[PATCH v3 0/3] cpufreq-dt: add suspend frequency support

[PATCH v3 0/3] cpufreq-dt: add suspend frequency support

[Bartlomiej Zolnierkiewicz]

Hi,

This patch series adds suspend frequency support (using opp-v2
bindings and suspend-opp functionality) to cpufreq-dt driver and
then adds suspend opp for Exynos4412 based boards.

This patch series fixes suspend/resume support on Exynos4412
based Trats2 board and reboot hang on Exynos4412 based Odroid
U3 board.

Changes since v2:
- rewrited to use suspend-opp functionality

Changes since v1:
- removed superfluous ";"

Depends on:
- next-20150902 branch of linux-next kernel tree

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics


Bartlomiej Zolnierkiewicz (3):
  PM / OPP: add dev_pm_opp_get_suspend_opp() helper
  cpufreq-dt: add suspend frequency support
  ARM: dts: add suspend opp to exynos4412

 arch/arm/boot/dts/exynos4412.dtsi |  1 +
 drivers/base/power/opp.c          | 28 ++++++++++++++++++++++++++++
 drivers/cpufreq/cpufreq-dt.c      | 32 ++++++++++++++++++++++++++++++++
 include/linux/pm_opp.h            |  6 ++++++
 4 files changed, 67 insertions(+)

-- 
1.9.1

[PATCH v3 0/3] cpufreq-dt: add suspend frequency support

[Bartlomiej Zolnierkiewicz]

Hi,

This patch series adds suspend frequency support (using opp-v2
bindings and suspend-opp functionality) to cpufreq-dt driver and
then adds suspend opp for Exynos4412 based boards.

This patch series fixes suspend/resume support on Exynos4412
based Trats2 board and reboot hang on Exynos4412 based Odroid
U3 board.

Changes since v2:
- rewrited to use suspend-opp functionality

Changes since v1:
- removed superfluous ";"

Depends on:
- next-20150902 branch of linux-next kernel tree

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics


Bartlomiej Zolnierkiewicz (3):
  PM / OPP: add dev_pm_opp_get_suspend_opp() helper
  cpufreq-dt: add suspend frequency support
  ARM: dts: add suspend opp to exynos4412

 arch/arm/boot/dts/exynos4412.dtsi |  1 +
 drivers/base/power/opp.c          | 28 ++++++++++++++++++++++++++++
 drivers/cpufreq/cpufreq-dt.c      | 32 ++++++++++++++++++++++++++++++++
 include/linux/pm_opp.h            |  6 ++++++
 4 files changed, 67 insertions(+)

-- 
1.9.1

[PATCH v3 1/3] PM / OPP: add dev_pm_opp_get_suspend_opp() helper

[Bartlomiej Zolnierkiewicz]

Add dev_pm_opp_get_suspend_opp() helper to obtain suspend opp.

Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Thomas Abraham <thomas.ab@samsung.com>
Cc: Javier Martinez Canillas <javier@osg.samsung.com>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
---
 drivers/base/power/opp.c | 28 ++++++++++++++++++++++++++++
 include/linux/pm_opp.h   |  6 ++++++
 2 files changed, 34 insertions(+)

diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index eb25449..eaafca7 100644
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -341,6 +341,34 @@ unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev)
 EXPORT_SYMBOL_GPL(dev_pm_opp_get_max_clock_latency);
 
