Re: [PATCH v3] PM / QoS: add pm_qos_update_request_timeout API

[mark gross <markgross@thegnar.org>]

On Sat, Mar 24, 2012 at 09:41:22AM -0700, mark gross wrote:
> On Wed, Mar 07, 2012 at 02:06:18PM +0900, 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. 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>
> > ---
> > 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 values 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 0ee7caa..6f347fe 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,
> > @@ -33,6 +34,7 @@ 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 {
> > @@ -77,6 +79,8 @@ 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_ms);
> >  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 3e122db..8ac8eca 100644
> > --- a/kernel/power/qos.c
> > +++ b/kernel/power/qos.c
> > @@ -259,6 +259,21 @@ 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);
> this should be pm_qos_remove_request (req);
> 

on second thought your implementation is right.   pm_qos_remove_request
is wrong.

--mark


> 
> > +}
> > +
> > +/**
> >   * 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
> > @@ -282,6 +297,7 @@ 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);
> >  }
> > @@ -308,6 +324,9 @@ 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,
> > @@ -316,6 +335,34 @@ 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_ms: the effective duration of this qos request in msecs.
> > + *
> > + * After timeout_ms, this qos request is cancelled automatically.
> > + */
> > +void pm_qos_update_request_timeout(struct pm_qos_request *req, s32 new_value,
> > +				   unsigned long timeout_ms)
> > +{
> > +	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, msecs_to_jiffies(timeout_ms));
> > +}
> > +
> > +/**
> >   * pm_qos_remove_request - modifies an existing qos request
> >   * @req: handle to request list element
> >   *
> > @@ -334,6 +381,9 @@ 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);
> > -- 
> > 1.7.4.1
> >