[PATCH] opp: Return genpd virtual devices from dev_pm_opp_attach_genpd()

[PATCH] opp: Return genpd virtual devices from dev_pm_opp_attach_genpd()

[Viresh Kumar]

The cpufreq drivers don't need to do runtime PM operations on the
virtual devices returned by dev_pm_domain_attach_by_name() and so the
virtual devices weren't shared with the callers of
dev_pm_opp_attach_genpd() earlier.

But the IO device drivers would want to do that. This patch updates the
prototype of dev_pm_opp_attach_genpd() to accept another argument to
return the pointer to the array of genpd virtual devices.

Reported-by: Rajendra Nayak <rnayak@codeaurora.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
@Rajendra: Can you please test this one ? I have only compile tested it.

 drivers/opp/core.c     | 5 ++++-
 include/linux/pm_opp.h | 4 ++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 2958cc7bbb58..07b6f1187b3b 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1775,6 +1775,7 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
  * dev_pm_opp_attach_genpd - Attach genpd(s) for the device and save virtual device pointer
  * @dev: Consumer device for which the genpd is getting attached.
  * @names: Null terminated array of pointers containing names of genpd to attach.
+ * @virt_devs: Pointer to return the array of virtual devices.
  *
  * Multiple generic power domains for a device are supported with the help of
  * virtual genpd devices, which are created for each consumer device - genpd
@@ -1789,7 +1790,8 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
  * This helper needs to be called once with a list of all genpd to attach.
  * Otherwise the original device structure will be used instead by the OPP core.
  */
-struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names)
+struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
+		const char **names, struct device ***virt_devs)
 {
 	struct opp_table *opp_table;
 	struct device *virt_dev;
@@ -1850,6 +1852,7 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names
 		name++;
 	}
 
+	*virt_devs = opp_table->genpd_virt_devs;
 	mutex_unlock(&opp_table->genpd_virt_dev_lock);
 
 	return opp_table;
diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index be570761b77a..7c2fe2952f40 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -131,7 +131,7 @@ struct opp_table *dev_pm_opp_set_clkname(struct device *dev, const char * name);
 void dev_pm_opp_put_clkname(struct opp_table *opp_table);
 struct opp_table *dev_pm_opp_register_set_opp_helper(struct device *dev, int (*set_opp)(struct dev_pm_set_opp_data *data));
 void dev_pm_opp_unregister_set_opp_helper(struct opp_table *opp_table);
-struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names);
+struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names, struct device ***virt_devs);
 void dev_pm_opp_detach_genpd(struct opp_table *opp_table);
 int dev_pm_opp_xlate_performance_state(struct opp_table *src_table, struct opp_table *dst_table, unsigned int pstate);
 int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq);
@@ -295,7 +295,7 @@ static inline struct opp_table *dev_pm_opp_set_clkname(struct device *dev, const
 
 static inline void dev_pm_opp_put_clkname(struct opp_table *opp_table) {}
 
-static inline struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names)
+static inline struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names, struct device ***virt_devs)
 {
 	return ERR_PTR(-ENOTSUPP);
 }
-- 
2.21.0.rc0.269.g1a574e7a288b

Re: [PATCH] opp: Return genpd virtual devices from dev_pm_opp_attach_genpd()

[Rajendra Nayak]

On 7/8/2019 11:30 AM, Viresh Kumar wrote:
> The cpufreq drivers don't need to do runtime PM operations on the
> virtual devices returned by dev_pm_domain_attach_by_name() and so the
> virtual devices weren't shared with the callers of
> dev_pm_opp_attach_genpd() earlier.
> 
> But the IO device drivers would want to do that. This patch updates the
> prototype of dev_pm_opp_attach_genpd() to accept another argument to
> return the pointer to the array of genpd virtual devices.
> 
> Reported-by: Rajendra Nayak <rnayak@codeaurora.org>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> @Rajendra: Can you please test this one ? I have only compile tested it.

Sorry for the delay, I seem to have completely missed this patch.
I just gave this a try and here are some observations,

I have a case where I have one device with 2 power domains, one of them
is scale-able (supports perf state) and the other one supports only being
turned on and off.