 /**
+ * dev_pm_opp_get_suspend_opp() - Get suspend opp
+ * @dev:	device for which we do this operation
+ *
+ * Return: This function returns pointer to the suspend opp if it is
+ * defined, otherwise it returns NULL.
+ *
+ * Locking: This function takes rcu_read_lock().
+ */
+struct dev_pm_opp *dev_pm_opp_get_suspend_opp(struct device *dev)
+{
+	struct device_opp *dev_opp;
+	struct dev_pm_opp *suspend_opp;
+
+	rcu_read_lock();
+
+	dev_opp = _find_device_opp(dev);
+	if (IS_ERR(dev_opp))
+		suspend_opp = NULL;
+	else
+		suspend_opp = dev_opp->suspend_opp;
+
+	rcu_read_unlock();
+
+	return suspend_opp;
+}
+EXPORT_SYMBOL_GPL(dev_pm_opp_get_suspend_opp);
+
+/**
  * dev_pm_opp_get_opp_count() - Get number of opps available in the opp list
  * @dev:	device for which we do this operation
  *
diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index cab7ba5..e817722 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -34,6 +34,7 @@ bool dev_pm_opp_is_turbo(struct dev_pm_opp *opp);
 
 int dev_pm_opp_get_opp_count(struct device *dev);
 unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev);
+struct dev_pm_opp *dev_pm_opp_get_suspend_opp(struct device *dev);
 
 struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev,
 					      unsigned long freq,
@@ -80,6 +81,11 @@ static inline unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev)
 	return 0;
 }
 
+static inline struct dev_pm_opp *dev_pm_opp_get_suspend_opp(struct device *dev)
+{
+	return NULL;
+}
+
 static inline struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev,
 					unsigned long freq, bool available)
 {
-- 
1.9.1

[PATCH v3 1/3] PM / OPP: add dev_pm_opp_get_suspend_opp() helper

[Bartlomiej Zolnierkiewicz]

Add dev_pm_opp_get_suspend_opp() helper to obtain suspend opp.

Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Thomas Abraham <thomas.ab@samsung.com>
Cc: Javier Martinez Canillas <javier@osg.samsung.com>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
---
 drivers/base/power/opp.c | 28 ++++++++++++++++++++++++++++
 include/linux/pm_opp.h   |  6 ++++++
 2 files changed, 34 insertions(+)

diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index eb25449..eaafca7 100644
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -341,6 +341,34 @@ unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev)
 EXPORT_SYMBOL_GPL(dev_pm_opp_get_max_clock_latency);
 
 /**
+ * dev_pm_opp_get_suspend_opp() - Get suspend opp
+ * @dev:	device for which we do this operation
+ *
+ * Return: This function returns pointer to the suspend opp if it is
+ * defined, otherwise it returns NULL.
+ *
+ * Locking: This function takes rcu_read_lock().
+ */
+struct dev_pm_opp *dev_pm_opp_get_suspend_opp(struct device *dev)
+{
+	struct device_opp *dev_opp;
+	struct dev_pm_opp *suspend_opp;
+
+	rcu_read_lock();
+
+	dev_opp = _find_device_opp(dev);
+	if (IS_ERR(dev_opp))
+		suspend_opp = NULL;
+	else
+		suspend_opp = dev_opp->suspend_opp;
+
+	rcu_read_unlock();
+
+	return suspend_opp;
+}
+EXPORT_SYMBOL_GPL(dev_pm_opp_get_suspend_opp);
+
+/**
  * dev_pm_opp_get_opp_count() - Get number of opps available in the opp list
  * @dev:	device for which we do this operation
  *
diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index cab7ba5..e817722 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -34,6 +34,7 @@ bool dev_pm_opp_is_turbo(struct dev_pm_opp *opp);
 
 int dev_pm_opp_get_opp_count(struct device *dev);
 unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev);
+struct dev_pm_opp *dev_pm_opp_get_suspend_opp(struct device *dev);
 
 struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev,
 					      unsigned long freq,
@@ -80,6 +81,11 @@ static inline unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev)
 	return 0;
 }
 
+static inline struct dev_pm_opp *dev_pm_opp_get_suspend_opp(struct device *dev)
+{
+	return NULL;
+}
+
 static inline struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev,
 					unsigned long freq, bool available)
 {
-- 
1.9.1

[PATCH v3 2/3] cpufreq-dt: add suspend frequency support

[Bartlomiej Zolnierkiewicz]

Add suspend frequency support and if needed set it to
the frequency obtained from the suspend opp (can be defined
using opp-v2 bindings and is optional).  Also implement
custom suspend method (needed to not error out on platforms
which don't require suspend frequency).

Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Thomas Abraham <thomas.ab@samsung.com>
Cc: Javier Martinez Canillas <javier@osg.samsung.com>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
---
 drivers/cpufreq/cpufreq-dt.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
index c3583cd..ba4ca85 100644
--- a/drivers/cpufreq/cpufreq-dt.c
+++ b/drivers/cpufreq/cpufreq-dt.c
@@ -196,6 +196,7 @@ static int cpufreq_init(struct cpufreq_policy *policy)
 	struct device *cpu_dev;
 	struct regulator *cpu_reg;
 	struct clk *cpu_clk;
+	struct dev_pm_opp *suspend_opp;
 	unsigned long min_uV = ~0, max_uV = 0;
 	unsigned int transition_latency;
 	bool need_update = false;
@@ -329,6 +330,11 @@ static int cpufreq_init(struct cpufreq_policy *policy)
 	policy->driver_data = priv;
 
 	policy->clk = cpu_clk;
+
+	suspend_opp = dev_pm_opp_get_suspend_opp(cpu_dev);
+	if (suspend_opp)
+		policy->suspend_freq = dev_pm_opp_get_freq(suspend_opp) / 1000;
+
 	ret = cpufreq_table_validate_and_show(policy, freq_table);
 	if (ret) {
 		dev_err(cpu_dev, "%s: invalid frequency table: %d\n", __func__,
@@ -409,6 +415,31 @@ static void cpufreq_ready(struct cpufreq_policy *policy)
 	of_node_put(np);
 }
 
+#ifdef CONFIG_PM
+static int cpufreq_dt_suspend(struct cpufreq_policy *policy)
+{
+	int ret;
+
+	if (!policy->suspend_freq) {
+		pr_debug("%s: suspend_freq not defined\n", __func__);
+		return 0;
+	}
+
+	pr_debug("%s: Setting suspend-freq: %u\n", __func__,
+			policy->suspend_freq);
+
+	ret = __cpufreq_driver_target(policy, policy->suspend_freq,
+			CPUFREQ_RELATION_H);
+	if (ret)
+		pr_err("%s: unable to set suspend-freq: %u. err: %d\n",
+				__func__, policy->suspend_freq, ret);
+
+	return ret;
+}
+#else
+#define cpufreq_dt_suspend NULL
+#endif
+
 static struct cpufreq_driver dt_cpufreq_driver = {
 	.flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 	.verify = cpufreq_generic_frequency_table_verify,
@@ -419,6 +450,7 @@ static struct cpufreq_driver dt_cpufreq_driver = {
 	.ready = cpufreq_ready,
 	.name = "cpufreq-dt",
 	.attr = cpufreq_dt_attr,
+	.suspend = cpufreq_dt_suspend,
 };
 
 static int dt_cpufreq_probe(struct platform_device *pdev)
-- 
1.9.1

[PATCH v3 2/3] cpufreq-dt: add suspend frequency support

[Bartlomiej Zolnierkiewicz]

Add suspend frequency support and if needed set it to
the frequency obtained from the suspend opp (can be defined
using opp-v2 bindings and is optional).  Also implement
custom suspend method (needed to not error out on platforms
which don't require suspend frequency).

Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Thomas Abraham <thomas.ab@samsung.com>
Cc: Javier Martinez Canillas <javier@osg.samsung.com>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
---
 drivers/cpufreq/cpufreq-dt.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
index c3583cd..ba4ca85 100644
--- a/drivers/cpufreq/cpufreq-dt.c
+++ b/drivers/cpufreq/cpufreq-dt.c
@@ -196,6 +196,7 @@ static int cpufreq_init(struct cpufreq_policy *policy)
 	struct device *cpu_dev;
 	struct regulator *cpu_reg;
 	struct clk *cpu_clk;
+	struct dev_pm_opp *suspend_opp;
 	unsigned long min_uV = ~0, max_uV = 0;
 	unsigned int transition_latency;
 	bool need_update = false;
@@ -329,6 +330,11 @@ static int cpufreq_init(struct cpufreq_policy *policy)
 	policy->driver_data = priv;
 
 	policy->clk = cpu_clk;
+
+	suspend_opp = dev_pm_opp_get_suspend_opp(cpu_dev);
+	if (suspend_opp)
+		policy->suspend_freq = dev_pm_opp_get_freq(suspend_opp) / 1000;
+
 	ret = cpufreq_table_validate_and_show(policy, freq_table);
 	if (ret) {
 		dev_err(cpu_dev, "%s: invalid frequency table: %d\n", __func__,
@@ -409,6 +415,31 @@ static void cpufreq_ready(struct cpufreq_policy *policy)
 	of_node_put(np);
 }
 
+#ifdef CONFIG_PM
+static int cpufreq_dt_suspend(struct cpufreq_policy *policy)
+{
+	int ret;
+
+	if (!policy->suspend_freq) {
+		pr_debug("%s: suspend_freq not defined\n", __func__);
+		return 0;
+	}
+
+	pr_debug("%s: Setting suspend-freq: %u\n", __func__,
+			policy->suspend_freq);
+
+	ret = __cpufreq_driver_target(policy, policy->suspend_freq,
+			CPUFREQ_RELATION_H);
+	if (ret)
+		pr_err("%s: unable to set suspend-freq: %u. err: %d\n",
+				__func__, policy->suspend_freq, ret);
+
+	return ret;
+}
+#else
+#define cpufreq_dt_suspend NULL
+#endif
+
 static struct cpufreq_driver dt_cpufreq_driver = {
 	.flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 	.verify = cpufreq_generic_frequency_table_verify,
@@ -419,6 +450,7 @@ static struct cpufreq_driver dt_cpufreq_driver = {
 	.ready = cpufreq_ready,
 	.name = "cpufreq-dt",
 	.attr = cpufreq_dt_attr,
+	.suspend = cpufreq_dt_suspend,
 };
 
 static int dt_cpufreq_probe(struct platform_device *pdev)
-- 
1.9.1

[PATCH v3 3/3] ARM: dts: add suspend opp to exynos4412

[Bartlomiej Zolnierkiewicz]

Mark 800MHz OPP as a suspend opp for Exynos4412 based
boards so effectively cpufreq-dt driver behavior w.r.t.
suspend frequency matches what the old exynos-cpufreq
driver has been doing.

This patch fixes suspend/resume support on Exynos4412 based
Trats2 board and reboot hang on Exynos4412 based Odroid U3
board.

Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Thomas Abraham <thomas.ab@samsung.com>
Cc: Javier Martinez Canillas <javier@osg.samsung.com>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
---
 arch/arm/boot/dts/exynos4412.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/boot/dts/exynos4412.dtsi b/arch/arm/boot/dts/exynos4412.dtsi
index ca0e3c1..294cfe4 100644
--- a/arch/arm/boot/dts/exynos4412.dtsi
+++ b/arch/arm/boot/dts/exynos4412.dtsi
@@ -98,6 +98,7 @@
 			opp-hz = /bits/ 64 <800000000>;
 			opp-microvolt = <1000000>;
 			clock-latency-ns = <200000>;
+			opp-suspend;
 		};
 		opp07 {
 			opp-hz = /bits/ 64 <900000000>;
-- 
1.9.1

[PATCH v3 3/3] ARM: dts: add suspend opp to exynos4412

[Bartlomiej Zolnierkiewicz]

Mark 800MHz OPP as a suspend opp for Exynos4412 based
boards so effectively cpufreq-dt driver behavior w.r.t.
suspend frequency matches what the old exynos-cpufreq
driver has been doing.

