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

[Saravana Kannan]

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

Signed-off-by: Saravana Kannan <skan...@codeaurora.org>
---
 drivers/devfreq/devfreq.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index bf3ea76..243253e 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -919,7 +919,7 @@ static ssize_t governor_store(struct device *dev, struct 
device_attribute *attr,
        struct devfreq *df = to_devfreq(dev);
        int ret;
        char str_governor[DEVFREQ_NAME_LEN + 1];
-       struct devfreq_governor *governor;
+       const struct devfreq_governor *governor, *prev_gov;
 
        ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
        if (ret != 1)
@@ -944,12 +944,17 @@ static ssize_t governor_store(struct device *dev, struct 
device_attribute *attr,
                        goto out;
                }
        }
+       prev_gov = df->governor;
        df->governor = governor;
        strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
        ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
-       if (ret)
+       if (ret) {
                dev_warn(dev, "%s: Governor %s not started(%d)\n",
                         __func__, df->governor->name, ret);
+               df->governor = prev_gov;
+               strncpy(df->governor_name, prev_gov->name, DEVFREQ_NAME_LEN);
+               df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
+       }
 out:
        mutex_unlock(&devfreq_list_lock);
 
-- 
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project