[PATCH] PM: OPP: introduce function to free cpufreq table

[PATCH] PM: OPP: introduce function to free cpufreq table

[Nishanth Menon]

cpufreq table allocated by opp_init_cpufreq_table is better
freed by OPP layer itself. This allows future modifications to
the table handling to be transparent to the users.

Signed-off-by: Nishanth Menon <nm@ti.com>
---

Example discussion: http://marc.info/?t=130570440600005&r=1&w=2

 Documentation/power/opp.txt |    2 ++
 drivers/base/power/opp.c    |   20 ++++++++++++++++++++
 include/linux/opp.h         |    8 ++++++++
 3 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/Documentation/power/opp.txt b/Documentation/power/opp.txt
index 5ae70a1..3035d00 100644
--- a/Documentation/power/opp.txt
+++ b/Documentation/power/opp.txt
@@ -321,6 +321,8 @@ opp_init_cpufreq_table - cpufreq framework typically is initialized with
 	addition to CONFIG_PM as power management feature is required to
 	dynamically scale voltage and frequency in a system.
 
+opp_free_cpufreq_table - Free up the table allocated by opp_init_cpufreq_table
+
 7. Data Structures
 ==================
 Typically an SoC contains multiple voltage domains which are variable. Each
diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index 56a6899..bf0c2ee 100644
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -625,4 +625,24 @@ int opp_init_cpufreq_table(struct device *dev,
 
 	return 0;
 }
+
+/**
+ * opp_free_cpufreq_table() - free the cpufreq table
+ * @dev:	device for which we do this operation
+ * @table:	table to free
+ *
+ * Free up the table allocated by opp_init_cpufreq_table
+ */
+void opp_free_cpufreq_table(struct device *dev,
+				struct cpufreq_frequency_table **table)
+{
+	if (!table)
+		return;
+
+	/* Pretend as if I am an updater */
+	mutex_lock(&dev_opp_list_lock);
+	kfree(*table);
+	*table = NULL;
+	mutex_unlock(&dev_opp_list_lock);
+}
 #endif		/* CONFIG_CPU_FREQ */
diff --git a/include/linux/opp.h b/include/linux/opp.h
index 5449945..7020e97 100644
--- a/include/linux/opp.h
+++ b/include/linux/opp.h
@@ -94,12 +94,20 @@ static inline int opp_disable(struct device *dev, unsigned long freq)
 #if defined(CONFIG_CPU_FREQ) && defined(CONFIG_PM_OPP)
 int opp_init_cpufreq_table(struct device *dev,
 			    struct cpufreq_frequency_table **table);
+void opp_free_cpufreq_table(struct device *dev,
+				struct cpufreq_frequency_table **table);
 #else
 static inline int opp_init_cpufreq_table(struct device *dev,
 			    struct cpufreq_frequency_table **table)
 {
 	return -EINVAL;
 }
+
+static inline
+void opp_free_cpufreq_table(struct device *dev,
+				struct cpufreq_frequency_table **table)
+{
+}
 #endif		/* CONFIG_CPU_FREQ */
 
 #endif		/* __LINUX_OPP_H__ */
-- 
1.7.1

Re: [PATCH] PM: OPP: introduce function to free cpufreq table

[Todd Poynor]

On Mon, May 23, 2011 at 06:12:15PM -0500, Nishanth Menon wrote:
> cpufreq table allocated by opp_init_cpufreq_table is better
> freed by OPP layer itself. This allows future modifications to
> the table handling to be transparent to the users.
...
> +void opp_free_cpufreq_table(struct device *dev,
> +				struct cpufreq_frequency_table **table)
> +{
> +	if (!table)
> +		return;
> +
> +	/* Pretend as if I am an updater */
> +	mutex_lock(&dev_opp_list_lock);
> +	kfree(*table);
> +	*table = NULL;
> +	mutex_unlock(&dev_opp_list_lock);
> +}

Not clear what the mutex protects here.  Currently it protects only
device opp list modifications.  opp_init_cpufreq_table holds the lock only
while looking up and walking the device opp list; the cpufreq table it
creates is not complete by the time the lock is dropped.


