linux-kernel - Re: [PATCH] thermal/drivers/cpuidle_cooling: Change the set_cur

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Date:   Thu, 17 Sep 2020 19:15:32 +0800
From:   "zhuguangqing83" <zhuguangqing83@...il.com>
To:     "'Daniel Lezcano'" <daniel.lezcano@...aro.org>,
        <amit.kachhap@...il.com>, <viresh.kumar@...aro.org>,
        <javi.merino@...nel.org>, <rui.zhang@...el.com>,
        <amitk@...nel.org>, <zhuguangqing@...omi.com>
Cc:     <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] thermal/drivers/cpuidle_cooling: Change the set_cur_state function


> > From: zhuguangqing <zhuguangqing@...omi.com>
> >
> > In the function cpuidle_cooling_set_cur_state(), if current_state is
> > not equal to state and both current_state and state are greater than
> > 0(scene 4 as follows), then maybe it should stop->start or restart
> > idle_inject.
> 
> Sorry, I don't get it.
> 
> It is an update of the state, why do we need to restart the idle
> injection ? The state change will be automatically take into account by
> the idle injection code at the new injection cycle.
> 

Thanks for your comments.

For example, we call cpuidle_cooling_set_cur_state() twice, first time
the input parameter state is 20, second time the input parameter state
is 30.

In current code, in the second call of cpuidle_cooling_set_cur_state(),
current_state == 20, state == 30, then "if (current_state == 0 &&
state > 0)" is not satisfied, "else if (current_state > 0 && !state)"
is not satisfied either, so we just update idle_cdev->state to 30 and
idle_inject_set_duration to new injection cycle，but we do not call
idle injection code.

In the example mentioned above, we should call idle injection code. If
idle_inject_start() takes into account by the idle injection code at
the new injection cycle, then just calling idle_inject_start() is ok.
Otherwise, we need a restart or stop->start process to execute idle
injection code at the new state 30.

> > The scenes changed is as follows,
> >
> > scene    current_state    state    action
> >  1              0          >0       start
> >  2              0          0        do nothing
> >  3              >0         0        stop
> >  4        >0 && !=state    >0       stop->start or restart
> >  5        >0 && ==state    >0       do nothing
> >
> > Signed-off-by: zhuguangqing <zhuguangqing@...omi.com>
> > ---
> >  drivers/thermal/cpuidle_cooling.c | 10 ++++++++--
> >  1 file changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/thermal/cpuidle_cooling.c
> b/drivers/thermal/cpuidle_cooling.c
> > index 78e3e8238116..868919ad3dda 100644
> > --- a/drivers/thermal/cpuidle_cooling.c
> > +++ b/drivers/thermal/cpuidle_cooling.c
> > @@ -113,7 +113,7 @@ static int cpuidle_cooling_get_cur_state(struct
> > thermal_cooling_device *cdev,
> >  /**
> >   * cpuidle_cooling_set_cur_state - Set the current cooling state
> >   * @cdev: the thermal cooling device
> > - * @state: the target state
> > + * @state: the target state, max value is 100
> >   *
> >   * The function checks first if we are initiating the mitigation which
> >   * in turn wakes up all the idle injection tasks belonging to the idle
> > @@ -130,6 +130,9 @@ static int cpuidle_cooling_set_cur_state(struct
> > thermal_cooling_device *cdev,
> >  	unsigned long current_state = idle_cdev->state;
> >  	unsigned int runtime_us, idle_duration_us;
> >
> > +	if (state > 100 || current_state == state)
> > +		return 0;
> > +
> >  	idle_cdev->state = state;
> >
> >  	idle_inject_get_duration(ii_dev, &runtime_us, &idle_duration_us);
> > @@ -140,8 +143,11 @@ static int cpuidle_cooling_set_cur_state(struct
> > thermal_cooling_device *cdev,
> >
> >  	if (current_state == 0 && state > 0) {
> >  		idle_inject_start(ii_dev);
> > -	} else if (current_state > 0 && !state)  {
> > +	} else if (current_state > 0 && !state) {
> >  		idle_inject_stop(ii_dev);
> > +	} else {
> > +		idle_inject_stop(ii_dev);
> > +		idle_inject_start(ii_dev);
> >  	}
> >
> >  	return 0;
> >
> 
> 
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