This patch fixes suspend/resume support on Exynos4412 based
Trats2 board and reboot hang on Exynos4412 based Odroid U3
board.

Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Thomas Abraham <thomas.ab@samsung.com>
Cc: Javier Martinez Canillas <javier@osg.samsung.com>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
---
 arch/arm/boot/dts/exynos4412.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/boot/dts/exynos4412.dtsi b/arch/arm/boot/dts/exynos4412.dtsi
index ca0e3c1..294cfe4 100644
--- a/arch/arm/boot/dts/exynos4412.dtsi
+++ b/arch/arm/boot/dts/exynos4412.dtsi
@@ -98,6 +98,7 @@
 			opp-hz = /bits/ 64 <800000000>;
 			opp-microvolt = <1000000>;
 			clock-latency-ns = <200000>;
+			opp-suspend;
 		};
 		opp07 {
 			opp-hz = /bits/ 64 <900000000>;
-- 
1.9.1

Re: [PATCH v3 1/3] PM / OPP: add dev_pm_opp_get_suspend_opp() helper

[Viresh Kumar]

On 03-09-15, 20:11, Bartlomiej Zolnierkiewicz wrote:
> Add dev_pm_opp_get_suspend_opp() helper to obtain suspend opp.
> 
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Cc: Thomas Abraham <thomas.ab@samsung.com>
> Cc: Javier Martinez Canillas <javier@osg.samsung.com>
> Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
> Cc: Marek Szyprowski <m.szyprowski@samsung.com>
> Cc: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> ---
>  drivers/base/power/opp.c | 28 ++++++++++++++++++++++++++++
>  include/linux/pm_opp.h   |  6 ++++++
>  2 files changed, 34 insertions(+)
> 
> diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
> index eb25449..eaafca7 100644
> --- a/drivers/base/power/opp.c
> +++ b/drivers/base/power/opp.c
> @@ -341,6 +341,34 @@ unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev)
>  EXPORT_SYMBOL_GPL(dev_pm_opp_get_max_clock_latency);
>  
>  /**
> + * dev_pm_opp_get_suspend_opp() - Get suspend opp
> + * @dev:	device for which we do this operation
> + *
> + * Return: This function returns pointer to the suspend opp if it is
> + * defined, otherwise it returns NULL.
> + *
> + * Locking: This function takes rcu_read_lock().
> + */
> +struct dev_pm_opp *dev_pm_opp_get_suspend_opp(struct device *dev)
> +{
> +	struct device_opp *dev_opp;
> +	struct dev_pm_opp *suspend_opp;
> +
> +	rcu_read_lock();

This is wrong. Please have a look at other exported APIs that return
an OPP. RCU protected structures must be accessed from within RCU
locks _ONLY_. But your function returns the pointer after dropping
the locks. Which essentially means that the OPP can be freed by core,
by the time you start using it. :)

So, in such cases, its upto the caller to ensure that locks are taken
properly.

You can look at dev_pm_opp_find_freq_exact() as an example.

-- 
viresh

[PATCH v3 1/3] PM / OPP: add dev_pm_opp_get_suspend_opp() helper

[Viresh Kumar]

