From: Chanwoo Choi <cw00.choi@samsung.com>
To: Leonard Crestez <leonard.crestez@nxp.com>,
Matthias Kaehlcke <mka@chromium.org>
Cc: "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>,
dl-linux-imx <linux-imx@nxp.com>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v8 5/6] PM / devfreq: Add PM QoS support
Date: Thu, 26 Sep 2019 10:19:15 +0900 [thread overview]
Message-ID: <10b7f567-3d07-d4b0-b555-48c03a26461e@samsung.com> (raw)
In-Reply-To: <VI1PR04MB7023573BA3D5C5D521DB689CEE870@VI1PR04MB7023.eurprd04.prod.outlook.com>
On 19. 9. 26. 오전 6:18, Leonard Crestez wrote:
> On 25.09.2019 05:11, Chanwoo Choi wrote:
>> 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.
>
> Already discussed for another patch; I will modify to "Apply constraints
> from PM QoS" instead.
>
>> 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?
>
> Yes but coding style explicitly forbids breaking strings.
I want to make it within 80 char. How about following comment?
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.
>>> @@ -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.
>
> This is very likely to result in merge conflicts, maybe wait for my
> series to go in first?
>
>>> + 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
next prev parent reply other threads:[~2019-09-26 1:14 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
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 [this message]
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
Reply instructions:
You may reply publicly 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=10b7f567-3d07-d4b0-b555-48c03a26461e@samsung.com \
--to=cw00.choi@samsung.com \
--cc=a.swigon@partner.samsung.com \
--cc=abailon@baylibre.com \
--cc=abel.vesa@nxp.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=mka@chromium.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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).