From 27dbc542f651ed09de910f274b32634904103774 Mon Sep 17 00:00:00 2001 From: Leonard Crestez Date: Thu, 5 Dec 2019 12:05:07 +0200 Subject: [PATCH] PM / devfreq: Use PM QoS for sysfs min/max_freq Switch the handling of min_freq and max_freq from sysfs to use the dev_pm_qos_request interface. Since PM QoS handles frequencies as kHz this change reduces the precision of min_freq and max_freq. This shouldn't introduce problems because frequencies which are not an integer number of kHz are likely not an integer number of Hz either. Try to ensure compatibility by rounding min values down and rounding max values up. Signed-off-by: Leonard Crestez Acked-by: Chanwoo Choi Reviewed-by: Matthias Kaehlcke Tested-by: Matthias Kaehlcke [cw00.choi: Return -EAGAIN instead of -EINVAL if dev_pm_qos is inactive] Signed-off-by: Chanwoo Choi --- drivers/devfreq/devfreq.c | 76 ++++++++++++++++++++++++++++++--------- include/linux/devfreq.h | 9 ++--- 2 files changed, 64 insertions(+), 21 deletions(-) diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index f6e272085448..57f6944d65a6 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -141,10 +141,6 @@ static void get_freq_range(struct devfreq *devfreq, *max_freq = min(*max_freq, (unsigned long)HZ_PER_KHZ * qos_max_freq); - /* Apply constraints from sysfs */ - *min_freq = max(*min_freq, devfreq->min_freq); - *max_freq = min(*max_freq, devfreq->max_freq); - /* Apply constraints from OPP interface */ *min_freq = max(*min_freq, devfreq->scaling_min_freq); *max_freq = min(*max_freq, devfreq->scaling_max_freq); @@ -705,6 +701,19 @@ static void devfreq_dev_release(struct device *dev) dev_warn(dev->parent, "Failed to remove min_freq notifier: %d\n", err); + if (dev_pm_qos_request_active(&devfreq->user_max_freq_req)) { + err = dev_pm_qos_remove_request(&devfreq->user_max_freq_req); + if (err) + dev_warn(dev->parent, + "Failed to remove max_freq request: %d\n", err); + } + if (dev_pm_qos_request_active(&devfreq->user_min_freq_req)) { + err = dev_pm_qos_remove_request(&devfreq->user_min_freq_req); + if (err) + dev_warn(dev->parent, + "Failed to remove min_freq request: %d\n", err); + } + if (devfreq->profile->exit) devfreq->profile->exit(devfreq->dev.parent); @@ -778,7 +787,6 @@ struct devfreq *devfreq_add_device(struct device *dev, err = -EINVAL; goto err_dev; } - devfreq->min_freq = devfreq->scaling_min_freq; devfreq->scaling_max_freq = find_available_max_freq(devfreq); if (!devfreq->scaling_max_freq) { @@ -786,7 +794,6 @@ struct devfreq *devfreq_add_device(struct device *dev, err = -EINVAL; goto err_dev; } - devfreq->max_freq = devfreq->scaling_max_freq; devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev); atomic_set(&devfreq->suspend_count, 0); @@ -827,6 +834,16 @@ struct devfreq *devfreq_add_device(struct device *dev, mutex_unlock(&devfreq->lock); + err = dev_pm_qos_add_request(dev, &devfreq->user_min_freq_req, + DEV_PM_QOS_MIN_FREQUENCY, 0); + if (err < 0) + goto err_devfreq; + err = dev_pm_qos_add_request(dev, &devfreq->user_max_freq_req, + DEV_PM_QOS_MAX_FREQUENCY, + PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE); + if (err < 0) + goto err_devfreq; + devfreq->nb_min.notifier_call = qos_min_notifier_call; err = dev_pm_qos_add_notifier(devfreq->dev.parent, &devfreq->nb_min, DEV_PM_QOS_MIN_FREQUENCY); @@ -1412,14 +1429,22 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr, unsigned long value; int ret; + /* + * Protect against theoretical sysfs writes between + * device_add and dev_pm_qos_add_request + */ + if (!dev_pm_qos_request_active(&df->user_min_freq_req)) + return -EAGAIN; + ret = sscanf(buf, "%lu", &value); if (ret != 1) return -EINVAL; - mutex_lock(&df->lock); - df->min_freq = value; - update_devfreq(df); - mutex_unlock(&df->lock); + /* Round down to kHz for PM QoS */ + ret = dev_pm_qos_update_request(&df->user_min_freq_req, + value / HZ_PER_KHZ); + if (ret < 0) + return ret; return count; } @@ -1444,18 +1469,35 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr, unsigned long value; int ret; + /* + * Protect against theoretical sysfs writes between + * device_add and dev_pm_qos_add_request + */ + if (!dev_pm_qos_request_active(&df->user_max_freq_req)) + return -EINVAL; + ret = sscanf(buf, "%lu", &value); if (ret != 1) return -EINVAL; - mutex_lock(&df->lock); + /* + * PM QoS frequencies are in kHz so we need to convert. Convert by + * rounding upwards so that the acceptable interval never shrinks. + * + * For example if the user writes "666666666" to sysfs this value will + * be converted to 666667 kHz and back to 666667000 Hz before an OPP + * lookup, this ensures that an OPP of 666666666Hz is still accepted. + * + * A value of zero means "no limit". + */ + if (value) + value = DIV_ROUND_UP(value, HZ_PER_KHZ); + else + value = PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE; - if (!value) - value = ULONG_MAX; - - df->max_freq = value; - update_devfreq(df); - mutex_unlock(&df->lock); + ret = dev_pm_qos_update_request(&df->user_max_freq_req, value); + if (ret < 0) + return ret; return count; } diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h index 8b92ccbd1962..fb376b5b7281 100644 --- a/include/linux/devfreq.h +++ b/include/linux/devfreq.h @@ -13,6 +13,7 @@ #include #include #include +#include #define DEVFREQ_NAME_LEN 16 @@ -123,8 +124,8 @@ struct devfreq_dev_profile { * @previous_freq: previously configured frequency value. * @data: Private data of the governor. The devfreq framework does not * touch this. - * @min_freq: Limit minimum frequency requested by user (0: none) - * @max_freq: Limit maximum frequency requested by user (0: none) + * @user_min_freq_req: PM QoS minimum frequency request from user (via sysfs) + * @user_max_freq_req: PM QoS maximum frequency request from user (via sysfs) * @scaling_min_freq: Limit minimum frequency requested by OPP interface * @scaling_max_freq: Limit maximum frequency requested by OPP interface * @stop_polling: devfreq polling status of a device. @@ -163,8 +164,8 @@ struct devfreq { void *data; /* private data for governors */ - unsigned long min_freq; - unsigned long max_freq; + struct dev_pm_qos_request user_min_freq_req; + struct dev_pm_qos_request user_max_freq_req; unsigned long scaling_min_freq; unsigned long scaling_max_freq; bool stop_polling;