linux-kernel - Re: [PATCH 1/2] thermal: devfreq_cooling: Use PM QoS to set frequency limits

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Message-ID: <bae154ef-cbe6-de24-26c7-a7d4338bd55e@samsung.com>
Date:   Mon, 13 Jan 2020 16:25:17 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Matthias Kaehlcke <mka@...omium.org>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Zhang Rui <rui.zhang@...el.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amit.kucheria@...durent.com>
Cc:     Leonard Crestez <leonard.crestez@....com>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH 1/2] thermal: devfreq_cooling: Use PM QoS to set
 frequency limits

Hi,

On 1/11/20 2:49 AM, Matthias Kaehlcke wrote:
> Now that devfreq supports limiting the frequency range of a device
> through PM QoS make use of it instead of disabling OPPs that should
> not be used.
> 
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> ---
> 
>  drivers/thermal/devfreq_cooling.c | 66 ++++++++++---------------------
>  1 file changed, 20 insertions(+), 46 deletions(-)
> 
> diff --git a/drivers/thermal/devfreq_cooling.c b/drivers/thermal/devfreq_cooling.c
> index ef59256887ff..3a63603afcf2 100644
> --- a/drivers/thermal/devfreq_cooling.c
> +++ b/drivers/thermal/devfreq_cooling.c
> @@ -24,11 +24,13 @@
>  #include <linux/idr.h>
>  #include <linux/slab.h>
>  #include <linux/pm_opp.h>
> +#include <linux/pm_qos.h>
>  #include <linux/thermal.h>
>  
>  #include <trace/events/thermal.h>
>  
> -#define SCALE_ERROR_MITIGATION 100
> +#define HZ_PER_KHZ		1000
> +#define SCALE_ERROR_MITIGATION	100
>  
>  static DEFINE_IDA(devfreq_ida);
>  
> @@ -65,49 +67,9 @@ struct devfreq_cooling_device {
>  	struct devfreq_cooling_power *power_ops;
>  	u32 res_util;
>  	int capped_state;
> +	struct dev_pm_qos_request req_max_freq;

Need to add the description of 'req_max_freq'.

>  };
>  
> -/**
> - * partition_enable_opps() - disable all opps above a given state
> - * @dfc:	Pointer to devfreq we are operating on
> - * @cdev_state:	cooling device state we're setting
> - *
> - * Go through the OPPs of the device, enabling all OPPs until
> - * @cdev_state and disabling those frequencies above it.
> - */
> -static int partition_enable_opps(struct devfreq_cooling_device *dfc,
> -				 unsigned long cdev_state)
> -{
> -	int i;
> -	struct device *dev = dfc->devfreq->dev.parent;
> -
> -	for (i = 0; i < dfc->freq_table_size; i++) {
> -		struct dev_pm_opp *opp;
> -		int ret = 0;
> -		unsigned int freq = dfc->freq_table[i];
> -		bool want_enable = i >= cdev_state ? true : false;
> -
> -		opp = dev_pm_opp_find_freq_exact(dev, freq, !want_enable);
> -
> -		if (PTR_ERR(opp) == -ERANGE)
> -			continue;
> -		else if (IS_ERR(opp))
> -			return PTR_ERR(opp);
> -
> -		dev_pm_opp_put(opp);
> -
> -		if (want_enable)
> -			ret = dev_pm_opp_enable(dev, freq);
> -		else
> -			ret = dev_pm_opp_disable(dev, freq);
> -
> -		if (ret)
> -			return ret;
> -	}
> -
> -	return 0;
> -}
> -
>  static int devfreq_cooling_get_max_state(struct thermal_cooling_device *cdev,
>  					 unsigned long *state)
>  {
> @@ -134,7 +96,7 @@ static int devfreq_cooling_set_cur_state(struct thermal_cooling_device *cdev,
>  	struct devfreq_cooling_device *dfc = cdev->devdata;
>  	struct devfreq *df = dfc->devfreq;
>  	struct device *dev = df->dev.parent;
> -	int ret;
> +	unsigned long freq;
>  
>  	if (state == dfc->cooling_state)
>  		return 0;
> @@ -144,9 +106,10 @@ static int devfreq_cooling_set_cur_state(struct thermal_cooling_device *cdev,
>  	if (state >= dfc->freq_table_size)
>  		return -EINVAL;
>  
> -	ret = partition_enable_opps(dfc, state);
> -	if (ret)
> -		return ret;
> +	freq = dfc->freq_table[state];
> +
> +	dev_pm_qos_update_request(&dfc->req_max_freq,
> +				  DIV_ROUND_UP(freq, HZ_PER_KHZ));
>  
>  	dfc->cooling_state = state;
>  
> @@ -529,6 +492,12 @@ of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
>  	if (err)
>  		goto free_dfc;
>  
> +	err = dev_pm_qos_add_request(df->dev.parent, &dfc->req_max_freq,
> +				     DEV_PM_QOS_MAX_FREQUENCY,
> +				     PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE);
> +	if (err < 0)
> +		goto remove_qos_req;

Jump 'free_table' instead of 'remove_qos_req'.

> +
>  	err = ida_simple_get(&devfreq_ida, 0, 0, GFP_KERNEL);
>  	if (err < 0)
>  		goto free_tables;

Jump remove_qos_req.

> @@ -552,6 +521,10 @@ of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
>  
>  release_ida:
>  	ida_simple_remove(&devfreq_ida, dfc->id);
> +
> +remove_qos_req:
> +	dev_pm_qos_remove_request(&dfc->req_max_freq);
> +
>  free_tables:
>  	kfree(dfc->power_table);
>  	kfree(dfc->freq_table);
> @@ -600,6 +573,7 @@ void devfreq_cooling_unregister(struct thermal_cooling_device *cdev)
>  
>  	thermal_cooling_device_unregister(dfc->cdev);
>  	ida_simple_remove(&devfreq_ida, dfc->id);
> +	dev_pm_qos_remove_request(&dfc->req_max_freq);
>  	kfree(dfc->power_table);
>  	kfree(dfc->freq_table);
>  
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics