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Message-ID: <CAJ0PZbR6WW66Nr=rMELQOURaeKDA3hqUsbEsn1kAgCfDpDa2zw@mail.gmail.com>
Date: Wed, 28 Mar 2012 10:53:19 +0900
From: MyungJoo Ham <myungjoo.ham@...sung.com>
To: "Rafael J. Wysocki" <rjw@...k.pl>
Cc: linux-pm@...r.kernel.org, Mark Gross <markgross@...gnar.org>,
kyungmin.park@...sung.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] PM / QoS: add pm_qos_update_request_timeout API
2012/3/28 Rafael J. Wysocki <rjw@...k.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@...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
>
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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