On 03-09-15, 20:11, Bartlomiej Zolnierkiewicz wrote:
> Add dev_pm_opp_get_suspend_opp() helper to obtain suspend opp.
> 
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Cc: Thomas Abraham <thomas.ab@samsung.com>
> Cc: Javier Martinez Canillas <javier@osg.samsung.com>
> Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
> Cc: Marek Szyprowski <m.szyprowski@samsung.com>
> Cc: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> ---
>  drivers/base/power/opp.c | 28 ++++++++++++++++++++++++++++
>  include/linux/pm_opp.h   |  6 ++++++
>  2 files changed, 34 insertions(+)
> 
> diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
> index eb25449..eaafca7 100644
> --- a/drivers/base/power/opp.c
> +++ b/drivers/base/power/opp.c
> @@ -341,6 +341,34 @@ unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev)
>  EXPORT_SYMBOL_GPL(dev_pm_opp_get_max_clock_latency);
>  
>  /**
> + * dev_pm_opp_get_suspend_opp() - Get suspend opp
> + * @dev:	device for which we do this operation
> + *
> + * Return: This function returns pointer to the suspend opp if it is
> + * defined, otherwise it returns NULL.
> + *
> + * Locking: This function takes rcu_read_lock().
> + */
> +struct dev_pm_opp *dev_pm_opp_get_suspend_opp(struct device *dev)
> +{
> +	struct device_opp *dev_opp;
> +	struct dev_pm_opp *suspend_opp;
> +
> +	rcu_read_lock();

This is wrong. Please have a look at other exported APIs that return
an OPP. RCU protected structures must be accessed from within RCU
locks _ONLY_. But your function returns the pointer after dropping
the locks. Which essentially means that the OPP can be freed by core,
by the time you start using it. :)

So, in such cases, its upto the caller to ensure that locks are taken
properly.

You can look at dev_pm_opp_find_freq_exact() as an example.

-- 
viresh

Re: [PATCH v3 2/3] cpufreq-dt: add suspend frequency support

[Viresh Kumar]

On 03-09-15, 20:11, Bartlomiej Zolnierkiewicz wrote:
> Add suspend frequency support and if needed set it to
> the frequency obtained from the suspend opp (can be defined
> using opp-v2 bindings and is optional).  Also implement
> custom suspend method (needed to not error out on platforms
> which don't require suspend frequency).
> 
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Cc: Thomas Abraham <thomas.ab@samsung.com>
> Cc: Javier Martinez Canillas <javier@osg.samsung.com>
> Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
> Cc: Marek Szyprowski <m.szyprowski@samsung.com>
> Cc: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> ---
>  drivers/cpufreq/cpufreq-dt.c | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
> +#ifdef CONFIG_PM
> +static int cpufreq_dt_suspend(struct cpufreq_policy *policy)
> +{
> +	int ret;
> +
> +	if (!policy->suspend_freq) {
> +		pr_debug("%s: suspend_freq not defined\n", __func__);
> +		return 0;
> +	}
> +
> +	pr_debug("%s: Setting suspend-freq: %u\n", __func__,
> +			policy->suspend_freq);
> +
> +	ret = __cpufreq_driver_target(policy, policy->suspend_freq,
> +			CPUFREQ_RELATION_H);
> +	if (ret)
> +		pr_err("%s: unable to set suspend-freq: %u. err: %d\n",
> +				__func__, policy->suspend_freq, ret);
> +
> +	return ret;
> +}
> +#else
> +#define cpufreq_dt_suspend NULL
> +#endif

No, there is no point replicating the exactly same routine again.
Rather modify cpufreq_generic_suspend() to not print error and instead
do pr_debug(), on !policy->suspend_freq.

-- 
viresh

[PATCH v3 2/3] cpufreq-dt: add suspend frequency support

[Viresh Kumar]

On 03-09-15, 20:11, Bartlomiej Zolnierkiewicz wrote:
> Add suspend frequency support and if needed set it to
> the frequency obtained from the suspend opp (can be defined
> using opp-v2 bindings and is optional).  Also implement
> custom suspend method (needed to not error out on platforms
> which don't require suspend frequency).
> 
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Cc: Thomas Abraham <thomas.ab@samsung.com>
> Cc: Javier Martinez Canillas <javier@osg.samsung.com>
> Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
> Cc: Marek Szyprowski <m.szyprowski@samsung.com>
> Cc: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> ---
>  drivers/cpufreq/cpufreq-dt.c | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
> +#ifdef CONFIG_PM
> +static int cpufreq_dt_suspend(struct cpufreq_policy *policy)
> +{
> +	int ret;
> +
> +	if (!policy->suspend_freq) {
> +		pr_debug("%s: suspend_freq not defined\n", __func__);
> +		return 0;
> +	}
> +
> +	pr_debug("%s: Setting suspend-freq: %u\n", __func__,
> +			policy->suspend_freq);
> +
> +	ret = __cpufreq_driver_target(policy, policy->suspend_freq,
> +			CPUFREQ_RELATION_H);
> +	if (ret)
> +		pr_err("%s: unable to set suspend-freq: %u. err: %d\n",
> +				__func__, policy->suspend_freq, ret);
> +
> +	return ret;
> +}
> +#else
> +#define cpufreq_dt_suspend NULL
> +#endif