1. In the driver I now need to use dev_pm_domain_attach_by_name/id to attach the
power domain which supports only on/off and then use dev_pm_opp_attach_genpd()
for the one which supports perf states.

2. My OPP table has only 1 required_opps, so the required_opp_count for the OPP table is 1.
Now if my device tree has my scale-able powerdomain at index 1 (it works if its at index 0)
then I end up with this error

[    2.858628] ufshcd-qcom 1d84000.ufshc: Index can't be greater than required-opp-count - 1, rpmh_pd (1 : 1)

so it looks like a lot of the OPP core today just assumes that if a device has multiple power domains,
all of them are scale-able which isn't necessarily true.

> 
>   drivers/opp/core.c     | 5 ++++-
>   include/linux/pm_opp.h | 4 ++--
>   2 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 2958cc7bbb58..07b6f1187b3b 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -1775,6 +1775,7 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
>    * dev_pm_opp_attach_genpd - Attach genpd(s) for the device and save virtual device pointer
>    * @dev: Consumer device for which the genpd is getting attached.
>    * @names: Null terminated array of pointers containing names of genpd to attach.
> + * @virt_devs: Pointer to return the array of virtual devices.
>    *
>    * Multiple generic power domains for a device are supported with the help of
>    * virtual genpd devices, which are created for each consumer device - genpd
> @@ -1789,7 +1790,8 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
>    * This helper needs to be called once with a list of all genpd to attach.
>    * Otherwise the original device structure will be used instead by the OPP core.
>    */
> -struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names)
> +struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
> +		const char **names, struct device ***virt_devs)
>   {
>   	struct opp_table *opp_table;
>   	struct device *virt_dev;
> @@ -1850,6 +1852,7 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names
>   		name++;
>   	}
>   
> +	*virt_devs = opp_table->genpd_virt_devs;
>   	mutex_unlock(&opp_table->genpd_virt_dev_lock);
>   
>   	return opp_table;
> diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
> index be570761b77a..7c2fe2952f40 100644
> --- a/include/linux/pm_opp.h
> +++ b/include/linux/pm_opp.h
> @@ -131,7 +131,7 @@ struct opp_table *dev_pm_opp_set_clkname(struct device *dev, const char * name);
>   void dev_pm_opp_put_clkname(struct opp_table *opp_table);
>   struct opp_table *dev_pm_opp_register_set_opp_helper(struct device *dev, int (*set_opp)(struct dev_pm_set_opp_data *data));
>   void dev_pm_opp_unregister_set_opp_helper(struct opp_table *opp_table);
> -struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names);
> +struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names, struct device ***virt_devs);
>   void dev_pm_opp_detach_genpd(struct opp_table *opp_table);
>   int dev_pm_opp_xlate_performance_state(struct opp_table *src_table, struct opp_table *dst_table, unsigned int pstate);
>   int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq);
> @@ -295,7 +295,7 @@ static inline struct opp_table *dev_pm_opp_set_clkname(struct device *dev, const
>   
>   static inline void dev_pm_opp_put_clkname(struct opp_table *opp_table) {}
>   
> -static inline struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names)
> +static inline struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names, struct device ***virt_devs)
>   {
>   	return ERR_PTR(-ENOTSUPP);
>   }
> 

-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation

Re: [PATCH] opp: Return genpd virtual devices from dev_pm_opp_attach_genpd()

[Viresh Kumar]

On 11-07-19, 15:09, Rajendra Nayak wrote:
> Sorry for the delay

Same here :)

> I seem to have completely missed this patch.
> I just gave this a try and here are some observations,
> 
> I have a case where I have one device with 2 power domains, one of them
> is scale-able (supports perf state) and the other one supports only being
> turned on and off.
> 
> 1. In the driver I now need to use dev_pm_domain_attach_by_name/id to attach the
> power domain which supports only on/off and then use dev_pm_opp_attach_genpd()
> for the one which supports perf states.
> 
> 2. My OPP table has only 1 required_opps, so the required_opp_count for the OPP table is 1.
> Now if my device tree has my scale-able powerdomain at index 1 (it works if its at index 0)
> then I end up with this error
> 
> [    2.858628] ufshcd-qcom 1d84000.ufshc: Index can't be greater than required-opp-count - 1, rpmh_pd (1 : 1)
> 
> so it looks like a lot of the OPP core today just assumes that if a device has multiple power domains,
> all of them are scale-able which isn't necessarily true.