Todd

Re: [PATCH] PM: OPP: introduce function to free cpufreq table

[Todd Poynor]

On Mon, May 23, 2011 at 06:12:15PM -0500, Nishanth Menon wrote:
> cpufreq table allocated by opp_init_cpufreq_table is better
> freed by OPP layer itself. This allows future modifications to
> the table handling to be transparent to the users.
...
> +void opp_free_cpufreq_table(struct device *dev,
> +				struct cpufreq_frequency_table **table)
> +{
> +	if (!table)
> +		return;
> +
> +	/* Pretend as if I am an updater */
> +	mutex_lock(&dev_opp_list_lock);
> +	kfree(*table);
> +	*table = NULL;
> +	mutex_unlock(&dev_opp_list_lock);
> +}

Not clear what the mutex protects here.  Currently it protects only
device opp list modifications.  opp_init_cpufreq_table holds the lock only
while looking up and walking the device opp list; the cpufreq table it
creates is not complete by the time the lock is dropped.


Todd

Re: [PATCH] PM: OPP: introduce function to free cpufreq table

[Menon, Nishanth]

On Mon, May 23, 2011 at 19:05, Todd Poynor <toddpoynor@google.com> wrote:
> On Mon, May 23, 2011 at 06:12:15PM -0500, Nishanth Menon wrote:
>> cpufreq table allocated by opp_init_cpufreq_table is better
>> freed by OPP layer itself. This allows future modifications to
>> the table handling to be transparent to the users.
> ...
>> +void opp_free_cpufreq_table(struct device *dev,
>> +                             struct cpufreq_frequency_table **table)
>> +{
>> +     if (!table)
>> +             return;
>> +
>> +     /* Pretend as if I am an updater */
>> +     mutex_lock(&dev_opp_list_lock);
>> +     kfree(*table);
>> +     *table = NULL;
>> +     mutex_unlock(&dev_opp_list_lock);
>> +}
>
> Not clear what the mutex protects here.  Currently it protects only
> device opp list modifications.  opp_init_cpufreq_table holds the lock only
> while looking up and walking the device opp list; the cpufreq table it
> creates is not complete by the time the lock is dropped.

hmm.. right.. mutex protection does'nt really make sense here..

Regards,
Nishanth Menon

Re: [PATCH] PM: OPP: introduce function to free cpufreq table

[Menon, Nishanth]

On Mon, May 23, 2011 at 19:05, Todd Poynor <toddpoynor@google.com> wrote:
> On Mon, May 23, 2011 at 06:12:15PM -0500, Nishanth Menon wrote:
>> cpufreq table allocated by opp_init_cpufreq_table is better
>> freed by OPP layer itself. This allows future modifications to
>> the table handling to be transparent to the users.
> ...
>> +void opp_free_cpufreq_table(struct device *dev,
>> +                             struct cpufreq_frequency_table **table)
>> +{
>> +     if (!table)
>> +             return;
>> +
>> +     /* Pretend as if I am an updater */
>> +     mutex_lock(&dev_opp_list_lock);
>> +     kfree(*table);
>> +     *table = NULL;
>> +     mutex_unlock(&dev_opp_list_lock);
>> +}
>
> Not clear what the mutex protects here.  Currently it protects only
> device opp list modifications.  opp_init_cpufreq_table holds the lock only
> while looking up and walking the device opp list; the cpufreq table it
> creates is not complete by the time the lock is dropped.

hmm.. right.. mutex protection does'nt really make sense here..

Regards,
Nishanth Menon
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Re: [PATCH] PM: OPP: introduce function to free cpufreq table

[Rafael J. Wysocki]

On Tuesday, May 24, 2011, Menon, Nishanth wrote:
> On Mon, May 23, 2011 at 19:05, Todd Poynor <toddpoynor@google.com> wrote:
> > On Mon, May 23, 2011 at 06:12:15PM -0500, Nishanth Menon wrote:
> >> cpufreq table allocated by opp_init_cpufreq_table is better
> >> freed by OPP layer itself. This allows future modifications to
> >> the table handling to be transparent to the users.
> > ...
> >> +void opp_free_cpufreq_table(struct device *dev,
> >> +                             struct cpufreq_frequency_table **table)
> >> +{
> >> +     if (!table)
> >> +             return;
> >> +
> >> +     /* Pretend as if I am an updater */
> >> +     mutex_lock(&dev_opp_list_lock);
> >> +     kfree(*table);
> >> +     *table = NULL;
> >> +     mutex_unlock(&dev_opp_list_lock);
> >> +}
> >
> > Not clear what the mutex protects here.  Currently it protects only
> > device opp list modifications.  opp_init_cpufreq_table holds the lock only
> > while looking up and walking the device opp list; the cpufreq table it
> > creates is not complete by the time the lock is dropped.
> 
> hmm.. right.. mutex protection does'nt really make sense here..

