return devfreq_set_target(devfreq, freq, flags);
>>   
>> -	err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
>> -	if (err) {
>> -		freqs.new = cur_freq;
>> -		devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
>> -		return err;
>> -	}
>> -
>> -	freqs.new = freq;
>> -	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
>> -
>> -	if (devfreq_update_status(devfreq, freq))
>> -		dev_err(&devfreq->dev,
>> -			"Couldn't update frequency transition information.\n");
>> -
>> -	devfreq->previous_freq = freq;
>> -	return err;
>>   }
>>   EXPORT_SYMBOL(update_devfreq);
>>   
>>
> 
> 

Re: [PATCH v2 2/5] devfreq: add support for suspend/resume of a devfreq device

[Lukasz Luba]

Hi Chanwoo,

On 12/4/18 6:36 AM, Chanwoo Choi wrote:
> Hi Lukasz,
> 
> Looks good to me. But, I add the some comments.
> If you will fix it, feel free to add my tag:
> Reviewed-by: Chanwoo choi <cw00.choi@samsung.com>
> 
> On 2018년 12월 03일 23:31, Lukasz Luba wrote:
>> The patch prepares devfreq device for handling suspend/resume
>> functionality.  The new fields will store needed information during this
> 
> nitpick. Remove unneeded space. There are two spaces between '.' and 'The new'.
> 
>> process.  Devfreq framework handles opp-suspend DT entry and there is no
> 
> ditto.
> 
>> need of modyfications in the drivers code.  It uses atomic variables to
> 
> ditto.
> 
>> make sure no race condition affects the process.
>>
>> The patch is based on earlier work by Tobias Jakobi.
> 
> Please remove it from each patch description.
> 
Comments addressed in next v3 patch set. Thank you.

Regards,
Lukasz
>>
>> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
>> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
>> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
>> ---
>>   drivers/devfreq/devfreq.c | 51 +++++++++++++++++++++++++++++++++++++++--------
>>   include/linux/devfreq.h   |  7 +++++++
>>   2 files changed, 50 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index a9fd61b..36bed24 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)
>> -		return 0;
>> +	if (devfreq->governor) {
>> +		ret = devfreq->governor->event_handler(devfreq,
>> +					DEVFREQ_GOV_SUSPEND, NULL);
>> +		if (ret)
>> +			return ret;
>> +	}
>> +
>> +	if (devfreq->suspend_freq) {
>> +		if (atomic_inc_return(&devfreq->suspend_count) > 1)
>> +			return 0;
>> +
>> +		ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0);
>> +		if (ret)
>> +			return ret;
>> +	}
>>   
>> -	return devfreq->governor->event_handler(devfreq,
>> -				DEVFREQ_GOV_SUSPEND, NULL);
>> +	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)
>> -		return 0;
>> +	if (devfreq->resume_freq) {
>> +		if (atomic_dec_return(&devfreq->suspend_count) >= 1)
>> +			return 0;
>>   
>> -	return devfreq->governor->event_handler(devfreq,
>> -				DEVFREQ_GOV_RESUME, NULL);
>> +		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;
>>
> 
> 

Re: [PATCH v2 3/5] devfreq: add devfreq_suspend/resume() functions

[Lukasz Luba]

