Linux-PM Archive on lore.kernel.org
 help / color / Atom feed
From: Matthias Kaehlcke <mka@chromium.org>
To: Leonard Crestez <leonard.crestez@nxp.com>
Cc: "Chanwoo Choi" <cw00.choi@samsung.com>,
	"MyungJoo Ham" <myungjoo.ham@samsung.com>,
	"Kyungmin Park" <kyungmin.park@samsung.com>,
	"Artur Świgoń" <a.swigon@partner.samsung.com>,
	"Saravana Kannan" <saravanak@google.com>,
	"Krzysztof Kozlowski" <krzk@kernel.org>,
	"Alexandre Bailon" <abailon@baylibre.com>,
	"Georgi Djakov" <georgi.djakov@linaro.org>,
	"Abel Vesa" <abel.vesa@nxp.com>, "Jacky Bai" <ping.bai@nxp.com>,
	"Viresh Kumar" <viresh.kumar@linaro.org>,
	"Lukasz Luba" <l.luba@partner.samsung.com>,
	"NXP Linux Team" <linux-imx@nxp.com>,
	linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v9 8/8] PM / devfreq: Use PM QoS for sysfs min/max_freq
Date: Fri, 4 Oct 2019 10:05:12 -0700
Message-ID: <20191004170512.GM87296@google.com> (raw)
In-Reply-To: <62584a1e5c08d0f9254df505883fb220ba53d57b.1570044052.git.leonard.crestez@nxp.com>

