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    SubjectRe: [PATCH v4] PM / QoS: add pm_qos_update_request_timeout API
    From
    2012/3/28 Rafael J. Wysocki <rjw@sisk.pl>:
    > On Tuesday, March 27, 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 jiffies.
    >> After 1000 jiffies, the QoS request thru req is rolled back to the
    >> request status when pm_qos_update_request_timeout() was called. If there
    >> were another pm_qos_update_request(req, x) during the 1000 jiffies, this
    >> new request with value x will override as this is another request on the
    >> same req handle.
    >
    > Can you please update the above part of the changelog to reflect the
    > fact that microseconds are the new timeout units?

    Sure, I've just sent another.

    >
    >> 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>
    >
    > It is kind of too late for the 3.4 merge window, so I'd prefer to keep that
    > for the v3.5 cycle, unless you urgently need it in v3.4, in which case please
    > let me know.
    >
    > Thanks,
    > Rafael
    >

    Could you please put it with 3.4 if possible? We want to use this
    feature with 3.4.

    Thanks a lot.


    Cheers!
    MyungJoo.

    >
    >> --
    >> 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);
    >>
    >



    --
    MyungJoo Ham, Ph.D.
    Mobile Software Platform Lab, DMC Business, Samsung Electronics
    --
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