Hi Chanwoo,

On 12/4/18 7:19 AM, Chanwoo Choi wrote:
> Hi Lukasz,
> 
> On 2018년 12월 03일 23:31, Lukasz Luba wrote:
>> This patch adds implementation for global suspend/resume for
>> devfreq framework. System suspend will next use these functions.
>>
>> The patch is based on earlier work by Tobias Jakobi.
> 
> Please remove it from each patch description.
OK
> 
>>
>> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
>> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
>> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
>> ---
>>   drivers/devfreq/devfreq.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>>   include/linux/devfreq.h   |  6 ++++++
>>   2 files changed, 48 insertions(+)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index 36bed24..7d60423 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -935,6 +935,48 @@ int devfreq_resume_device(struct devfreq *devfreq)
>>   EXPORT_SYMBOL(devfreq_resume_device);
>>   
>>   /**
>> + * devfreq_suspend() - Suspend devfreq governors and devices
>> + *
>> + * Called during system wide Suspend/Hibernate cycles for suspending governors
>> + * and devices preserving the state for resume. On some platforms the devfreq
>> + * device must have precise state (frequency) after resume in order to provide
>> + * fully operating setup.
>> + */
>> +void devfreq_suspend(void)
>> +{
>> +	struct devfreq *devfreq;
>> +	int ret;
>> +
>> +	mutex_lock(&devfreq_list_lock);
>> +	list_for_each_entry(devfreq, &devfreq_list, node) {
>> +		ret = devfreq_suspend_device(devfreq);
>> +		if (ret)
>> +			dev_warn(&devfreq->dev, "device suspend failed\n");
> 
> When I checked the cpufreq_suspend(), cpufreq_suspend() prints message as 'err' level.
> I think that dev_err is more proper than dev_warn.
> 
> I'm not sure what is more correct log.
> But, 'devfreq->dev' device has the separate suspend/resume function.
> So, I think that devfreq_suspend() should print error log containing
> that it is error by devfreq framework.
> 
> "device suspend failed"
> -> "failed to suspend devfreq device"
OK, changed in next v3 patch set.
> 
>> +	}
>> +	mutex_unlock(&devfreq_list_lock);
>> +}
>> +
>> +/**
>> + * devfreq_resume() - Resume devfreq governors and devices
>> + *
>> + * Called during system wide Suspend/Hibernate cycle for resuming governors and
>> + * devices that are suspended with devfreq_suspend().
>> + */
>> +void devfreq_resume(void)
>> +{
>> +	struct devfreq *devfreq;
>> +	int ret;
>> +
>> +	mutex_lock(&devfreq_list_lock);
>> +	list_for_each_entry(devfreq, &devfreq_list, node) {
>> +		ret = devfreq_resume_device(devfreq);
>> +		if (ret)
>> +			dev_warn(&devfreq->dev, "device resume failed\n");
> 
> ditto.
> 
> "device resume failed"
> -> "failed to resume devfreq device"
> 
ACK

Regards,
Lukasz
> 
>> +	}
>> +	mutex_unlock(&devfreq_list_lock);
>> +}
>> +
>> +/**
>>    * devfreq_add_governor() - Add devfreq governor
>>    * @governor:	the devfreq governor to be added
>>    */
>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>> index d985199..fbffa74 100644
>> --- a/include/linux/devfreq.h
>> +++ b/include/linux/devfreq.h
>> @@ -205,6 +205,9 @@ extern void devm_devfreq_remove_device(struct device *dev,
>>   extern int devfreq_suspend_device(struct devfreq *devfreq);
>>   extern int devfreq_resume_device(struct devfreq *devfreq);
>>   
>> +extern void devfreq_suspend(void);
>> +extern void devfreq_resume(void);
>> +
>>   /**
>>    * update_devfreq() - Reevaluate the device and configure frequency
>>    * @devfreq:	the devfreq device
>> @@ -331,6 +334,9 @@ static inline int devfreq_resume_device(struct devfreq *devfreq)
>>   	return 0;
>>   }
>>   
>> +static inline void devfreq_suspend(void) {}
>> +static inline void devfreq_resume(void) {}
>> +
>>   static inline struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
>>   					   unsigned long *freq, u32 flags)
>>   {
>>
> 

Re: [PATCH v2 2/5] devfreq: add support for suspend/resume of a devfreq device

[Lukasz Luba]

