Re: [PATCH v6-resubmit of 1/4] PM / OPP: Add OPP availability change notifier.

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On Thu, Aug 18, 2011 at 6:51 PM, MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx> wrote:
> The patch enables to register notifier_block for an OPP-device in order
> to get notified for any changes in the availability of OPPs of the
> device. For example, if a new OPP is inserted or enable/disable status
> of an OPP is changed, the notifier is executed.
>
> This enables the usage of opp_add, opp_enable, and opp_disable to
> directly take effect with any connected entities such as CPUFREQ or
> DEVFREQ.
>
> Signed-off-by: MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx>
> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>

Reviewed-by: Mike Turquette <mturquette@xxxxxx>

Looks good to me.

Mike

> ---
> Changes
> - This patch (1/4 of the set) is resubmitted for the code style revise.
> - Added at devfreq patch set v6 replacing devfreq_update calls at OPP.
> ---
>  drivers/base/power/opp.c |   29 +++++++++++++++++++++++++++++
>  include/linux/opp.h      |   12 ++++++++++++
>  2 files changed, 41 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
> index b23de18..e6b4c89 100644
> --- a/drivers/base/power/opp.c
> +++ b/drivers/base/power/opp.c
> @@ -73,6 +73,7 @@ struct opp {
>  *             RCU usage: nodes are not modified in the list of device_opp,
>  *             however addition is possible and is secured by dev_opp_list_lock
>  * @dev:       device pointer
> + * @head:      notifier head to notify the OPP availability changes.
>  * @opp_list:  list of opps
>  *
>  * This is an internal data structure maintaining the link to opps attached to
> @@ -83,6 +84,7 @@ struct device_opp {
>        struct list_head node;
>
>        struct device *dev;
> +       struct srcu_notifier_head head;
>        struct list_head opp_list;
>  };
>
> @@ -404,6 +406,7 @@ int opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
>                }
>
>                dev_opp->dev = dev;
> +               srcu_init_notifier_head(&dev_opp->head);
>                INIT_LIST_HEAD(&dev_opp->opp_list);
>
>                /* Secure the device list modification */
> @@ -428,6 +431,11 @@ int opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
>        list_add_rcu(&new_opp->node, head);
>        mutex_unlock(&dev_opp_list_lock);
>
> +       /*
> +        * Notify the changes in the availability of the operable
> +        * frequency/voltage list.
> +        */
> +       srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_ADD, new_opp);
>        return 0;
>  }
>
> @@ -504,6 +512,14 @@ static int opp_set_availability(struct device *dev, unsigned long freq,
>        mutex_unlock(&dev_opp_list_lock);
>        synchronize_rcu();
>
> +       /* Notify the change of the OPP availability */
> +       if (availability_req)
> +               srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_ENABLE,
> +                                        new_opp);
> +       else
> +               srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_DISABLE,
> +                                        new_opp);
> +
>        /* clean up old opp */
>        new_opp = opp;
>        goto out;
> @@ -643,3 +659,16 @@ void opp_free_cpufreq_table(struct device *dev,
>        *table = NULL;
>  }
>  #endif         /* CONFIG_CPU_FREQ */
> +
> +/** opp_get_notifier() - find notifier_head of the device with opp
> + * @dev:       device pointer used to lookup device OPPs.
> + */
> +struct srcu_notifier_head *opp_get_notifier(struct device *dev)
> +{
> +       struct device_opp *dev_opp = find_device_opp(dev);
> +
> +       if (IS_ERR(dev_opp))
> +               return ERR_PTR(PTR_ERR(dev_opp)); /* matching type */
> +
> +       return &dev_opp->head;
> +}
> diff --git a/include/linux/opp.h b/include/linux/opp.h
> index 7020e97..87a9208 100644
> --- a/include/linux/opp.h
> +++ b/include/linux/opp.h
> @@ -16,9 +16,14 @@
>
>  #include <linux/err.h>
>  #include <linux/cpufreq.h>
> +#include <linux/notifier.h>
>
>  struct opp;
>
> +enum opp_event {
> +       OPP_EVENT_ADD, OPP_EVENT_ENABLE, OPP_EVENT_DISABLE,
> +};
> +
>  #if defined(CONFIG_PM_OPP)
>
>  unsigned long opp_get_voltage(struct opp *opp);
> @@ -40,6 +45,8 @@ int opp_enable(struct device *dev, unsigned long freq);
>
>  int opp_disable(struct device *dev, unsigned long freq);
>
> +struct srcu_notifier_head *opp_get_notifier(struct device *dev);
> +
>  #else
>  static inline unsigned long opp_get_voltage(struct opp *opp)
>  {
> @@ -89,6 +96,11 @@ static inline int opp_disable(struct device *dev, unsigned long freq)
>  {
>        return 0;
>  }
> +
> +struct srcu_notifier_head *opp_get_notifier(struct device *dev)
> +{
> +       return ERR_PTR(-EINVAL);
> +}
>  #endif         /* CONFIG_PM */
>
>  #if defined(CONFIG_CPU_FREQ) && defined(CONFIG_PM_OPP)
> --
> 1.7.4.1
>
>
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