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 7/8] PM / devfreq: Add PM QoS support
Date: Wed, 2 Oct 2019 15:22:04 -0700 [thread overview]
Message-ID: <20191002222204.GH87296@google.com> (raw)
In-Reply-To: <f538324afaeaef3256b3ea997e67562e940c2e3c.1570044052.git.leonard.crestez@nxp.com>
On Wed, Oct 02, 2019 at 10:25:10PM +0300, Leonard Crestez wrote:
> Register notifiers with the PM QoS framework in order to respond to
> requests for DEV_PM_QOS_MIN_FREQUENCY and DEV_PM_QOS_MAX_FREQUENCY.
>
> No notifiers are added by this patch but PM QoS constraints can be
> imposed externally (for example from other devices).
>
> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> ---
> drivers/devfreq/devfreq.c | 78 +++++++++++++++++++++++++++++++++++++++
> include/linux/devfreq.h | 5 +++
> 2 files changed, 83 insertions(+)
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 2d63692903ff..46f699b84a22 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -22,15 +22,18 @@
> #include <linux/platform_device.h>
> #include <linux/list.h>
> #include <linux/printk.h>
> #include <linux/hrtimer.h>
> #include <linux/of.h>
> +#include <linux/pm_qos.h>
> #include "governor.h"
>
> #define CREATE_TRACE_POINTS
> #include <trace/events/devfreq.h>
>
> +#define HZ_PER_KHZ 1000
> +
> static struct class *devfreq_class;
>
> /*
> * devfreq core provides delayed work based load monitoring helper
> * functions. Governors can use these or can implement their own
> @@ -109,10 +112,11 @@ static unsigned long find_available_max_freq(struct devfreq *devfreq)
> static void get_freq_range(struct devfreq *devfreq,
> unsigned long *min_freq,
> unsigned long *max_freq)
> {
> unsigned long *freq_table = devfreq->profile->freq_table;
> + s32 qos_min_freq, qos_max_freq;
>
> lockdep_assert_held(&devfreq->lock);
>
> /*
> * Initialize minimum/maximum frequency from freq table.
> @@ -125,10 +129,20 @@ static void get_freq_range(struct devfreq *devfreq,
> } else {
> *min_freq = freq_table[devfreq->profile->max_state - 1];
> *max_freq = freq_table[0];
> }
>
> + /* Apply constraints from PM QoS */
> + qos_min_freq = dev_pm_qos_read_value(devfreq->dev.parent,
> + DEV_PM_QOS_MIN_FREQUENCY);
> + qos_max_freq = dev_pm_qos_read_value(devfreq->dev.parent,
> + DEV_PM_QOS_MAX_FREQUENCY);
> + *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 */
> @@ -608,24 +622,75 @@ static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
> err);
>
> return NOTIFY_OK;
> }
>
> +/**
> + * qos_notifier_call() - Common handler for QoS constraints.
> + * @devfreq: the devfreq instance.
> + */
> +static int qos_notifier_call(struct devfreq *devfreq)
> +{
> + int err;
> +
> + mutex_lock(&devfreq->lock);
> + err = update_devfreq(devfreq);
> + mutex_unlock(&devfreq->lock);
> + if (err)
> + dev_err(devfreq->dev.parent,
> + "failed to update frequency from PM QoS (%d)\n",
> + err);
> +
> + return NOTIFY_OK;
> +}
> +
> +/**
> + * qos_min_notifier_call() - Callback for QoS min_freq changes.
> + * @nb: Should be devfreq->nb_min
> + */
> +static int qos_min_notifier_call(struct notifier_block *nb,
> + unsigned long val, void *ptr)
> +{
> + return qos_notifier_call(container_of(nb, struct devfreq, nb_min));
> +}
> +
> +/**
> + * qos_max_notifier_call() - Callback for QoS max_freq changes.
> + * @nb: Should be devfreq->nb_max
> + */
> +static int qos_max_notifier_call(struct notifier_block *nb,
> + unsigned long val, void *ptr)
> +{
> + return qos_notifier_call(container_of(nb, struct devfreq, nb_max));
> +}
> +
> /**
> * devfreq_dev_release() - Callback for struct device to release the device.
