From: Matthias Kaehlcke <mka@chromium.org>
To: Leonard Crestez <leonard.crestez@nxp.com>
Cc: "Artur Świgoń" <a.swigon@partner.samsung.com>,
"Jacky Bai" <ping.bai@nxp.com>,
linux-pm@vger.kernel.org,
"Viresh Kumar" <viresh.kumar@linaro.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
"Chanwoo Choi" <cw00.choi@samsung.com>,
"Kyungmin Park" <kyungmin.park@samsung.com>,
"MyungJoo Ham" <myungjoo.ham@samsung.com>,
"NXP Linux Team" <linux-imx@nxp.com>,
"Georgi Djakov" <georgi.djakov@linaro.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 2/2] PM / devfreq: Use PM QoS for sysfs min/max_freq
Date: Thu, 5 Dec 2019 10:02:53 -0800 [thread overview]
Message-ID: <20191205180253.GN228856@google.com> (raw)
In-Reply-To: <2b9eeb4e576c45269c01826f13c7811b876faa57.1575540224.git.leonard.crestez@nxp.com>
On Thu, Dec 05, 2019 at 12:05:07PM +0200, 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>
> Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
> ---
> drivers/devfreq/devfreq.c | 76 ++++++++++++++++++++++++++++++---------
> include/linux/devfreq.h | 9 ++---
> 2 files changed, 64 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index e8b943fc4259..bcb286509547 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);
> *max_freq = min(*max_freq, devfreq->scaling_max_freq);
>
> if (*min_freq > *max_freq)
> @@ -703,10 +699,23 @@ static void devfreq_dev_release(struct device *dev)
> DEV_PM_QOS_MIN_FREQUENCY);
> if (err && err != -ENOENT)
> dev_warn(dev->parent,
> "Failed to remove min_freq notifier: %d\n", err);
>
> + if (dev_pm_qos_request_active(&devfreq->user_max_freq_req)) {
> + err = dev_pm_qos_remove_request(&devfreq->user_max_freq_req);
> + if (err)
> + dev_warn(dev->parent,
> + "Failed to remove max_freq request: %d\n", err);
> + }
> + if (dev_pm_qos_request_active(&devfreq->user_min_freq_req)) {
> + err = dev_pm_qos_remove_request(&devfreq->user_min_freq_req);
> + if (err)
> + dev_warn(dev->parent,
> + "Failed to remove min_freq request: %d\n", err);
> + }
> +
> if (devfreq->profile->exit)
> devfreq->profile->exit(devfreq->dev.parent);
>
> mutex_destroy(&devfreq->lock);
> kfree(devfreq);
> @@ -776,19 +785,17 @@ struct devfreq *devfreq_add_device(struct device *dev,
> if (!devfreq->scaling_min_freq) {
> mutex_unlock(&devfreq->lock);
> 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) {
> mutex_unlock(&devfreq->lock);
> err = -EINVAL;
> goto err_dev;
> }
> - devfreq->max_freq = devfreq->scaling_max_freq;
>
> devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
> atomic_set(&devfreq->suspend_count, 0);
>
> dev_set_name(&devfreq->dev, "devfreq%d",
> @@ -825,10 +832,20 @@ struct devfreq *devfreq_add_device(struct device *dev,
>
> srcu_init_notifier_head(&devfreq->transition_notifier_list);
>
> mutex_unlock(&devfreq->lock);
>
> + err = dev_pm_qos_add_request(dev, &devfreq->user_min_freq_req,
> + DEV_PM_QOS_MIN_FREQUENCY, 0);
> + if (err < 0)
> + goto err_devfreq;
> + 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_devfreq;
> +
> 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;
> @@ -1418,18 +1435,26 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
> {
> struct devfreq *df = to_devfreq(dev);
> unsigned long value;
> int ret;
>
> + /*
> + * Protect against theoretical sysfs writes between
> + * device_add and dev_pm_qos_add_request
> + */
> + if (!dev_pm_qos_request_active(&df->user_min_freq_req))
> + return -EINVAL;
The error code -EINVAL is a bit misleading. I guess it's not super
important, especially since this is a very rare case. In case you
re-spin you could consider returning -EAGAIN ('Resource temporarily
unavailable') in this case from min/max_freq_store/show()
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Tested-by: Matthias Kaehlcke <mka@chromium.org>
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-12-05 18:03 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-05 10:05 [PATCH v2 0/2] PM / devfreq: Add dev_pm_qos support Leonard Crestez
2019-12-05 10:05 ` [PATCH v2 1/2] PM / devfreq: Add PM QoS support Leonard Crestez
2019-12-05 17:48 ` Matthias Kaehlcke
2019-12-10 1:24 ` Leonard Crestez
2019-12-05 10:05 ` [PATCH v2 2/2] PM / devfreq: Use PM QoS for sysfs min/max_freq Leonard Crestez
2019-12-05 18:02 ` Matthias Kaehlcke [this message]
2019-12-06 2:38 ` Chanwoo Choi
2019-12-05 10:12 ` [PATCH v2 0/2] PM / devfreq: Add dev_pm_qos support Rafael J. Wysocki
2019-12-05 10:44 ` Leonard Crestez
2019-12-06 3:27 ` Chanwoo Choi
2019-12-06 4:54 ` Chanwoo Choi
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=20191205180253.GN228856@google.com \
--to=mka@chromium.org \
--cc=a.swigon@partner.samsung.com \
--cc=cw00.choi@samsung.com \
--cc=georgi.djakov@linaro.org \
--cc=kyungmin.park@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=rjw@rjwysocki.net \
--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).