I don't think a lot of OPP core has these problems, but maybe only
this place. I was taking care of this since the beginning just forgot
it now.

What about this over this commit:

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index d76ead4eff4c..1f11f8c92337 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1789,13 +1789,16 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
  *
  * This helper needs to be called once with a list of all genpd to attach.
  * Otherwise the original device structure will be used instead by the OPP core.
+ *
+ * The order of entries in the names array must match the order in which
+ * "required-opps" are added in DT.
  */
 struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
                const char **names, struct device ***virt_devs)
 {
        struct opp_table *opp_table;
        struct device *virt_dev;
-       int index, ret = -EINVAL;
+       int index = 0, ret = -EINVAL;
        const char **name = names;
 
        opp_table = dev_pm_opp_get_opp_table(dev);
@@ -1821,14 +1824,6 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
                goto unlock;
 
        while (*name) {
-               index = of_property_match_string(dev->of_node,
-                                                "power-domain-names", *name);
-               if (index < 0) {
-                       dev_err(dev, "Failed to find power domain: %s (%d)\n",
-                               *name, index);
-                       goto err;
-               }
-
                if (index >= opp_table->required_opp_count) {
                        dev_err(dev, "Index can't be greater than required-opp-count - 1, %s (%d : %d)\n",
                                *name, opp_table->required_opp_count, index);
@@ -1849,6 +1844,7 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
                }
 
                opp_table->genpd_virt_devs[index] = virt_dev;
+               index++;
                name++;
        }
 

-- 
viresh

Re: [PATCH] opp: Return genpd virtual devices from dev_pm_opp_attach_genpd()

[Rajendra Nayak]

On 7/17/2019 11:17 AM, Viresh Kumar wrote:
> On 11-07-19, 15:09, Rajendra Nayak wrote:
>> Sorry for the delay
> 
> Same here :)
> 
>> I seem to have completely missed this patch.
>> I just gave this a try and here are some observations,
>>
>> I have a case where I have one device with 2 power domains, one of them
>> is scale-able (supports perf state) and the other one supports only being
>> turned on and off.
>>
>> 1. In the driver I now need to use dev_pm_domain_attach_by_name/id to attach the
>> power domain which supports only on/off and then use dev_pm_opp_attach_genpd()
>> for the one which supports perf states.
>>
>> 2. My OPP table has only 1 required_opps, so the required_opp_count for the OPP table is 1.
>> Now if my device tree has my scale-able powerdomain at index 1 (it works if its at index 0)
>> then I end up with this error
>>
>> [    2.858628] ufshcd-qcom 1d84000.ufshc: Index can't be greater than required-opp-count - 1, rpmh_pd (1 : 1)
>>
>> so it looks like a lot of the OPP core today just assumes that if a device has multiple power domains,
>> all of them are scale-able which isn't necessarily true.
> 
> I don't think a lot of OPP core has these problems, but maybe only
> this place. I was taking care of this since the beginning just forgot
> it now.
> 
> What about this over this commit:

Yes, this does seem to fix my concern mentioned in 2. above.

> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index d76ead4eff4c..1f11f8c92337 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -1789,13 +1789,16 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
>    *
>    * This helper needs to be called once with a list of all genpd to attach.
>    * Otherwise the original device structure will be used instead by the OPP core.
> + *
> + * The order of entries in the names array must match the order in which
> + * "required-opps" are added in DT.
>    */
>   struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
>                  const char **names, struct device ***virt_devs)
>   {
>          struct opp_table *opp_table;
>          struct device *virt_dev;
> -       int index, ret = -EINVAL;
> +       int index = 0, ret = -EINVAL;
>          const char **name = names;
>   
>          opp_table = dev_pm_opp_get_opp_table(dev);
> @@ -1821,14 +1824,6 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
>                  goto unlock;
>   
>          while (*name) {
> -               index = of_property_match_string(dev->of_node,
> -                                                "power-domain-names", *name);
> -               if (index < 0) {
> -                       dev_err(dev, "Failed to find power domain: %s (%d)\n",
> -                               *name, index);
> -                       goto err;
> -               }
> -
>                  if (index >= opp_table->required_opp_count) {
>                          dev_err(dev, "Index can't be greater than required-opp-count - 1, %s (%d : %d)\n",
>                                  *name, opp_table->required_opp_count, index);
> @@ -1849,6 +1844,7 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
>                  }
>   
>                  opp_table->genpd_virt_devs[index] = virt_dev;
> +               index++;
>                  name++;
>          }
>   
> 