No, there is no point replicating the exactly same routine again.
Rather modify cpufreq_generic_suspend() to not print error and instead
do pr_debug(), on !policy->suspend_freq.

-- 
viresh

Re: [PATCH v3 3/3] ARM: dts: add suspend opp to exynos4412

[Viresh Kumar]

On 03-09-15, 20:11, Bartlomiej Zolnierkiewicz wrote:
> Mark 800MHz OPP as a suspend opp for Exynos4412 based
> boards so effectively cpufreq-dt driver behavior w.r.t.
> suspend frequency matches what the old exynos-cpufreq
> driver has been doing.
> 
> This patch fixes suspend/resume support on Exynos4412 based
> Trats2 board and reboot hang on Exynos4412 based Odroid U3
> board.
> 
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Cc: Thomas Abraham <thomas.ab@samsung.com>
> Cc: Javier Martinez Canillas <javier@osg.samsung.com>
> Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
> Cc: Marek Szyprowski <m.szyprowski@samsung.com>
> Cc: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> ---
>  arch/arm/boot/dts/exynos4412.dtsi | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm/boot/dts/exynos4412.dtsi b/arch/arm/boot/dts/exynos4412.dtsi
> index ca0e3c1..294cfe4 100644
> --- a/arch/arm/boot/dts/exynos4412.dtsi
> +++ b/arch/arm/boot/dts/exynos4412.dtsi
> @@ -98,6 +98,7 @@
>  			opp-hz = /bits/ 64 <800000000>;
>  			opp-microvolt = <1000000>;
>  			clock-latency-ns = <200000>;
> +			opp-suspend;
>  		};
>  		opp07 {
>  			opp-hz = /bits/ 64 <900000000>;

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

-- 
viresh

[PATCH v3 3/3] ARM: dts: add suspend opp to exynos4412

[Viresh Kumar]

On 03-09-15, 20:11, Bartlomiej Zolnierkiewicz wrote:
> Mark 800MHz OPP as a suspend opp for Exynos4412 based
> boards so effectively cpufreq-dt driver behavior w.r.t.
> suspend frequency matches what the old exynos-cpufreq
> driver has been doing.
> 
> This patch fixes suspend/resume support on Exynos4412 based
> Trats2 board and reboot hang on Exynos4412 based Odroid U3
> board.
> 
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Cc: Thomas Abraham <thomas.ab@samsung.com>
> Cc: Javier Martinez Canillas <javier@osg.samsung.com>
> Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
> Cc: Marek Szyprowski <m.szyprowski@samsung.com>
> Cc: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> ---
>  arch/arm/boot/dts/exynos4412.dtsi | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm/boot/dts/exynos4412.dtsi b/arch/arm/boot/dts/exynos4412.dtsi
> index ca0e3c1..294cfe4 100644
> --- a/arch/arm/boot/dts/exynos4412.dtsi
> +++ b/arch/arm/boot/dts/exynos4412.dtsi
> @@ -98,6 +98,7 @@
>  			opp-hz = /bits/ 64 <800000000>;
>  			opp-microvolt = <1000000>;
>  			clock-latency-ns = <200000>;
> +			opp-suspend;
>  		};
>  		opp07 {
>  			opp-hz = /bits/ 64 <900000000>;

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

-- 
viresh