Hello Rui,
On Mon, Jun 11, 2012 at 11:20:39AM +0800, Zhang Rui wrote:
>
> Introduce simple arbitrator for setting device cooling state,
> to fix the problem that a cooling device may be referenced by
> by multiple trip points in multiple thermal zones.
>
>
> With this patch, we have two stages for updating a thermal zone,
> 1. check if a thermal_instance needs to be updated or not
> 2. update the cooling device, based on the target cooling state
> of all its instances.
>
> Note that, currently, the cooling device is set to the deepest
> cooling state required.
>
> Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
> ---
> drivers/thermal/thermal_sys.c | 41 ++++++++++++++++++++++++++++++++++++++---
> include/linux/thermal.h | 1 +
> 2 files changed, 39 insertions(+), 3 deletions(-)
>
> Index: rtd3/drivers/thermal/thermal_sys.c
> ===================================================================
> --- rtd3.orig/drivers/thermal/thermal_sys.c
> +++ rtd3/drivers/thermal/thermal_sys.c
> @@ -54,6 +54,7 @@ struct thermal_instance {
> int trip;
> unsigned long upper; /* Highest cooling state for this trip point */
> unsigned long lower; /* Lowest cooling state for this trip point */
> + unsigned long target; /* expected cooling state */
> char attr_name[THERMAL_NAME_LENGTH];
> struct device_attribute attr;
> struct list_head tz_node; /* node in tz->instances */
> @@ -812,6 +813,7 @@ int thermal_zone_bind_cooling_device(str
> dev->trip = trip;
> dev->upper = upper;
> dev->lower = lower;
> + dev->target = -1;
>
> result = get_idr(&tz->idr, &tz->lock, &dev->id);
> if (result)
> @@ -949,6 +951,7 @@ thermal_cooling_device_register(char *ty
> strcpy(cdev->type, type);
> INIT_LIST_HEAD(&cdev->instances);
> cdev->ops = ops;
> + cdev->updated = 1;
> cdev->device.class = &thermal_class;
> cdev->devdata = devdata;
> dev_set_name(&cdev->device, "cooling_device%d", cdev->id);
> @@ -1040,6 +1043,32 @@ void thermal_cooling_device_unregister(s
> }
> EXPORT_SYMBOL(thermal_cooling_device_unregister);
>
> +static void thermal_zone_do_update(struct thermal_zone_device *tz)
> +{
> + struct thermal_instance *instance1, *instance2;
> + struct thermal_cooling_device *cdev;
> + int target;
> +
> + list_for_each_entry(instance1, &tz->instances, tz_node) {
> + cdev = instance1->cdev;
> +
> + /* cooling device has already been updated*/
> + if (cdev->updated)
> + continue;
> +
> + target = 0;
> + /* Make sure cdev enters the deepest cooling state */
> + list_for_each_entry(instance2, &cdev->instances, cdev_node) {
> + if (instance2->target == -1)
> + continue;
> + if (instance2->target > target)
> + target = instance2->target;
> + }
> + cdev->ops->set_cur_state(cdev, target);
> + cdev->updated = 1;
> + }
> +}
I think the above arbitrator solution does not escalate. As I can see,
the arbitrator takes care of cooling device instances in the same thermal zone.
What if you have a device which expose cooling device instances in different
thermal zones?
Besides, the thermal constraint might collide with pm QoS or with settings
coming from user space interfaces.
That's actually why I was suggesting to have this 'arbitrator' or constraint
management outside the thermal framework. And managed per device at some
other abstraction layer.
> +
> /*
> * Cooling algorithm for active trip points
> *
> @@ -1086,19 +1115,24 @@ static void thermal_zone_trip_update(str
> cur_state = cur_state > instance->lower ?
> (cur_state - 1) : instance->lower;
> }
> - cdev->ops->set_cur_state(cdev, cur_state);
> + instance->target = cur_state;
> + cdev->updated = 0; /* cooling device needs update */
> }
> } else { /* below trip */
> list_for_each_entry(instance, &tz->instances, tz_node) {
> if (instance->trip != trip)
> continue;
>
> + /* Do not use the deacitve thermal instance */
> + if (instance->target == -1)
> + continue;
> cdev = instance->cdev;
> cdev->ops->get_cur_state(cdev, &cur_state);
>
> cur_state = cur_state > instance->lower ?
> - (cur_state - 1) : instance->lower;
> - cdev->ops->set_cur_state(cdev, cur_state);
> + (cur_state - 1) : -1;
> + instance->target = cur_state;
> + cdev->updated = 0; /* cooling device needs update */
> }
> }
>
> @@ -1159,6 +1193,7 @@ void thermal_zone_device_update(struct t
> }
> }
>
> + thermal_zone_do_update(tz);
> if (tz->forced_passive)
> thermal_zone_device_passive(tz, temp, tz->forced_passive,
> THERMAL_TRIPS_NONE);
> Index: rtd3/include/linux/thermal.h
> ===================================================================
> --- rtd3.orig/include/linux/thermal.h
> +++ rtd3/include/linux/thermal.h
> @@ -86,6 +86,7 @@ struct thermal_cooling_device {
> struct device device;
> void *devdata;
> const struct thermal_cooling_device_ops *ops;
> + int updated; /* 1 if the cooling device does not need update */
> struct list_head instances;
> struct list_head node;
> };
>
>
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