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Date: Tue, 19 Aug 2014 08:49:32 -0400
From: "edubezval@...il.com" <edubezval@...il.com>
To: Javi Merino <javi.merino@....com>
Cc: "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>,
Punit Agrawal <punit.agrawal@....com>, broonie@...nel.org,
Zhang Rui <rui.zhang@...el.com>
Subject: Re: [RFC PATCH v5 05/10] thermal: let governors have private data for
each thermal zone
Javi,
On Thu, Jul 10, 2014 at 10:18 AM, Javi Merino <javi.merino@....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@...el.com>
> Cc: Eduardo Valentin <edubezval@...il.com>
> Signed-off-by: Javi Merino <javi.merino@....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. Besides, I would prefer if
you could improve the message. What is the difference between register
and bind?
> + 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.
> + }
> }
>
> 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
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