Care to post an updated patch?

Rafael

Re: [PATCH] PM: OPP: introduce function to free cpufreq table

[Rafael J. Wysocki]

On Tuesday, May 24, 2011, Menon, Nishanth wrote:
> On Mon, May 23, 2011 at 19:05, Todd Poynor <toddpoynor@google.com> wrote:
> > On Mon, May 23, 2011 at 06:12:15PM -0500, Nishanth Menon wrote:
> >> cpufreq table allocated by opp_init_cpufreq_table is better
> >> freed by OPP layer itself. This allows future modifications to
> >> the table handling to be transparent to the users.
> > ...
> >> +void opp_free_cpufreq_table(struct device *dev,
> >> +                             struct cpufreq_frequency_table **table)
> >> +{
> >> +     if (!table)
> >> +             return;
> >> +
> >> +     /* Pretend as if I am an updater */
> >> +     mutex_lock(&dev_opp_list_lock);
> >> +     kfree(*table);
> >> +     *table = NULL;
> >> +     mutex_unlock(&dev_opp_list_lock);
> >> +}
> >
> > Not clear what the mutex protects here.  Currently it protects only
> > device opp list modifications.  opp_init_cpufreq_table holds the lock only
> > while looking up and walking the device opp list; the cpufreq table it
> > creates is not complete by the time the lock is dropped.
> 
> hmm.. right.. mutex protection does'nt really make sense here..

Care to post an updated patch?

Rafael

[PATCH] PM: OPP: introduce function to free cpufreq table

[Nishanth Menon]

cpufreq table allocated by opp_init_cpufreq_table is better
freed by OPP layer itself. This allows future modifications to
the table handling to be transparent to the users.

Signed-off-by: Nishanth Menon <nm@ti.com>
---

Example discussion: http://marc.info/?t=130570440600005&r=1&w=2

 Documentation/power/opp.txt |    2 ++
 drivers/base/power/opp.c    |   20 ++++++++++++++++++++
 include/linux/opp.h         |    8 ++++++++
 3 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/Documentation/power/opp.txt b/Documentation/power/opp.txt
index 5ae70a1..3035d00 100644
--- a/Documentation/power/opp.txt
+++ b/Documentation/power/opp.txt
@@ -321,6 +321,8 @@ opp_init_cpufreq_table - cpufreq framework typically is initialized with
 	addition to CONFIG_PM as power management feature is required to
 	dynamically scale voltage and frequency in a system.
 
+opp_free_cpufreq_table - Free up the table allocated by opp_init_cpufreq_table
+
 7. Data Structures
 ==================
 Typically an SoC contains multiple voltage domains which are variable. Each
diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index 56a6899..bf0c2ee 100644
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -625,4 +625,24 @@ int opp_init_cpufreq_table(struct device *dev,
 
 	return 0;
 }
+
+/**
+ * opp_free_cpufreq_table() - free the cpufreq table
+ * @dev:	device for which we do this operation
+ * @table:	table to free
+ *
+ * Free up the table allocated by opp_init_cpufreq_table
+ */
+void opp_free_cpufreq_table(struct device *dev,
+				struct cpufreq_frequency_table **table)
+{
+	if (!table)
+		return;
+
+	/* Pretend as if I am an updater */
+	mutex_lock(&dev_opp_list_lock);
+	kfree(*table);
+	*table = NULL;
+	mutex_unlock(&dev_opp_list_lock);
+}
 #endif		/* CONFIG_CPU_FREQ */
diff --git a/include/linux/opp.h b/include/linux/opp.h
index 5449945..7020e97 100644
--- a/include/linux/opp.h
+++ b/include/linux/opp.h
@@ -94,12 +94,20 @@ static inline int opp_disable(struct device *dev, unsigned long freq)
 #if defined(CONFIG_CPU_FREQ) && defined(CONFIG_PM_OPP)
 int opp_init_cpufreq_table(struct device *dev,
 			    struct cpufreq_frequency_table **table);
+void opp_free_cpufreq_table(struct device *dev,
+				struct cpufreq_frequency_table **table);
 #else
 static inline int opp_init_cpufreq_table(struct device *dev,
 			    struct cpufreq_frequency_table **table)
 {
 	return -EINVAL;
 }
+
+static inline
+void opp_free_cpufreq_table(struct device *dev,
+				struct cpufreq_frequency_table **table)
+{
+}
 #endif		/* CONFIG_CPU_FREQ */
 
 #endif		/* __LINUX_OPP_H__ */
-- 
1.7.1