Commit 04fa9c80 authored by Matthias Kaehlcke's avatar Matthias Kaehlcke Committed by Daniel Lezcano
Browse files

thermal: devfreq_cooling: Use PM QoS to set frequency limits 



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.

The switch from disabling OPPs to PM QoS introduces a subtle behavioral
change in case of conflicting requests (min > max): PM QoS gives
precedence to the MIN_FREQUENCY request, while higher OPPs disabled
with dev_pm_opp_disable() would override MIN_FREQUENCY.

Signed-off-by: default avatarMatthias Kaehlcke <mka@chromium.org>
Reviewed-by: default avatarLukasz Luba <lukasz.luba@arm.com>
Reviewed-by: default avatarChanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20200318114548.19916-4-lukasz.luba@arm.com
parent 44fc7322

drivers/thermal/devfreq_cooling.c

+23 −47
Original line number Diff line number Diff line
@@ -24,10 +24,12 @@ 
#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 HZ_PER_KHZ		1000

#define SCALE_ERROR_MITIGATION	100



static DEFINE_IDA(devfreq_ida);
@@ -54,6 +56,8 @@ static DEFINE_IDA(devfreq_ida); 
 *		The 'res_util' range is from 100 to (power_table[state] * 100)

 *		for the corresponding 'state'.

 * @capped_state:	index to cooling state with in dynamic power budget

 * @req_max_freq:	PM QoS request for limiting the maximum frequency

 *			of the devfreq device.

 */

struct devfreq_cooling_device {

	int id;
@@ -66,49 +70,9 @@ struct devfreq_cooling_device { 
	struct devfreq_cooling_power *power_ops;

	u32 res_util;

	int capped_state;

	struct dev_pm_qos_request req_max_freq;

};



/**

 * 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)

{
@@ -135,7 +99,7 @@ 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;
@@ -145,9 +109,10 @@ 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;
@@ -530,9 +495,15 @@ of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df, 
	if (err)

		goto free_dfc;



	err = ida_simple_get(&devfreq_ida, 0, 0, GFP_KERNEL);

	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 free_tables;



	err = ida_simple_get(&devfreq_ida, 0, 0, GFP_KERNEL);

	if (err < 0)

		goto remove_qos_req;

	dfc->id = err;



	snprintf(dev_name, sizeof(dev_name), "thermal-devfreq-%d", dfc->id);
@@ -553,6 +524,10 @@ 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);
@@ -601,6 +576,7 @@ 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);

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