> * @dev: the devfreq device
> *
> * Remove devfreq from the list and release its resources.
> */
> static void devfreq_dev_release(struct device *dev)
> {
> struct devfreq *devfreq = to_devfreq(dev);
> + int err;
>
> mutex_lock(&devfreq_list_lock);
> list_del(&devfreq->node);
> mutex_unlock(&devfreq_list_lock);
>
> + err = dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_max,
> + DEV_PM_QOS_MAX_FREQUENCY);
> + if (err)
> + dev_warn(dev->parent, "Failed to remove DEV_PM_QOS_MAX_FREQUENCY notifier: %d\n",
> + err);
> + err = dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_min,
> + DEV_PM_QOS_MIN_FREQUENCY);
> + if (err)
> + dev_warn(dev->parent, "Failed to remove DEV_PM_QOS_MIN_FREQUENCY notifier: %d\n",
> + err);
> +
> if (devfreq->profile->exit)
> devfreq->profile->exit(devfreq->dev.parent);
>
I was concerned there might be a race where the notifier is still
running, but I confirmed that dev_pm_qos_mtx is held by
dev_pm_qos_remove_notifier() and also when the notifiers are called.
> kfree(devfreq->time_in_state);
> kfree(devfreq->trans_table);
> @@ -735,10 +800,22 @@ struct devfreq *devfreq_add_device(struct device *dev,
> if (err) {
> put_device(&devfreq->dev);
> goto err_out;
> }
>
> + devfreq->nb_min.notifier_call = qos_min_notifier_call;
> + err = dev_pm_qos_add_notifier(devfreq->dev.parent, &devfreq->nb_min,
> + DEV_PM_QOS_MIN_FREQUENCY);
> + if (err)
> + goto err_devfreq;
> +
> + devfreq->nb_max.notifier_call = qos_max_notifier_call;
> + err = dev_pm_qos_add_notifier(devfreq->dev.parent, &devfreq->nb_max,
> + DEV_PM_QOS_MAX_FREQUENCY);
> + if (err)
> + goto err_devfreq;
> +
> mutex_lock(&devfreq_list_lock);
>
> governor = try_then_request_governor(devfreq->governor_name);
> if (IS_ERR(governor)) {
> dev_err(dev, "%s: Unable to find governor for the device\n",
> @@ -762,10 +839,11 @@ struct devfreq *devfreq_add_device(struct device *dev,
>
> return devfreq;
>
> err_init:
> mutex_unlock(&devfreq_list_lock);
> +err_devfreq:
> devfreq_remove_device(devfreq);
> return ERR_PTR(err);
>
> err_dev:
> /*
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index 2bae9ed3c783..8b92ccbd1962 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -134,10 +134,12 @@ struct devfreq_dev_profile {
> * @total_trans: Number of devfreq transitions
> * @trans_table: Statistics of devfreq transitions
> * @time_in_state: Statistics of devfreq states
> * @last_stat_updated: The last time stat updated
> * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
> + * @nb_min: Notifier block for DEV_PM_QOS_MIN_FREQUENCY
> + * @nb_max: Notifier block for DEV_PM_QOS_MAX_FREQUENCY
> *
> * This structure stores the devfreq information for a give device.
> *
> * Note that when a governor accesses entries in struct devfreq in its
> * functions except for the context of callbacks defined in struct
> @@ -176,10 +178,13 @@ struct devfreq {
> unsigned int *trans_table;
> unsigned long *time_in_state;
> unsigned long last_stat_updated;
>
> struct srcu_notifier_head transition_notifier_list;
> +
> + struct notifier_block nb_min;
> + struct notifier_block nb_max;
> };
>
> struct devfreq_freqs {
> unsigned long old;
> unsigned long new;
> --
> 2.17.1
>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
next prev parent reply other threads:[~2019-10-02 22:22 UTC|newest]
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 [this message]
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
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
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