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PM / devfreq: Restart previous governor if new governor fails to start

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If the new governor fails to start, switch back to old governor so that the
devfreq state is not left in some weird limbo.

[Myungjoo: assume fatal on revert failure and set df->governor to NULL]
Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
This commit is contained in:
Saravana Kannan 2019-03-11 15:36:30 +05:30 committed by MyungJoo Ham
parent 1d1397c3ec
commit bc658bef97
1 changed files with 14 additions and 2 deletions
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16
drivers/devfreq/devfreq.c
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@ -1124,7 +1124,7 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
struct devfreq *df = to_devfreq(dev); struct devfreq *df = to_devfreq(dev);
int ret; int ret;
char str_governor[DEVFREQ_NAME_LEN + 1]; char str_governor[DEVFREQ_NAME_LEN + 1];
struct devfreq_governor *governor; const struct devfreq_governor *governor, *prev_governor;
ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor); ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
if (ret != 1) if (ret != 1)
@ -1153,12 +1153,24 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
goto out; goto out;
} }
} }
prev_governor = df->governor;
df->governor = governor; df->governor = governor;
strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN); strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL); ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
if (ret) if (ret) {
dev_warn(dev, "%s: Governor %s not started(%d)\n", dev_warn(dev, "%s: Governor %s not started(%d)\n",
__func__, df->governor->name, ret); __func__, df->governor->name, ret);
df->governor = prev_governor;
strncpy(df->governor_name, prev_governor->name,
DEVFREQ_NAME_LEN);
ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
if (ret) {
dev_err(dev,
"%s: reverting to Governor %s failed (%d)\n",
__func__, df->governor_name, ret);
df->governor = NULL;
}
}
out: out:
mutex_unlock(&devfreq_list_lock); mutex_unlock(&devfreq_list_lock);