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Subject[PATCH 4.10 055/167] PM / devfreq: Fix available_governor sysfs
Date
4.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chanwoo Choi <cw00.choi@samsung.com>

commit bcf23c79c4e46130701370af4383b61a3cba755c upstream.

The devfreq using passive governor is not able to change the governor.
So, the user can not change the governor through 'available_governor' sysfs
entry. Also, the devfreq which don't use the passive governor is not able to
change to 'passive' governor on the fly.

Fixes: 996133119f57 ("PM / devfreq: Add new passive governor")
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/devfreq/devfreq.c | 31 +++++++++++++++++++++++++++----
drivers/devfreq/governor_passive.c | 1 +
include/linux/devfreq.h | 3 +++
3 files changed, 31 insertions(+), 4 deletions(-)

--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -939,6 +939,9 @@ static ssize_t governor_store(struct dev
if (df->governor == governor) {
ret = 0;
goto out;
+ } else if (df->governor->immutable || governor->immutable) {
+ ret = -EINVAL;
+ goto out;
}

if (df->governor) {
@@ -968,13 +971,33 @@ static ssize_t available_governors_show(
struct device_attribute *attr,
char *buf)
{
- struct devfreq_governor *tmp_governor;
+ struct devfreq *df = to_devfreq(d);
ssize_t count = 0;

mutex_lock(&devfreq_list_lock);
- list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
- count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
- "%s ", tmp_governor->name);
+
+ /*
+ * The devfreq with immutable governor (e.g., passive) shows
+ * only own governor.
+ */
+ if (df->governor->immutable) {
+ count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
+ "%s ", df->governor_name);
+ /*
+ * The devfreq device shows the registered governor except for
+ * immutable governors such as passive governor .
+ */
+ } else {
+ struct devfreq_governor *governor;
+
+ list_for_each_entry(governor, &devfreq_governor_list, node) {
+ if (governor->immutable)
+ continue;
+ count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
+ "%s ", governor->name);
+ }
+ }
+
mutex_unlock(&devfreq_list_lock);

/* Truncate the trailing space */
--- a/drivers/devfreq/governor_passive.c
+++ b/drivers/devfreq/governor_passive.c
@@ -179,6 +179,7 @@ static int devfreq_passive_event_handler

static struct devfreq_governor devfreq_passive = {
.name = "passive",
+ .immutable = 1,
.get_target_freq = devfreq_passive_get_target_freq,
.event_handler = devfreq_passive_event_handler,
};
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -104,6 +104,8 @@ struct devfreq_dev_profile {
* struct devfreq_governor - Devfreq policy governor
* @node: list node - contains registered devfreq governors
* @name: Governor's name
+ * @immutable: Immutable flag for governor. If the value is 1,
+ * this govenror is never changeable to other governor.
* @get_target_freq: Returns desired operating frequency for the device.
* Basically, get_target_freq will run
* devfreq_dev_profile.get_dev_status() to get the
@@ -121,6 +123,7 @@ struct devfreq_governor {
struct list_head node;

const char name[DEVFREQ_NAME_LEN];
+ const unsigned int immutable;
int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
int (*event_handler)(struct devfreq *devfreq,
unsigned int event, void *data);

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