Re: [PATCH v4 resend] PM / QoS: add pm_qos_update_request_timeout API

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Wednesday, March 28, 2012, MyungJoo Ham wrote:
> The new API, pm_qos_update_request_timeout() is to provide a timeout
> with pm_qos_update_request.
> 
> For example, pm_qos_update_request_timeout(req, 100, 1000), means that
> QoS request on req with value 100 will be active for 1000 microseconds.
> After 1000 microseconds, the QoS request thru req is reset. If there
> were another pm_qos_update_request(req, x) during the 1000 us, this
> new request with value x will override as this is another request on the
> same req handle. A new request on the same req handle will always
> override the previous request whether it is the conventional request or
> it is the new timeout request.
> 
> Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> Acked-by: Mark Gross <markgross@thegnar.org>

Applied to linux-pm/linux-next.

Thanks,
Rafael


> --
> Resend v4
> - Corrected changelog
> Changes from v3
> - The timeout value is expresses in us (1/1000000 sec), not ms (1/1000 sec).
> Changes from v2
> - Rebased to avoid merge conflict
> Chages from v1(RFC)
> - The semmantics of timeout changed. A timeout now means that the
>  corresponding qos-req object is being cancelled, not rolling back to
> the qos request state at the time of API call. With this changes,
> combined with the conventional update_request API, there exists up to
> only one qos request per qos-req object.
> - The timeout value is expressed in ms (1/1000 sec), not jiffies.
> - Style changes, removing unnecessary changes.
> - Bugfixes regarding pending timeout work.
> ---
>  include/linux/pm_qos.h |    4 +++
>  kernel/power/qos.c     |   50 ++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 54 insertions(+), 0 deletions(-)
> 
> diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
> index c8a541e..18689737 100644
> --- a/include/linux/pm_qos.h
> +++ b/include/linux/pm_qos.h
> @@ -8,6 +8,7 @@
>  #include <linux/notifier.h>
>  #include <linux/miscdevice.h>
>  #include <linux/device.h>
> +#include <linux/workqueue.h>
>  
>  enum {
>  	PM_QOS_RESERVED = 0,
> @@ -29,6 +30,7 @@ enum {
>  struct pm_qos_request {
>  	struct plist_node node;
>  	int pm_qos_class;
> +	struct delayed_work work; /* for pm_qos_update_request_timeout */
>  };
>  
>  struct dev_pm_qos_request {
> @@ -73,6 +75,8 @@ void pm_qos_add_request(struct pm_qos_request *req, int pm_qos_class,
>  			s32 value);
>  void pm_qos_update_request(struct pm_qos_request *req,
>  			   s32 new_value);
> +void pm_qos_update_request_timeout(struct pm_qos_request *req,
> +				   s32 new_value, unsigned long timeout_us);
>  void pm_qos_remove_request(struct pm_qos_request *req);
>  
>  int pm_qos_request(int pm_qos_class);
> diff --git a/kernel/power/qos.c b/kernel/power/qos.c
> index d6d6dbd..6a031e6 100644
> --- a/kernel/power/qos.c
> +++ b/kernel/power/qos.c
> @@ -230,6 +230,21 @@ int pm_qos_request_active(struct pm_qos_request *req)
>  EXPORT_SYMBOL_GPL(pm_qos_request_active);
>  
>  /**
> + * pm_qos_work_fn - the timeout handler of pm_qos_update_request_timeout
> + * @work: work struct for the delayed work (timeout)
> + *
> + * This cancels the timeout request by falling back to the default at timeout.
> + */
> +static void pm_qos_work_fn(struct work_struct *work)
> +{
> +	struct pm_qos_request *req = container_of(to_delayed_work(work),
> +						  struct pm_qos_request,
> +						  work);
> +
> +	pm_qos_update_request(req, PM_QOS_DEFAULT_VALUE);
> +}
> +
> +/**
>   * pm_qos_add_request - inserts new qos request into the list
>   * @req: pointer to a preallocated handle
>   * @pm_qos_class: identifies which list of qos request to use
> @@ -253,6 +268,7 @@ void pm_qos_add_request(struct pm_qos_request *req,
>  		return;
>  	}
>  	req->pm_qos_class = pm_qos_class;
> +	INIT_DELAYED_WORK(&req->work, pm_qos_work_fn);
>  	pm_qos_update_target(pm_qos_array[pm_qos_class]->constraints,
>  			     &req->node, PM_QOS_ADD_REQ, value);
>  }
> @@ -279,6 +295,9 @@ void pm_qos_update_request(struct pm_qos_request *req,
>  		return;
>  	}
>  
> +	if (delayed_work_pending(&req->work))
> +		cancel_delayed_work_sync(&req->work);
> +
>  	if (new_value != req->node.prio)
>  		pm_qos_update_target(
>  			pm_qos_array[req->pm_qos_class]->constraints,
> @@ -287,6 +306,34 @@ void pm_qos_update_request(struct pm_qos_request *req,
>  EXPORT_SYMBOL_GPL(pm_qos_update_request);
>  
>  /**
> + * pm_qos_update_request_timeout - modifies an existing qos request temporarily.
> + * @req : handle to list element holding a pm_qos request to use
> + * @new_value: defines the temporal qos request
> + * @timeout_us: the effective duration of this qos request in usecs.
> + *
> + * After timeout_us, this qos request is cancelled automatically.
> + */
> +void pm_qos_update_request_timeout(struct pm_qos_request *req, s32 new_value,
> +				   unsigned long timeout_us)
> +{
> +	if (!req)
> +		return;
> +	if (WARN(!pm_qos_request_active(req),
> +		 "%s called for unknown object.", __func__))
> +		return;
> +
> +	if (delayed_work_pending(&req->work))
> +		cancel_delayed_work_sync(&req->work);
> +
> +	if (new_value != req->node.prio)
> +		pm_qos_update_target(
> +			pm_qos_array[req->pm_qos_class]->constraints,
> +			&req->node, PM_QOS_UPDATE_REQ, new_value);
> +
> +	schedule_delayed_work(&req->work, usecs_to_jiffies(timeout_us));
> +}
> +
> +/**
>   * pm_qos_remove_request - modifies an existing qos request
>   * @req: handle to request list element
>   *
> @@ -305,6 +352,9 @@ void pm_qos_remove_request(struct pm_qos_request *req)
>  		return;
>  	}
>  
> +	if (delayed_work_pending(&req->work))
> +		cancel_delayed_work_sync(&req->work);
> +
>  	pm_qos_update_target(pm_qos_array[req->pm_qos_class]->constraints,
>  			     &req->node, PM_QOS_REMOVE_REQ,
>  			     PM_QOS_DEFAULT_VALUE);
>