Re: [RFC PATCH v5 05/10] thermal: let governors have private data for each thermal zone

["Javi Merino" <javi.merino@arm.com>]

On Tue, Aug 19, 2014 at 01:49:32PM +0100, edubezval@gmail.com wrote:
> Javi,

Hi Eduardo,

> On Thu, Jul 10, 2014 at 10:18 AM, Javi Merino <javi.merino@arm.com> wrote:
> > A governor may need to store its current state between calls to
> > throttle().  That state depends on the thermal zone, so store it as
> > private data in struct thermal_zone_device.
> >
> > The governors may have two new ops: bind_to_tz() and unbind_from_tz().
> > When provided, these functions let governors do some initialization
> > and teardown when they are bound/unbound to a tz and possibly store that
> > information in the governor_data field of the struct
> > thermal_zone_device.
> >
> > Cc: Zhang Rui <rui.zhang@intel.com>
> > Cc: Eduardo Valentin <edubezval@gmail.com>
> > Signed-off-by: Javi Merino <javi.merino@arm.com>
> > ---
> >  drivers/thermal/thermal_core.c | 83 ++++++++++++++++++++++++++++++++++++++----
> >  include/linux/thermal.h        |  9 +++++
> >  2 files changed, 84 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> > index 71b0ec0c370d..3da99dd80ad5 100644
> > --- a/drivers/thermal/thermal_core.c
> > +++ b/drivers/thermal/thermal_core.c
> > @@ -72,6 +72,58 @@ static struct thermal_governor *__find_governor(const char *name)
> >         return NULL;
> >  }
> >
> > +/**
> > + * bind_previous_governor() - bind the previous governor of the thermal zone
> > + * @tz:                a valid pointer to a struct thermal_zone_device
> > + * @failed_gov_name:   the name of the governor that failed to register
> > + *
> > + * Register the previous governor of the thermal zone after a new
> > + * governor has failed to be bound.
> > + */
> > +static void bind_previous_governor(struct thermal_zone_device *tz,
> > +                               const char *failed_gov_name)
> > +{
> > +       if (tz->governor && tz->governor->bind_to_tz) {
> > +               if (tz->governor->bind_to_tz(tz)) {
> > +                       dev_warn(&tz->device,
> > +                               "governor %s failed to bind and the previous one (%s) failed to register again, thermal zone %s has no governor\n",
> > +                               failed_gov_name, tz->governor->name, tz->type);
> 
> The above must be a dev_err(), not warn.

Sure

>                                          Besides, I would prefer if
> you could improve the message. What is the difference between register
> and bind?

None.  It should say bind in both, it'll make it clearer.  I'll fix
it.

> > +                       tz->governor = NULL;
> > +               }
> > +       }
> > +}
> > +
> > +/**
> > + * thermal_set_governor() - Switch to another governor
> > + * @tz:                a valid pointer to a struct thermal_zone_device
> > + * @new_gov:   pointer to the new governor
> > + *
> > + * Change the governor of thermal zone @tz.
> > + *
> > + * Return: 0 on success, an error if the new governor's bind_to_tz() failed.
> > + */
> > +static int thermal_set_governor(struct thermal_zone_device *tz,
> > +                               struct thermal_governor *new_gov)
> > +{
> > +       int ret = 0;
> > +
> > +       if (tz->governor && tz->governor->unbind_from_tz)
> > +               tz->governor->unbind_from_tz(tz);
> > +
> > +       if (new_gov && new_gov->bind_to_tz) {
> > +               ret = new_gov->bind_to_tz(tz);
> > +               if (ret) {
> > +                       bind_previous_governor(tz, new_gov->name);
> > +
> > +                       return ret;
> > +               }
> > +       }
> > +
> > +       tz->governor = new_gov;
> > +
> > +       return ret;
> > +}
> > +
> >  int thermal_register_governor(struct thermal_governor *governor)
> >  {
> >         int err;
> > @@ -104,8 +156,15 @@ int thermal_register_governor(struct thermal_governor *governor)
> >
> >                 name = pos->tzp->governor_name;
> >
> > -               if (!strnicmp(name, governor->name, THERMAL_NAME_LENGTH))
> > -                       pos->governor = governor;
> > +               if (!strnicmp(name, governor->name, THERMAL_NAME_LENGTH)) {
> > +                       int ret;
> > +
> > +                       ret = thermal_set_governor(pos, governor);
> > +                       if (ret)
> > +                               dev_warn(&pos->device,
> > +                                       "Failed to set governor %s for thermal zone %s: %d\n",
> > +                                       governor->name, pos->type, ret);
> 
> dev_err here too.