-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation

Re: [PATCH] opp: Return genpd virtual devices from dev_pm_opp_attach_genpd()

[Viresh Kumar]

On 17-07-19, 15:34, Rajendra Nayak wrote:
> 
> 
> On 7/17/2019 11:17 AM, Viresh Kumar wrote:
> > On 11-07-19, 15:09, Rajendra Nayak wrote:
> > > Sorry for the delay
> > 
> > Same here :)
> > 
> > > I seem to have completely missed this patch.
> > > I just gave this a try and here are some observations,
> > > 
> > > I have a case where I have one device with 2 power domains, one of them
> > > is scale-able (supports perf state) and the other one supports only being
> > > turned on and off.
> > > 
> > > 1. In the driver I now need to use dev_pm_domain_attach_by_name/id to attach the
> > > power domain which supports only on/off and then use dev_pm_opp_attach_genpd()
> > > for the one which supports perf states.
> > > 
> > > 2. My OPP table has only 1 required_opps, so the required_opp_count for the OPP table is 1.
> > > Now if my device tree has my scale-able powerdomain at index 1 (it works if its at index 0)
> > > then I end up with this error
> > > 
> > > [    2.858628] ufshcd-qcom 1d84000.ufshc: Index can't be greater than required-opp-count - 1, rpmh_pd (1 : 1)
> > > 
> > > so it looks like a lot of the OPP core today just assumes that if a device has multiple power domains,
> > > all of them are scale-able which isn't necessarily true.
> > 
> > I don't think a lot of OPP core has these problems, but maybe only
> > this place. I was taking care of this since the beginning just forgot
> > it now.
> > 
> > What about this over this commit:
> 
> Yes, this does seem to fix my concern mentioned in 2. above.

Great. I will include your Tested-by:, Lemme know if you have any
objections.

-- 
viresh

Re: [PATCH] opp: Return genpd virtual devices from dev_pm_opp_attach_genpd()

[Niklas Cassel]

On Mon, Jul 08, 2019 at 11:30:11AM +0530, Viresh Kumar wrote:
> The cpufreq drivers don't need to do runtime PM operations on the
> virtual devices returned by dev_pm_domain_attach_by_name() and so the
> virtual devices weren't shared with the callers of
> dev_pm_opp_attach_genpd() earlier.
> 
> But the IO device drivers would want to do that. This patch updates the
> prototype of dev_pm_opp_attach_genpd() to accept another argument to
> return the pointer to the array of genpd virtual devices.
> 
> Reported-by: Rajendra Nayak <rnayak@codeaurora.org>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> @Rajendra: Can you please test this one ? I have only compile tested it.
> 
>  drivers/opp/core.c     | 5 ++++-
>  include/linux/pm_opp.h | 4 ++--
>  2 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 2958cc7bbb58..07b6f1187b3b 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -1775,6 +1775,7 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
>   * dev_pm_opp_attach_genpd - Attach genpd(s) for the device and save virtual device pointer
>   * @dev: Consumer device for which the genpd is getting attached.
>   * @names: Null terminated array of pointers containing names of genpd to attach.
> + * @virt_devs: Pointer to return the array of virtual devices.
>   *
>   * Multiple generic power domains for a device are supported with the help of
>   * virtual genpd devices, which are created for each consumer device - genpd
> @@ -1789,7 +1790,8 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
>   * This helper needs to be called once with a list of all genpd to attach.
>   * Otherwise the original device structure will be used instead by the OPP core.
>   */
> -struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names)
> +struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
> +		const char **names, struct device ***virt_devs)
>  {
>  	struct opp_table *opp_table;
>  	struct device *virt_dev;
> @@ -1850,6 +1852,7 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names
>  		name++;
>  	}
>  
> +	*virt_devs = opp_table->genpd_virt_devs;

Could we perhaps only do this if (virt_devs), that way callers can send in
NULL if they don't care about the genpd virtual devices.

