This is a note to let you know that I've just added the patch titled PM / devfreq: Fix available_governor sysfs to the 4.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: pm-devfreq-fix-available_governor-sysfs.patch and it can be found in the queue-4.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From bcf23c79c4e46130701370af4383b61a3cba755c Mon Sep 17 00:00:00 2001 From: Chanwoo Choi <cw00.choi@xxxxxxxxxxx> Date: Tue, 31 Jan 2017 15:38:16 +0900 Subject: PM / devfreq: Fix available_governor sysfs From: Chanwoo Choi <cw00.choi@xxxxxxxxxxx> 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@xxxxxxxxxxx> Signed-off-by: MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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); Patches currently in stable-queue which might be from cw00.choi@xxxxxxxxxxx are queue-4.10/pm-devfreq-fix-wrong-trans_stat-of-passive-devfreq-device.patch queue-4.10/pm-devfreq-fix-available_governor-sysfs.patch