Ok.  Thanks!
Javi 

> > +               }
> >         }
> >
> >         mutex_unlock(&thermal_list_lock);
> > @@ -131,7 +190,7 @@ void thermal_unregister_governor(struct thermal_governor *governor)
> >         list_for_each_entry(pos, &thermal_tz_list, node) {
> >                 if (!strnicmp(pos->governor->name, governor->name,
> >                                                 THERMAL_NAME_LENGTH))
> > -                       pos->governor = NULL;
> > +                       thermal_set_governor(pos, NULL);
> >         }
> >
> >         mutex_unlock(&thermal_list_lock);
> > @@ -756,8 +815,9 @@ policy_store(struct device *dev, struct device_attribute *attr,
> >         if (!gov)
> >                 goto exit;
> >
> > -       tz->governor = gov;
> > -       ret = count;
> > +       ret = thermal_set_governor(tz, gov);
> > +       if (!ret)
> > +               ret = count;
> >
> >  exit:
> >         mutex_unlock(&thermal_governor_lock);
> > @@ -1452,6 +1512,7 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
> >         int result;
> >         int count;
> >         int passive = 0;
> > +       struct thermal_governor *governor;
> >
> >         if (type && strlen(type) >= THERMAL_NAME_LENGTH)
> >                 return ERR_PTR(-EINVAL);
> > @@ -1542,9 +1603,15 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
> >         mutex_lock(&thermal_governor_lock);
> >
> >         if (tz->tzp)
> > -               tz->governor = __find_governor(tz->tzp->governor_name);
> > +               governor = __find_governor(tz->tzp->governor_name);
> >         else
> > -               tz->governor = def_governor;
> > +               governor = def_governor;
> > +
> > +       result = thermal_set_governor(tz, governor);
> > +       if (result) {
> > +               mutex_unlock(&thermal_governor_lock);
> > +               goto unregister;
> > +       }
> >
> >         mutex_unlock(&thermal_governor_lock);
> >
> > @@ -1634,7 +1701,7 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
> >                 device_remove_file(&tz->device, &dev_attr_mode);
> >         device_remove_file(&tz->device, &dev_attr_policy);
> >         remove_trip_attrs(tz);
> > -       tz->governor = NULL;
> > +       thermal_set_governor(tz, NULL);
> >
> >         thermal_remove_hwmon_sysfs(tz);
> >         release_idr(&thermal_tz_idr, &thermal_idr_lock, tz->id);
> > diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> > index 0305cde21a74..1124b7a9358a 100644
> > --- a/include/linux/thermal.h
> > +++ b/include/linux/thermal.h
> > @@ -187,6 +187,7 @@ struct thermal_attr {
> >   * @ops:       operations this &thermal_zone_device supports
> >   * @tzp:       thermal zone parameters
> >   * @governor:  pointer to the governor for this thermal zone
> > + * @governor_data:     private pointer for governor data
> >   * @thermal_instances: list of &struct thermal_instance of this thermal zone
> >   * @idr:       &struct idr to generate unique id for this zone's cooling
> >   *             devices
> > @@ -213,6 +214,7 @@ struct thermal_zone_device {
> >         struct thermal_zone_device_ops *ops;
> >         const struct thermal_zone_params *tzp;
> >         struct thermal_governor *governor;
> > +       void *governor_data;
> >         struct list_head thermal_instances;
> >         struct idr idr;
> >         struct mutex lock;
> > @@ -223,12 +225,19 @@ struct thermal_zone_device {
> >  /**
> >   * struct thermal_governor - structure that holds thermal governor information
> >   * @name:      name of the governor
> > + * @bind_to_tz: callback called when binding to a thermal zone.  If it
> > + *             returns 0, the governor is bound to the thermal zone,
> > + *             otherwise it fails.
> > + * @unbind_from_tz:    callback called when a governor is unbound from a
> > + *                     thermal zone.
> >   * @throttle:  callback called for every trip point even if temperature is
> >   *             below the trip point temperature
> >   * @governor_list:     node in thermal_governor_list (in thermal_core.c)
> >   */
> >  struct thermal_governor {
> >         char name[THERMAL_NAME_LENGTH];
> > +       int (*bind_to_tz)(struct thermal_zone_device *tz);
> > +       void (*unbind_from_tz)(struct thermal_zone_device *tz);
> >         int (*throttle)(struct thermal_zone_device *tz, int trip);
> >         struct list_head        governor_list;
> >  };
> > --
> > 1.9.1
> >
> >
> 
> 
> 
> -- 
> Eduardo Bezerra Valentin
>