From: Chanwoo Choi <cw00.choi@samsung.com>
To: Leonard Crestez <leonard.crestez@nxp.com>,
MyungJoo Ham <myungjoo.ham@samsung.com>,
Kyungmin Park <kyungmin.park@samsung.com>,
Matthias Kaehlcke <mka@chromium.org>
Cc: "Artur Świgoń" <a.swigon@partner.samsung.com>,
"Abel Vesa" <abel.vesa@nxp.com>,
"Saravana Kannan" <saravanak@google.com>,
linux-pm@vger.kernel.org,
"Viresh Kumar" <viresh.kumar@linaro.org>,
"NXP Linux Team" <linux-imx@nxp.com>,
"Krzysztof Kozlowski" <krzk@kernel.org>,
"Lukasz Luba" <l.luba@partner.samsung.com>,
"Alexandre Bailon" <abailon@baylibre.com>,
"Georgi Djakov" <georgi.djakov@linaro.org>,
linux-arm-kernel@lists.infradead.org,
"Jacky Bai" <ping.bai@nxp.com>
Subject: Re: [PATCH v8 5/6] PM / devfreq: Add PM QoS support
Date: Wed, 25 Sep 2019 11:15:36 +0900 [thread overview]
Message-ID: <40885624-8f11-4eea-d5bf-d6bb50fa44dd@samsung.com> (raw)
In-Reply-To: <58fdd2c226a4e76a3d9427baab7dd5c23af842ab.1569319738.git.leonard.crestez@nxp.com>
On 19. 9. 24. 오후 7:11, 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>
> Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
> ---
> drivers/devfreq/devfreq.c | 75 +++++++++++++++++++++++++++++++++++++++
> include/linux/devfreq.h | 5 +++
> 2 files changed, 80 insertions(+)
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index eee403e70c84..784f3e40536a 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;
> + unsigned long qos_min_freq, qos_max_freq;
>
> lockdep_assert_held(&devfreq->lock);
>
> /*
> * Init min/max frequency from freq table.
> @@ -125,10 +129,18 @@ static void get_freq_range(struct devfreq *devfreq,
> } else {
> *min_freq = freq_table[devfreq->profile->max_state - 1];
> *max_freq = freq_table[0];
> }
>
> + /* constraints from PM QoS */
As I commented on patch4,
'constraints' -> 'Constraint' because first verb have to be used
as the sigular verbs.
I prefer to use following comments:
/* Constraint minimum/maximum frequency from PM QoS constraints */
> + 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_MIN_FREQUENCY);
> + *min_freq = max(*min_freq, HZ_PER_KHZ * qos_min_freq);
> + *max_freq = min(*max_freq, HZ_PER_KHZ * qos_max_freq);
> +
> /* constraints from sysfs */
> *min_freq = max(*min_freq, devfreq->min_freq);
> *max_freq = min(*max_freq, devfreq->max_freq);
>
> /* constraints from OPP interface */
> @@ -606,10 +618,49 @@ static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
> mutex_unlock(&devfreq->lock);
>
> return ret;
> }
>
> +/**
> + * 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 for PM QoS constraints (%d)\n",
Is it not over 80 char?
> + 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.
> @@ -620,10 +671,15 @@ static void devfreq_dev_release(struct device *dev)
>
> mutex_lock(&devfreq_list_lock);
> list_del(&devfreq->node);
> mutex_unlock(&devfreq_list_lock);
>
> + dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_max,
> + DEV_PM_QOS_MAX_FREQUENCY);
> + dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_min,
> + DEV_PM_QOS_MIN_FREQUENCY);
> +
Just print error with dev_err() without stopping the release step.
I prefer to handle the return value if kernel API provides
the error code.
> if (devfreq->profile->exit)
> devfreq->profile->exit(devfreq->dev.parent);
>
> kfree(devfreq->time_in_state);
> kfree(devfreq->trans_table);
> @@ -733,10 +789,28 @@ struct devfreq *devfreq_add_device(struct device *dev,
> if (err) {
> put_device(&devfreq->dev);
> goto err_out;
> }
>
> + /*
> + * Register notifiers for updates to min/max_freq after device is
> + * initialized (and we can handle notifications) but before the
> + * governor is started (which should do an initial enforcement of
> + * constraints).
> + */
My previous comment is not enough why I prefer to remove it. Sorry.
Actually, until now, the devfreq_add_device() don't have the detailed
comments because the line code is not too long. But, at the present time,
devfreq_add_device() is too long. It means that the detailed comment
are necessary.
So, I'll add the detailed comment for each step of devfreq_add_device()
on separate patch to keep the same style. I'll send the patch to you
for the review.
> + 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",
> @@ -760,10 +834,11 @@ 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 c3cbc15fdf08..dac0dffeabb4 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;
>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
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next prev parent reply other threads:[~2019-09-25 2:11 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20190924101140epcas1p4abeedf42f223e65f58c88a0ddf1e4e56@epcas1p4.samsung.com>
2019-09-24 10:11 ` [PATCH v8 0/6] PM / devfreq: Add dev_pm_qos support Leonard Crestez
2019-09-24 10:11 ` [PATCH v8 1/6] PM / devfreq: Don't fail devfreq_dev_release if not in list Leonard Crestez
2019-09-24 10:11 ` [PATCH v8 2/6] PM / devfreq: Move more initialization before registration Leonard Crestez
2019-09-25 1:46 ` Chanwoo Choi
2019-09-24 10:11 ` [PATCH v8 3/6] PM / devfreq: Don't take lock in devfreq_add_device Leonard Crestez
2019-09-24 10:11 ` [PATCH v8 4/6] PM / devfreq: Introduce get_freq_range helper Leonard Crestez
2019-09-25 1:37 ` Chanwoo Choi
2019-09-25 20:55 ` Leonard Crestez
2019-09-26 1:06 ` Chanwoo Choi
2019-09-26 14:03 ` Leonard Crestez
2019-09-24 10:11 ` [PATCH v8 5/6] PM / devfreq: Add PM QoS support Leonard Crestez
2019-09-24 19:11 ` Matthias Kaehlcke
2019-09-24 19:22 ` Leonard Crestez
2019-09-25 2:17 ` Chanwoo Choi
2019-09-25 19:40 ` Leonard Crestez
2019-09-26 1:08 ` Chanwoo Choi
2019-09-25 2:15 ` Chanwoo Choi [this message]
2019-09-25 16:06 ` Matthias Kaehlcke
2019-09-25 21:18 ` Leonard Crestez
2019-09-26 1:12 ` Chanwoo Choi
2019-09-26 13:43 ` Leonard Crestez
2019-09-27 1:49 ` Chanwoo Choi
2019-09-30 13:16 ` Leonard Crestez
2019-09-30 21:42 ` Chanwoo Choi
2019-10-01 9:39 ` Leonard Crestez
2019-10-01 21:55 ` Chanwoo Choi
2019-09-26 1:19 ` Chanwoo Choi
2019-09-30 12:43 ` Leonard Crestez
2019-09-30 21:21 ` Chanwoo Choi
2019-09-24 10:11 ` [PATCH v8 6/6] PM / devfreq: Use PM QoS for sysfs min/max_freq Leonard Crestez
2019-09-25 2:41 ` Chanwoo Choi
2019-09-25 16:45 ` Matthias Kaehlcke
2019-09-26 1:25 ` Chanwoo Choi
2019-09-26 16:04 ` Matthias Kaehlcke
2019-09-27 1:58 ` Chanwoo Choi
2019-09-25 22:11 ` Leonard Crestez
2019-09-26 1:26 ` Chanwoo Choi
2019-09-25 1:44 ` [PATCH v8 0/6] PM / devfreq: Add dev_pm_qos support Chanwoo Choi
2019-09-25 19:37 ` Leonard Crestez
[not found] ` <CGME20190924101139epcas1p4c6799a5de9bdb4e90abb74de1e881388@epcms1p4>
2019-09-25 1:58 ` [PATCH v8 2/6] PM / devfreq: Move more initialization before registration MyungJoo Ham
2019-09-25 19:33 ` Leonard Crestez
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