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

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

On Wednesday, March 28, 2012, MyungJoo Ham wrote:
> 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.

Can you please give any details, if possible?

Rafael


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