On Wed, Oct 02, 2019 at 10:25:11PM +0300, Leonard Crestez wrote:
> Switch the handling of min_freq and max_freq from sysfs to use the
> dev_pm_qos_request interface.
> 
> Since PM QoS handles frequencies as kHz this change reduces the
> precision of min_freq and max_freq. This shouldn't introduce problems
> because frequencies which are not an integer number of kHz are likely
> not an integer number of Hz either.
> 
> Try to ensure compatibility by rounding min values down and rounding
> max values up.
> 
> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
> ---
>  drivers/devfreq/devfreq.c | 63 ++++++++++++++++++++++++++++-----------
>  include/linux/devfreq.h   |  9 +++---
>  2 files changed, 51 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 46f699b84a22..4ff5fbc4ee85 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -139,14 +139,10 @@ static void get_freq_range(struct devfreq *devfreq,
>  	*min_freq = max(*min_freq, (unsigned long)HZ_PER_KHZ * qos_min_freq);
>  	if (qos_max_freq != PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE)
>  		*max_freq = min(*max_freq,
>  				(unsigned long)HZ_PER_KHZ * qos_max_freq);
>  
> -	/* Apply constraints from sysfs */
> -	*min_freq = max(*min_freq, devfreq->min_freq);
> -	*max_freq = min(*max_freq, devfreq->max_freq);
> -
>  	/* Apply constraints from OPP interface */
>  	*min_freq = max(*min_freq, devfreq->scaling_min_freq);
>  	/* scaling_max_freq can be zero on error */
>  	if (devfreq->scaling_max_freq)
>  		*max_freq = min(*max_freq, devfreq->scaling_max_freq);
> @@ -690,10 +686,18 @@ static void devfreq_dev_release(struct device *dev)
>  			 err);
>  
>  	if (devfreq->profile->exit)
>  		devfreq->profile->exit(devfreq->dev.parent);
>  
> +	err = dev_pm_qos_remove_request(&devfreq->user_max_freq_req);
> +	if (err)
> +		dev_warn(dev->parent, "Failed to remove DEV_PM_QOS_MAX_FREQUENCY request: %d\n",
> +			 err);
> +	err = dev_pm_qos_remove_request(&devfreq->user_min_freq_req);
> +	if (err)
> +		dev_warn(dev->parent, "Failed to remove DEV_PM_QOS_MIN_FREQUENCY request: %d\n",
> +			 err);
>  	kfree(devfreq->time_in_state);
>  	kfree(devfreq->trans_table);
>  	mutex_destroy(&devfreq->lock);
>  	kfree(devfreq);
>  }
> @@ -758,18 +762,26 @@ struct devfreq *devfreq_add_device(struct device *dev,
>  	devfreq->scaling_min_freq = find_available_min_freq(devfreq);
>  	if (!devfreq->scaling_min_freq) {
>  		err = -EINVAL;
>  		goto err_dev;
>  	}
> -	devfreq->min_freq = devfreq->scaling_min_freq;
>  
>  	devfreq->scaling_max_freq = find_available_max_freq(devfreq);
>  	if (!devfreq->scaling_max_freq) {
>  		err = -EINVAL;
>  		goto err_dev;
>  	}
> -	devfreq->max_freq = devfreq->scaling_max_freq;
> +
> +	err = dev_pm_qos_add_request(dev, &devfreq->user_min_freq_req,
> +				     DEV_PM_QOS_MIN_FREQUENCY, 0);
> +	if (err < 0)
> +		goto err_dev;
> +	err = dev_pm_qos_add_request(dev, &devfreq->user_max_freq_req,
> +				     DEV_PM_QOS_MAX_FREQUENCY,
> +				     PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE);
> +	if (err < 0)
> +		goto err_dev;
>  
>  	devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
>  	atomic_set(&devfreq->suspend_count, 0);
>  
>  	devfreq->trans_table = kzalloc(
> @@ -848,10 +860,16 @@ struct devfreq *devfreq_add_device(struct device *dev,
>  err_dev:
>  	/*
>  	 * Cleanup path for errors that happen before registration.
>  	 * Otherwise we rely on devfreq_dev_release.
>  	 */
> +	if (dev_pm_qos_request_active(&devfreq->user_max_freq_req))
> +		if (dev_pm_qos_remove_request(&devfreq->user_max_freq_req))
> +			dev_warn(dev, "Failed to remove DEV_PM_QOS_MAX_FREQUENCY request\n");
> +	if (dev_pm_qos_request_active(&devfreq->user_min_freq_req))
> +		if (dev_pm_qos_remove_request(&devfreq->user_min_freq_req))
> +			dev_warn(dev, "Failed to remove DEV_PM_QOS_MIN_FREQUENCY request\n");
>  	kfree(devfreq->time_in_state);
>  	kfree(devfreq->trans_table);
>  	kfree(devfreq);
>  err_out:
>  	return ERR_PTR(err);
> @@ -1392,14 +1410,15 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>  
>  	ret = sscanf(buf, "%lu", &value);
>  	if (ret != 1)
>  		return -EINVAL;
>  
> -	mutex_lock(&df->lock);
> -	df->min_freq = value;
> -	update_devfreq(df);
> -	mutex_unlock(&df->lock);
> +	/* Round down to kHz for PM QoS */
> +	ret = dev_pm_qos_update_request(&df->user_min_freq_req,
> +					value / HZ_PER_KHZ);
> +	if (ret < 0)
> +		return ret;
>  
>  	return count;
>  }
>  
>  static ssize_t min_freq_show(struct device *dev, struct device_attribute *attr,
> @@ -1424,18 +1443,28 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
>  
>  	ret = sscanf(buf, "%lu", &value);
>  	if (ret != 1)
>  		return -EINVAL;
>  
> -	mutex_lock(&df->lock);
> -
> -	if (!value)
> -		value = ULONG_MAX;
> +	/*
> +	 * PM QoS frequencies are in kHz so we need to convert. Convert by
> +	 * rounding upwards so that the acceptable interval never shrinks.
> +	 *
> +	 * For example if the user writes "666666666" to sysfs this value will
> +	 * be converted to 666667 kHz and back to 666667000 Hz before an OPP
> +	 * lookup, this ensures that an OPP of 666666666Hz is still accepted.
> +	 *
> +	 * A value of zero means "no limit".
> +	 */
> +	if (value)
> +		value = DIV_ROUND_UP(value, HZ_PER_KHZ);
> +	else
> +		value = PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE;
>  
> -	df->max_freq = value;
> -	update_devfreq(df);
> -	mutex_unlock(&df->lock);
> +	ret = dev_pm_qos_update_request(&df->user_max_freq_req, value);
> +	if (ret < 0)
> +		return ret;
>  
>  	return count;
>  }
>  static DEVICE_ATTR_RW(min_freq);
>  
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index 8b92ccbd1962..fb376b5b7281 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -11,10 +11,11 @@
>  #define __LINUX_DEVFREQ_H__
>  
>  #include <linux/device.h>
>  #include <linux/notifier.h>
>  #include <linux/pm_opp.h>
> +#include <linux/pm_qos.h>
>  
>  #define DEVFREQ_NAME_LEN 16
>  
>  /* DEVFREQ governor name */
>  #define DEVFREQ_GOV_SIMPLE_ONDEMAND	"simple_ondemand"
> @@ -121,12 +122,12 @@ struct devfreq_dev_profile {
>   *		devfreq.nb to the corresponding register notifier call chain.
>   * @work:	delayed work for load monitoring.
>   * @previous_freq:	previously configured frequency value.
>   * @data:	Private data of the governor. The devfreq framework does not
>   *		touch this.
> - * @min_freq:	Limit minimum frequency requested by user (0: none)
> - * @max_freq:	Limit maximum frequency requested by user (0: none)
> + * @user_min_freq_req:	PM QoS minimum frequency request from user (via sysfs)
> + * @user_max_freq_req:	PM QoS maximum frequency request from user (via sysfs)
>   * @scaling_min_freq:	Limit minimum frequency requested by OPP interface
>   * @scaling_max_freq:	Limit maximum frequency requested by OPP interface
>   * @stop_polling:	 devfreq polling status of a device.
>   * @suspend_freq:	 frequency of a device set during suspend phase.
>   * @resume_freq:	 frequency of a device set in resume phase.
> @@ -161,12 +162,12 @@ struct devfreq {
>  	unsigned long previous_freq;
>  	struct devfreq_dev_status last_status;
>  
>  	void *data; /* private data for governors */
>  
> -	unsigned long min_freq;
> -	unsigned long max_freq;
> +	struct dev_pm_qos_request user_min_freq_req;
> +	struct dev_pm_qos_request user_max_freq_req;
>  	unsigned long scaling_min_freq;
>  	unsigned long scaling_max_freq;
>  	bool stop_polling;
>  
>  	unsigned long suspend_freq;
> -- 
> 2.17.1
> 

