From: Chanwoo Choi <cw00.choi@samsung.com>
To: Leonard Crestez <leonard.crestez@nxp.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" <linux-pm@vger.kernel.org>,
"Viresh Kumar" <viresh.kumar@linaro.org>,
dl-linux-imx <linux-imx@nxp.com>,
"Krzysztof Kozlowski" <krzk@kernel.org>,
"Lukasz Luba" <l.luba@partner.samsung.com>,
"Kyungmin Park" <kyungmin.park@samsung.com>,
"MyungJoo Ham" <myungjoo.ham@samsung.com>,
"Alexandre Bailon" <abailon@baylibre.com>,
"Georgi Djakov" <georgi.djakov@linaro.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"Jacky Bai" <ping.bai@nxp.com>
Subject: Re: [PATCH v8 6/6] PM / devfreq: Use PM QoS for sysfs min/max_freq
Date: Thu, 26 Sep 2019 10:26:59 +0900 [thread overview]
Message-ID: <61182b47-f207-d556-0043-81ed5b32a001@samsung.com> (raw)
In-Reply-To: <VI1PR04MB7023A6F6F6DF39FC273F020AEE870@VI1PR04MB7023.eurprd04.prod.outlook.com>
On 19. 9. 26. 오전 7:11, Leonard Crestez wrote:
> On 25.09.2019 05:36, Chanwoo Choi wrote:
>> On 19. 9. 24. 오후 7:11, 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 | 46 ++++++++++++++++++++++++---------------
>>> include/linux/devfreq.h | 9 ++++----
>>> 2 files changed, 33 insertions(+), 22 deletions(-)
>>>
>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>> index 784f3e40536a..8bb7efd821ab 100644
>>> --- a/drivers/devfreq/devfreq.c
>>> +++ b/drivers/devfreq/devfreq.c
>>> @@ -137,14 +137,10 @@ static void get_freq_range(struct devfreq *devfreq,
>>> 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 */
>>> *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);
>>> @@ -679,10 +675,12 @@ static void devfreq_dev_release(struct device *dev)
>>> DEV_PM_QOS_MIN_FREQUENCY);
>>>
>>> if (devfreq->profile->exit)
>>> devfreq->profile->exit(devfreq->dev.parent);
>>>
>>> + dev_pm_qos_remove_request(&devfreq->user_max_freq_req);
>>> + dev_pm_qos_remove_request(&devfreq->user_min_freq_req);
>>
>> Please check the return value if error happen, just print the err with dev_err()
>> without stopping the release steps.
>
> OK, will print errors
>
>>> kfree(devfreq->time_in_state);
>>> kfree(devfreq->trans_table);
>>> mutex_destroy(&devfreq->lock);
>>> kfree(devfreq);
>>> }
>>> @@ -747,18 +745,25 @@ 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, S32_MAX);
>>> + 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(
>>> @@ -843,10 +848,14 @@ 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))
>>> + dev_pm_qos_remove_request(&devfreq->user_max_freq_req);
>>
>> Please check the return value if error happen, just print the err with dev_err()
>> without stopping the release steps.
>
> OK, will print errors
>
>>
>> dev_err(... "failed to remove request of DEV_PM_QOS_MAX_FREQUENCY\n");
>>
>>> + if (dev_pm_qos_request_active(&devfreq->user_min_freq_req))
>>> + dev_pm_qos_remove_request(&devfreq->user_min_freq_req);
>>
>> dev_err(... "failed to remove request of DEV_PM_QOS_MIN_FREQUENCY\n");
>>
>>> kfree(devfreq->time_in_state);
>>> kfree(devfreq->trans_table);
>>> kfree(devfreq);
>>> err_out:
>>> return ERR_PTR(err);
>>> @@ -1407,14 +1416,15 @@ 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 */
>>
>> I prefer more detailed description as following:
>>
>> /*
>> * Round down to KHz to decide the proper minimum frequency
>> * which is closed to user request.
>> */
How about this comment? and with Matthias comment on other reply thread.
>>
>>
>>> + 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,
>>> @@ -1439,19 +1449,19 @@ 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);
>>> -
>>> - /* Interpret zero as "don't care" */
>>> - if (!value)
>>> - value = ULONG_MAX;
>>> + /* round up to kHz for PM QoS and interpret zero as "don't care" */
>>
>> I think that "don't care" comment style is not good.
>>
>> I referred to the Documentation/ABI/testing/sysfs-class-devfreq file.
>> I prefer more detailed description as following:
>> /*
>> * Round up to KHz to decide the proper maximum frequency
>> * which is closed to user request. If value is zero,
>> * the user does not care.
>> */
>
> OK, will update this comment
>
>>> + if (value)
>>> + value = DIV_ROUND_UP(value, HZ_PER_KHZ);
>>> + else
>>> + value = S32_MAX;
>>>
>>> - 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 dac0dffeabb4..7849fe4c666d 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 min frequency request from user (via sysfs)
>>
>> min -> minimum and then remove parenthesis as following:
>> PM QoS minimum frequency request by user via sysfs
>>
>>> + * @user_max_freq_req: PM QoS max frequency request from user (via sysfs)
>>
>> ditto. max -> maximum
>> PM QoS maximum frequency request by user via sysfs
>
> OK
Thanks.
>
>>> * @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;
>>>
>>
>>
>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
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next prev parent reply other threads:[~2019-09-26 1:22 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
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 [this message]
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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