Hi Chanwoo,

On 12/4/18 7:10 AM, Chanwoo Choi wrote:
> Hi Lukasz,
> 
> I add the comment about 'suspend_count'.
> 
> On 2018년 12월 04일 14:43, Chanwoo Choi wrote:
>> Hi,
>>
>> On 2018년 12월 04일 14:36, Chanwoo Choi wrote:
>>> Hi Lukasz,
>>>
>>> Looks good to me. But, I add the some comments.
>>> If you will fix it, feel free to add my tag:
>>> Reviewed-by: Chanwoo choi <cw00.choi@samsung.com>
>>
>> Sorry. Fix typo 'choi' to 'Choi' as following.
>> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
>>
>>>
>>> On 2018년 12월 03일 23:31, Lukasz Luba wrote:
>>>> The patch prepares devfreq device for handling suspend/resume
>>>> functionality.  The new fields will store needed information during this
>>>
>>> nitpick. Remove unneeded space. There are two spaces between '.' and 'The new'.
>>>
>>>> process.  Devfreq framework handles opp-suspend DT entry and there is no
>>>
>>> ditto.
>>>
>>>> need of modyfications in the drivers code.  It uses atomic variables to
>>>
>>> ditto.
>>>
>>>> make sure no race condition affects the process.
>>>>
>>>> The patch is based on earlier work by Tobias Jakobi.
>>>
>>> Please remove it from each patch description.
>>>
>>>>
>>>> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
>>>> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
>>>> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
>>>> ---
>>>>   drivers/devfreq/devfreq.c | 51 +++++++++++++++++++++++++++++++++++++++--------
>>>>   include/linux/devfreq.h   |  7 +++++++
>>>>   2 files changed, 50 insertions(+), 8 deletions(-)
>>>>
>>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>>> index a9fd61b..36bed24 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)
>>>> -		return 0;
>>>> +	if (devfreq->governor) {
>>>> +		ret = devfreq->governor->event_handler(devfreq,
>>>> +					DEVFREQ_GOV_SUSPEND, NULL);
>>>> +		if (ret)
>>>> +			return ret;
>>>> +	}
>>>> +
>>>> +	if (devfreq->suspend_freq) {
>>>> +		if (atomic_inc_return(&devfreq->suspend_count) > 1)
>>>> +			return 0;
>>>> +
>>>> +		ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0);
>>>> +		if (ret)
>>>> +			return ret;
>>>> +	}
> 
> In this patch, if some users call 'devfreq_suspend_device' twice,
> 'devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_SUSPEND, NULL)'
> is called twice but devfreq_set_target() is called only one.
> I knew that it is no problem for operation.
> 
> But,
> I think that you better to use 'suspend_count' as the reference count
> of devfreq_suspend/resume_device(). But, if you use 'suspend_count'
> in order to check whether this devfreq is suspended or not,
> we can reduce the unneeded redundant call when calling it twice.
> 
> clock and regulator used the 'reference count' method in order to
> remove the redundant call.

I think I've got the point. I will move the atomic check just
after the !devfreq check. Something like the code bellow is what you
would like to see?
---8<-----
if (!devfreq)
	return -EINVAL;
if (atomic_inc_return(&devfreq->suspend_count) > 1)
	return0;

---->8-------
> 
> 
>>>>   
>>>> -	return devfreq->governor->event_handler(devfreq,
>>>> -				DEVFREQ_GOV_SUSPEND, NULL);
>>>> +	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)
>>>> -		return 0;
>>>> +	if (devfreq->resume_freq) {
>>>> +		if (atomic_dec_return(&devfreq->suspend_count) >= 1)
>>>> +			return 0;
> 
> ditto.
Same approach here:
---8<-----
if (!devfreq)
	return -EINVAL;
if (atomic_dec_return(&devfreq->suspend_count) >= 1)
	return 0;
---->8-------

Regards,
Lukasz
> 
>>>>   
>>>> -	return devfreq->governor->event_handler(devfreq,
>>>> -				DEVFREQ_GOV_RESUME, NULL);
>>>> +		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;
>>>>
>>>
>>>
>>
>>
> 
> 

Re: [PATCH v2 2/5] devfreq: add support for suspend/resume of a devfreq device

[Chanwoo Choi]