Tested-by: Matthias Kaehlcke <mka@chromium.org>

  reply index

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-02 19:25 [PATCH v9 0/8] PM / devfreq: Add dev_pm_qos support Leonard Crestez
2019-10-02 19:25 ` [PATCH v9 1/8] PM / devfreq: Don't fail devfreq_dev_release if not in list Leonard Crestez
2019-10-02 19:25 ` [PATCH v9 2/8] PM / devfreq: Fix devfreq_notifier_call returning errno Leonard Crestez
2019-10-02 21:24   ` Matthias Kaehlcke
2019-10-02 23:47     ` Leonard Crestez
2019-10-31  2:29   ` Chanwoo Choi
2019-10-02 19:25 ` [PATCH v9 3/8] PM / devfreq: Set scaling_max_freq to max on OPP notifier error Leonard Crestez
2019-10-02 21:33   ` Matthias Kaehlcke
2019-10-31  2:21   ` Chanwoo Choi
2019-10-02 19:25 ` [PATCH v9 4/8] PM / devfreq: Move more initialization before registration Leonard Crestez
2019-10-31  3:15   ` Chanwoo Choi
2019-10-31 13:31     ` Leonard Crestez
2019-11-01  8:31       ` Chanwoo Choi
2019-11-01 14:36         ` Leonard Crestez
2019-10-02 19:25 ` [PATCH v9 5/8] PM / devfreq: Don't take lock in devfreq_add_device Leonard Crestez
2019-10-02 19:25 ` [PATCH v9 6/8] PM / devfreq: Introduce get_freq_range helper Leonard Crestez
2019-10-03 18:19   ` Matthias Kaehlcke
2019-10-03 19:16     ` Leonard Crestez
2019-10-03 19:36       ` Matthias Kaehlcke
2019-10-11 18:29     ` Matthias Kaehlcke
2019-10-31  2:44       ` Chanwoo Choi
2019-10-31  2:42   ` Chanwoo Choi
2019-10-31 13:12     ` Leonard Crestez
2019-10-02 19:25 ` [PATCH v9 7/8] PM / devfreq: Add PM QoS support Leonard Crestez
2019-10-02 22:22   ` Matthias Kaehlcke
2019-10-04 17:04   ` Matthias Kaehlcke
2019-10-31  3:01   ` Chanwoo Choi
2019-10-31 13:21     ` Leonard Crestez
2019-10-02 19:25 ` [PATCH v9 8/8] PM / devfreq: Use PM QoS for sysfs min/max_freq Leonard Crestez
2019-10-04 17:05   ` Matthias Kaehlcke [this message]
2019-10-31  3:10   ` Chanwoo Choi
2019-10-23 14:06 ` [PATCH v9 0/8] PM / devfreq: Add dev_pm_qos support Leonard Crestez
2019-10-23 16:34   ` Matthias Kaehlcke
2019-10-24 16:21     ` Leonard Crestez

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191004170512.GM87296@google.com \
    --to=mka@chromium.org \
    --cc=a.swigon@partner.samsung.com \
    --cc=abailon@baylibre.com \
    --cc=abel.vesa@nxp.com \
    --cc=cw00.choi@samsung.com \
    --cc=georgi.djakov@linaro.org \
    --cc=krzk@kernel.org \
    --cc=kyungmin.park@samsung.com \
    --cc=l.luba@partner.samsung.com \
    --cc=leonard.crestez@nxp.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-imx@nxp.com \
    --cc=linux-pm@vger.kernel.org \
    --cc=myungjoo.ham@samsung.com \
    --cc=ping.bai@nxp.com \
    --cc=saravanak@google.com \
    --cc=viresh.kumar@linaro.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-PM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-pm/0 linux-pm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-pm linux-pm/ https://lore.kernel.org/linux-pm \
		linux-pm@vger.kernel.org
	public-inbox-index linux-pm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-pm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git