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Subject[PATCH v3 2/3] devfreq: add clearing transitions stats
Date
Add clearing transition table and time in states devfreq statistics
by writing 0 (zero) to trans_stat file in devfreq sysfs. An example use
is like following:

echo 0 > /sys/class/devfreq/devfreqX/trans_stat

Signed-off-by: Kamil Konieczny <k.konieczny@samsung.com>
---
Changes in v3:
- add checks for zero in input and clear stats only when zero is written
to trans_stats
- change documentation of trans_stat in sysfs

Changes in v2:
- instead of creating new sysfs file, add new functionality to trans_stat
and clear stats when anything is writen to it
---
Documentation/ABI/testing/sysfs-class-devfreq | 11 +++++---
drivers/devfreq/devfreq.c | 27 ++++++++++++++++++-
2 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq
index 75897e2fde43..9758eb85ade3 100644
--- a/Documentation/ABI/testing/sysfs-class-devfreq
+++ b/Documentation/ABI/testing/sysfs-class-devfreq
@@ -55,12 +55,15 @@ What: /sys/class/devfreq/.../trans_stat
Date: October 2012
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
- This ABI shows the statistics of devfreq behavior on a
- specific device. It shows the time spent in each state and
- the number of transitions between states.
+ This ABI shows or clears the statistics of devfreq behavior
+ on a specific device. It shows the time spent in each state
+ and the number of transitions between states.
In order to activate this ABI, the devfreq target device
driver should provide the list of available frequencies
- with its profile.
+ with its profile. If need to reset the statistics of devfreq
+ behavior on a specific device, enter 0(zero) to 'trans_stat'
+ as following:
+ echo 0 > /sys/class/devfreq/.../trans_stat

What: /sys/class/devfreq/.../userspace/set_freq
Date: September 2011
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index abecadeb3dc2..218eb64d7f28 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -1478,7 +1478,32 @@ static ssize_t trans_stat_show(struct device *dev,
devfreq->total_trans);
return len;
}
-static DEVICE_ATTR_RO(trans_stat);
+
+static ssize_t trans_stat_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct devfreq *df = to_devfreq(dev);
+ unsigned int cnt = df->profile->max_state;
+ int err, value;
+
+ if (cnt == 0)
+ return count;
+
+ err = kstrtoint(buf, 10, &value);
+ if (err || value != 0)
+ return count;
+
+ mutex_lock(&df->lock);
+ memset(df->time_in_state, 0, cnt * sizeof(u64));
+ memset(df->trans_table, 0, cnt * cnt * sizeof(int));
+ df->last_stat_updated = get_jiffies_64();
+ df->total_trans = 0;
+ mutex_unlock(&df->lock);
+
+ return count;
+}
+static DEVICE_ATTR_RW(trans_stat);

static struct attribute *devfreq_attrs[] = {
&dev_attr_name.attr,
--
2.24.0
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