Hi Lukasz,

On 2018년 12월 04일 18:53, Lukasz Luba wrote:
> Hi Chanwoo,
> 
> On 12/4/18 7:10 AM, Chanwoo Choi wrote:
>> Hi Lukasz,
>>
>> I add the comment about 'suspend_count'.
>>
>> On 2018년 12월 04일 14:43, Chanwoo Choi wrote:
>>> Hi,
>>>
>>> On 2018년 12월 04일 14:36, Chanwoo Choi wrote:
>>>> Hi Lukasz,
>>>>
>>>> Looks good to me. But, I add the some comments.
>>>> If you will fix it, feel free to add my tag:
>>>> Reviewed-by: Chanwoo choi <cw00.choi@samsung.com>
>>>
>>> Sorry. Fix typo 'choi' to 'Choi' as following.
>>> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
>>>
>>>>
>>>> On 2018년 12월 03일 23:31, Lukasz Luba wrote:
>>>>> The patch prepares devfreq device for handling suspend/resume
>>>>> functionality.  The new fields will store needed information during this
>>>>
>>>> nitpick. Remove unneeded space. There are two spaces between '.' and 'The new'.
>>>>
>>>>> process.  Devfreq framework handles opp-suspend DT entry and there is no
>>>>
>>>> ditto.
>>>>
>>>>> need of modyfications in the drivers code.  It uses atomic variables to
>>>>
>>>> ditto.
>>>>
>>>>> make sure no race condition affects the process.
>>>>>
>>>>> The patch is based on earlier work by Tobias Jakobi.
>>>>
>>>> Please remove it from each patch description.
>>>>
>>>>>
>>>>> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
>>>>> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
>>>>> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
>>>>> ---
>>>>>   drivers/devfreq/devfreq.c | 51 +++++++++++++++++++++++++++++++++++++++--------
>>>>>   include/linux/devfreq.h   |  7 +++++++
>>>>>   2 files changed, 50 insertions(+), 8 deletions(-)
>>>>>
>>>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>>>> index a9fd61b..36bed24 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)
>>>>> -		return 0;
>>>>> +	if (devfreq->governor) {
>>>>> +		ret = devfreq->governor->event_handler(devfreq,
>>>>> +					DEVFREQ_GOV_SUSPEND, NULL);
>>>>> +		if (ret)
>>>>> +			return ret;
>>>>> +	}
>>>>> +
>>>>> +	if (devfreq->suspend_freq) {
>>>>> +		if (atomic_inc_return(&devfreq->suspend_count) > 1)
>>>>> +			return 0;
>>>>> +
>>>>> +		ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0);
>>>>> +		if (ret)
>>>>> +			return ret;
>>>>> +	}
>>
>> In this patch, if some users call 'devfreq_suspend_device' twice,
>> 'devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_SUSPEND, NULL)'
>> is called twice but devfreq_set_target() is called only one.
>> I knew that it is no problem for operation.
>>
>> But,
>> I think that you better to use 'suspend_count' as the reference count
>> of devfreq_suspend/resume_device(). But, if you use 'suspend_count'
>> in order to check whether this devfreq is suspended or not,
>> we can reduce the unneeded redundant call when calling it twice.
>>
>> clock and regulator used the 'reference count' method in order to
>> remove the redundant call.
> 
> I think I've got the point. I will move the atomic check just
> after the !devfreq check. Something like the code bellow is what you
> would like to see?
> ---8<-----
> if (!devfreq)
> 	return -EINVAL;
> if (atomic_inc_return(&devfreq->suspend_count) > 1)
> 	return0;

Looks good to me. I agree.

> 
> ---->8-------
>>
>>
>>>>>   
>>>>> -	return devfreq->governor->event_handler(devfreq,
>>>>> -				DEVFREQ_GOV_SUSPEND, NULL);
>>>>> +	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)
>>>>> -		return 0;
>>>>> +	if (devfreq->resume_freq) {
>>>>> +		if (atomic_dec_return(&devfreq->suspend_count) >= 1)
>>>>> +			return 0;
>>
>> ditto.
> Same approach here:
> ---8<-----
> if (!devfreq)
> 	return -EINVAL;
> if (atomic_dec_return(&devfreq->suspend_count) >= 1)
> 	return 0;

Looks good to me.

> ---->8-------
> 
> Regards,
> Lukasz
>>
>>>>>   
>>>>> -	return devfreq->governor->event_handler(devfreq,
>>>>> -				DEVFREQ_GOV_RESUME, NULL);
>>>>> +		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;
>>>>>
>>>>
>>>>
>>>
>>>
>>
>>
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

Re: [PATCH v2 2/5] devfreq: add support for suspend/resume of a devfreq device

[Lukasz Luba]