Kind regards,
Niklas

>  	mutex_unlock(&opp_table->genpd_virt_dev_lock);
>  
>  	return opp_table;
> diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
> index be570761b77a..7c2fe2952f40 100644
> --- a/include/linux/pm_opp.h
> +++ b/include/linux/pm_opp.h
> @@ -131,7 +131,7 @@ struct opp_table *dev_pm_opp_set_clkname(struct device *dev, const char * name);
>  void dev_pm_opp_put_clkname(struct opp_table *opp_table);
>  struct opp_table *dev_pm_opp_register_set_opp_helper(struct device *dev, int (*set_opp)(struct dev_pm_set_opp_data *data));
>  void dev_pm_opp_unregister_set_opp_helper(struct opp_table *opp_table);
> -struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names);
> +struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names, struct device ***virt_devs);
>  void dev_pm_opp_detach_genpd(struct opp_table *opp_table);
>  int dev_pm_opp_xlate_performance_state(struct opp_table *src_table, struct opp_table *dst_table, unsigned int pstate);
>  int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq);
> @@ -295,7 +295,7 @@ static inline struct opp_table *dev_pm_opp_set_clkname(struct device *dev, const
>  
>  static inline void dev_pm_opp_put_clkname(struct opp_table *opp_table) {}
>  
> -static inline struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names)
> +static inline struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names, struct device ***virt_devs)
>  {
>  	return ERR_PTR(-ENOTSUPP);
>  }
> -- 
> 2.21.0.rc0.269.g1a574e7a288b
> 

Re: [PATCH] opp: Return genpd virtual devices from dev_pm_opp_attach_genpd()

[Viresh Kumar]

On 16-07-19, 12:43, Niklas Cassel wrote:
> On Mon, Jul 08, 2019 at 11:30:11AM +0530, Viresh Kumar wrote:
> > The cpufreq drivers don't need to do runtime PM operations on the
> > virtual devices returned by dev_pm_domain_attach_by_name() and so the
> > virtual devices weren't shared with the callers of
> > dev_pm_opp_attach_genpd() earlier.
> > 
> > But the IO device drivers would want to do that. This patch updates the
> > prototype of dev_pm_opp_attach_genpd() to accept another argument to
> > return the pointer to the array of genpd virtual devices.
> > 
> > Reported-by: Rajendra Nayak <rnayak@codeaurora.org>
> > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> > ---
> > @Rajendra: Can you please test this one ? I have only compile tested it.
> > 
> >  drivers/opp/core.c     | 5 ++++-
> >  include/linux/pm_opp.h | 4 ++--
> >  2 files changed, 6 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> > index 2958cc7bbb58..07b6f1187b3b 100644
> > --- a/drivers/opp/core.c
> > +++ b/drivers/opp/core.c
> > @@ -1775,6 +1775,7 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
> >   * dev_pm_opp_attach_genpd - Attach genpd(s) for the device and save virtual device pointer
> >   * @dev: Consumer device for which the genpd is getting attached.
> >   * @names: Null terminated array of pointers containing names of genpd to attach.
> > + * @virt_devs: Pointer to return the array of virtual devices.
> >   *
> >   * Multiple generic power domains for a device are supported with the help of
> >   * virtual genpd devices, which are created for each consumer device - genpd
> > @@ -1789,7 +1790,8 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
> >   * This helper needs to be called once with a list of all genpd to attach.
> >   * Otherwise the original device structure will be used instead by the OPP core.
> >   */
> > -struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names)
> > +struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
> > +		const char **names, struct device ***virt_devs)
> >  {
> >  	struct opp_table *opp_table;
> >  	struct device *virt_dev;
> > @@ -1850,6 +1852,7 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev, const char **names
> >  		name++;
> >  	}
> >  
> > +	*virt_devs = opp_table->genpd_virt_devs;
> 
> Could we perhaps only do this if (virt_devs), that way callers can send in
> NULL if they don't care about the genpd virtual devices.

That was the idea and I failed to add it :(

-- 
viresh