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author | Enric Balletbo i Serra <enric.balletbo@collabora.com> | 2018-07-04 10:45:50 +0200 |
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committer | MyungJoo Ham <myungjoo.ham@samsung.com> | 2018-10-02 10:16:41 +0900 |
commit | 23c7b54ca1cd1797ef39169ab85e6d46f1c2d061 (patch) | |
tree | c04d424c2507228ea6cffb310f9b50b6b738296e /drivers/devfreq/devfreq.c | |
parent | 17b57b1883c1285f3d0dc2266e8f79286a7bef38 (diff) | |
download | linux-23c7b54ca1cd1797ef39169ab85e6d46f1c2d061.tar.gz linux-23c7b54ca1cd1797ef39169ab85e6d46f1c2d061.tar.bz2 linux-23c7b54ca1cd1797ef39169ab85e6d46f1c2d061.zip |
PM / devfreq: Fix devfreq_add_device() when drivers are built as modules.
When the devfreq driver and the governor driver are built as modules,
the call to devfreq_add_device() or governor_store() fails because the
governor driver is not loaded at the time the devfreq driver loads. The
devfreq driver has a build dependency on the governor but also should
have a runtime dependency. We need to make sure that the governor driver
is loaded before the devfreq driver.
This patch fixes this bug by adding a try_then_request_governor()
function. First tries to find the governor, and then, if it is not found,
it requests the module and tries again.
Fixes: 1b5c1be2c88e (PM / devfreq: map devfreq drivers to governor using name)
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Diffstat (limited to 'drivers/devfreq/devfreq.c')
-rw-r--r-- | drivers/devfreq/devfreq.c | 53 |
1 files changed, 49 insertions, 4 deletions
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 4c49bb1330b5..62ead442a872 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -11,6 +11,7 @@ */ #include <linux/kernel.h> +#include <linux/kmod.h> #include <linux/sched.h> #include <linux/errno.h> #include <linux/err.h> @@ -221,6 +222,49 @@ static struct devfreq_governor *find_devfreq_governor(const char *name) return ERR_PTR(-ENODEV); } +/** + * try_then_request_governor() - Try to find the governor and request the + * module if is not found. + * @name: name of the governor + * + * Search the list of devfreq governors and request the module and try again + * if is not found. This can happen when both drivers (the governor driver + * and the driver that call devfreq_add_device) are built as modules. + * devfreq_list_lock should be held by the caller. Returns the matched + * governor's pointer. + */ +static struct devfreq_governor *try_then_request_governor(const char *name) +{ + struct devfreq_governor *governor; + int err = 0; + + if (IS_ERR_OR_NULL(name)) { + pr_err("DEVFREQ: %s: Invalid parameters\n", __func__); + return ERR_PTR(-EINVAL); + } + WARN(!mutex_is_locked(&devfreq_list_lock), + "devfreq_list_lock must be locked."); + + governor = find_devfreq_governor(name); + if (IS_ERR(governor)) { + mutex_unlock(&devfreq_list_lock); + + if (!strncmp(name, DEVFREQ_GOV_SIMPLE_ONDEMAND, + DEVFREQ_NAME_LEN)) + err = request_module("governor_%s", "simpleondemand"); + else + err = request_module("governor_%s", name); + /* Restore previous state before return */ + mutex_lock(&devfreq_list_lock); + if (err) + return NULL; + + governor = find_devfreq_governor(name); + } + + return governor; +} + static int devfreq_notify_transition(struct devfreq *devfreq, struct devfreq_freqs *freqs, unsigned int state) { @@ -646,9 +690,8 @@ struct devfreq *devfreq_add_device(struct device *dev, mutex_unlock(&devfreq->lock); mutex_lock(&devfreq_list_lock); - list_add(&devfreq->node, &devfreq_list); - governor = find_devfreq_governor(devfreq->governor_name); + governor = try_then_request_governor(devfreq->governor_name); if (IS_ERR(governor)) { dev_err(dev, "%s: Unable to find governor for the device\n", __func__); @@ -664,12 +707,14 @@ struct devfreq *devfreq_add_device(struct device *dev, __func__); goto err_init; } + + list_add(&devfreq->node, &devfreq_list); + mutex_unlock(&devfreq_list_lock); return devfreq; err_init: - list_del(&devfreq->node); mutex_unlock(&devfreq_list_lock); device_unregister(&devfreq->dev); @@ -991,7 +1036,7 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, return -EINVAL; mutex_lock(&devfreq_list_lock); - governor = find_devfreq_governor(str_governor); + governor = try_then_request_governor(str_governor); if (IS_ERR(governor)) { ret = PTR_ERR(governor); goto out; |