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Message-Id: <201203280003.59332.rjw@sisk.pl>
Date: Wed, 28 Mar 2012 00:03:59 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: MyungJoo Ham <myungjoo.ham@...sung.com>
Cc: linux-pm@...r.kernel.org, Mark Gross <markgross@...gnar.org>,
kyungmin.park@...sung.com, myungjoo.ham@...il.com,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] PM / QoS: add pm_qos_update_request_timeout API
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?
> 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@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
> Acked-by: Mark Gross <markgross@...gnar.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
> --
> 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);
>
--
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