Hi Chanwoo,

On 12/5/18 1:09 AM, Chanwoo Choi wrote:
> Hi Lukasz,
> 
> On 2018년 12월 04일 18:53, Lukasz Luba wrote:
>> Hi Chanwoo,
>>
>> On 12/4/18 7:10 AM, Chanwoo Choi wrote:
>>> Hi Lukasz,
>>>
>>> I add the comment about 'suspend_count'.
>>>
>>> On 2018년 12월 04일 14:43, Chanwoo Choi wrote:
>>>> Hi,
>>>>
>>>> On 2018년 12월 04일 14:36, Chanwoo Choi wrote:
>>>>> Hi Lukasz,
>>>>>
>>>>> Looks good to me. But, I add the some comments.
>>>>> If you will fix it, feel free to add my tag:
>>>>> Reviewed-by: Chanwoo choi <cw00.choi@samsung.com>
>>>>
>>>> Sorry. Fix typo 'choi' to 'Choi' as following.
>>>> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
>>>>
>>>>>
>>>>> On 2018년 12월 03일 23:31, Lukasz Luba wrote:
>>>>>> The patch prepares devfreq device for handling suspend/resume
>>>>>> functionality.  The new fields will store needed information during this
>>>>>
>>>>> nitpick. Remove unneeded space. There are two spaces between '.' and 'The new'.
>>>>>
>>>>>> process.  Devfreq framework handles opp-suspend DT entry and there is no
>>>>>
>>>>> ditto.
>>>>>
>>>>>> need of modyfications in the drivers code.  It uses atomic variables to
>>>>>
>>>>> ditto.
>>>>>
>>>>>> make sure no race condition affects the process.
>>>>>>
>>>>>> The patch is based on earlier work by Tobias Jakobi.
>>>>>
>>>>> Please remove it from each patch description.
>>>>>
>>>>>>
>>>>>> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
>>>>>> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
>>>>>> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
>>>>>> ---
>>>>>>    drivers/devfreq/devfreq.c | 51 +++++++++++++++++++++++++++++++++++++++--------
>>>>>>    include/linux/devfreq.h   |  7 +++++++
>>>>>>    2 files changed, 50 insertions(+), 8 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>>>>> index a9fd61b..36bed24 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)
>>>>>> -		return 0;
>>>>>> +	if (devfreq->governor) {
>>>>>> +		ret = devfreq->governor->event_handler(devfreq,
>>>>>> +					DEVFREQ_GOV_SUSPEND, NULL);
>>>>>> +		if (ret)
>>>>>> +			return ret;
>>>>>> +	}
>>>>>> +
>>>>>> +	if (devfreq->suspend_freq) {
>>>>>> +		if (atomic_inc_return(&devfreq->suspend_count) > 1)
>>>>>> +			return 0;
>>>>>> +
>>>>>> +		ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0);
>>>>>> +		if (ret)
>>>>>> +			return ret;
>>>>>> +	}
>>>
>>> In this patch, if some users call 'devfreq_suspend_device' twice,
>>> 'devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_SUSPEND, NULL)'
>>> is called twice but devfreq_set_target() is called only one.
>>> I knew that it is no problem for operation.
>>>
>>> But,
>>> I think that you better to use 'suspend_count' as the reference count
>>> of devfreq_suspend/resume_device(). But, if you use 'suspend_count'
>>> in order to check whether this devfreq is suspended or not,
>>> we can reduce the unneeded redundant call when calling it twice.
>>>
>>> clock and regulator used the 'reference count' method in order to
>>> remove the redundant call.
>>
>> I think I've got the point. I will move the atomic check just
>> after the !devfreq check. Something like the code bellow is what you
>> would like to see?
>> ---8<-----
>> if (!devfreq)
>> 	return -EINVAL;
>> if (atomic_inc_return(&devfreq->suspend_count) > 1)
>> 	return0;
> 
> Looks good to me. I agree.
OK
> 
>>
>> ---->8-------
>>>
>>>
>>>>>>    
>>>>>> -	return devfreq->governor->event_handler(devfreq,
>>>>>> -				DEVFREQ_GOV_SUSPEND, NULL);
>>>>>> +	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)
>>>>>> -		return 0;
>>>>>> +	if (devfreq->resume_freq) {
>>>>>> +		if (atomic_dec_return(&devfreq->suspend_count) >= 1)
>>>>>> +			return 0;
>>>
>>> ditto.
>> Same approach here:
>> ---8<-----
>> if (!devfreq)
>> 	return -EINVAL;
>> if (atomic_dec_return(&devfreq->suspend_count) >= 1)
>> 	return 0;
> 
> Looks good to me.
Thank you. The patch set v3 is going to be sent.

Regards,
Lukasz

> 
>> ---->8-------
>>
>> Regards,
>> Lukasz
>>>
>>>>>>    
>>>>>> -	return devfreq->governor->event_handler(devfreq,
>>>>>> -				DEVFREQ_GOV_RESUME, NULL);
>>>>>> +		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;
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
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> 
> 

Re: [PATCH v2 2/5] devfreq: add support for suspend/resume of a devfreq device

[Pavel Machek]

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On Tue 2018-12-04 14:36:11, Chanwoo Choi wrote:
> Hi Lukasz,
> 
> Looks good to me. But, I add the some comments.
> If you will fix it, feel free to add my tag:
> Reviewed-by: Chanwoo choi <cw00.choi@samsung.com>
> 
> On 2018년 12월 03일 23:31, Lukasz Luba wrote:
> > The patch prepares devfreq device for handling suspend/resume
> > functionality.  The new fields will store needed information during this
> 
> nitpick. Remove unneeded space. There are two spaces between '.' and 'The new'. 

Yes. And that's because two spaces are okay at that place.

https://www.writersdigest.com/online-editor/how-many-spaces-after-a-period

Please don't cause unneeded noise on the list with trivial
comments. If the patch is okay, apply the patch, no need to find
trivial nit everywhere.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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