diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-devices-power | 27 | ||||
| -rw-r--r-- | Documentation/power/pm_qos_interface.txt | 59 | ||||
| -rw-r--r-- | drivers/base/power/qos.c | 144 | ||||
| -rw-r--r-- | drivers/base/power/sysfs.c | 65 | ||||
| -rw-r--r-- | include/linux/pm.h | 1 | ||||
| -rw-r--r-- | include/linux/pm_qos.h | 12 | ||||
| -rw-r--r-- | kernel/power/qos.c | 13 |
7 files changed, 277 insertions, 44 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-power b/Documentation/ABI/testing/sysfs-devices-power index efe449bdf811..7dbf96b724ed 100644 --- a/Documentation/ABI/testing/sysfs-devices-power +++ b/Documentation/ABI/testing/sysfs-devices-power @@ -187,7 +187,7 @@ Description: Not all drivers support this attribute. If it isn't supported, attempts to read or write it will yield I/O errors. -What: /sys/devices/.../power/pm_qos_latency_us +What: /sys/devices/.../power/pm_qos_resume_latency_us Date: March 2012 Contact: Rafael J. Wysocki <rjw@rjwysocki.net> Description: @@ -205,6 +205,31 @@ Description: This attribute has no effect on system-wide suspend/resume and hibernation. +What: /sys/devices/.../power/pm_qos_latency_tolerance_us +Date: January 2014 +Contact: Rafael J. Wysocki <rjw@rjwysocki.net> +Description: + The /sys/devices/.../power/pm_qos_latency_tolerance_us attribute + contains the PM QoS active state latency tolerance limit for the + given device in microseconds. That is the maximum memory access + latency the device can suffer without any visible adverse + effects on user space functionality. If that value is the + string "any", the latency does not matter to user space at all, + but hardware should not be allowed to set the latency tolerance + for the device automatically. + + Reading "auto" from this file means that the maximum memory + access latency for the device may be determined automatically + by the hardware as needed. Writing "auto" to it allows the + hardware to be switched to this mode if there are no other + latency tolerance requirements from the kernel side. + + This attribute is only present if the feature controlled by it + is supported by the hardware. + + This attribute has no effect on runtime suspend and resume of + devices and on system-wide suspend/resume and hibernation. + What: /sys/devices/.../power/pm_qos_no_power_off Date: September 2012 Contact: Rafael J. Wysocki <rjw@rjwysocki.net> diff --git a/Documentation/power/pm_qos_interface.txt b/Documentation/power/pm_qos_interface.txt index 22cb8f51182a..ed743bbad87c 100644 --- a/Documentation/power/pm_qos_interface.txt +++ b/Documentation/power/pm_qos_interface.txt @@ -88,17 +88,19 @@ node. 2. PM QoS per-device latency and flags framework -For each device, there are two lists of PM QoS requests. One is maintained -along with the aggregated target of resume latency value and the other is for -PM QoS flags. Values are updated in response to changes of the request list. +For each device, there are three lists of PM QoS requests. Two of them are +maintained along with the aggregated targets of resume latency and active +state latency tolerance (in microseconds) and the third one is for PM QoS flags. +Values are updated in response to changes of the request list. -Target resume latency value is simply the minimum of the request values held in -the parameter list elements. The PM QoS flags aggregate value is a gather -(bitwise OR) of all list elements' values. Two device PM QoS flags are defined -currently: PM_QOS_FLAG_NO_POWER_OFF and PM_QOS_FLAG_REMOTE_WAKEUP. +The target values of resume latency and active state latency tolerance are +simply the minimum of the request values held in the parameter list elements. +The PM QoS flags aggregate value is a gather (bitwise OR) of all list elements' +values. Two device PM QoS flags are defined currently: PM_QOS_FLAG_NO_POWER_OFF +and PM_QOS_FLAG_REMOTE_WAKEUP. -Note: the aggregated target value is implemented in such a way that reading the -aggregated value does not require any locking mechanism. +Note: The aggregated target values are implemented in such a way that reading +the aggregated value does not require any locking mechanism. From kernel mode the use of this interface is the following: @@ -177,3 +179,42 @@ The callback is called when the aggregated value for any device is changed int dev_pm_qos_remove_global_notifier(notifier): Removes the notification callback function from the global notification tree of the framework. + + +Active state latency tolerance + +This device PM QoS type is used to support systems in which hardware may switch +to energy-saving operation modes on the fly. In those systems, if the operation +mode chosen by the hardware attempts to save energy in an overly aggressive way, +it may cause excess latencies to be visible to software, causing it to miss +certain protocol requirements or target frame or sample rates etc. + +If there is a latency tolerance control mechanism for a given device available +to software, the .set_latency_tolerance callback in that device's dev_pm_info +structure should be populated. The routine pointed to by it is should implement +whatever is necessary to transfer the effective requirement value to the +hardware. + +Whenever the effective latency tolerance changes for the device, its +.set_latency_tolerance() callback will be executed and the effective value will +be passed to it. If that value is negative, which means that the list of +latency tolerance requirements for the device is empty, the callback is expected +to switch the underlying hardware latency tolerance control mechanism to an +autonomous mode if available. If that value is PM_QOS_LATENCY_ANY, in turn, and +the hardware supports a special "no requirement" setting, the callback is +expected to use it. That allows software to prevent the hardware from +automatically updating the device's latency tolerance in response to its power +state changes (e.g. during transitions from D3cold to D0), which generally may +be done in the autonomous latency tolerance control mode. + +If .set_latency_tolerance() is present for the device, sysfs attribute +pm_qos_latency_tolerance_us will be present in the devivce's power directory. +Then, user space can use that attribute to specify its latency tolerance +requirement for the device, if any. Writing "any" to it means "no requirement, +but do not let the hardware control latency tolerance" and writing "auto" to it +allows the hardware to be switched to the autonomous mode if there are no other +requirements from the kernel side in the device's list. + +Kernel code can use the functions described above along with the +DEV_PM_QOS_LATENCY_TOLERANCE device PM QoS type to add, remove and update +latency tolerance requirements for devices. diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c index c754e55f9dcb..84756f7f09d9 100644 --- a/drivers/base/power/qos.c +++ b/drivers/base/power/qos.c @@ -151,6 +151,14 @@ static int apply_constraint(struct dev_pm_qos_request *req, req); } break; + case DEV_PM_QOS_LATENCY_TOLERANCE: + ret = pm_qos_update_target(&qos->latency_tolerance, + &req->data.pnode, action, value); + if (ret) { + value = pm_qos_read_value(&qos->latency_tolerance); + req->dev->power.set_latency_tolerance(req->dev, value); + } + break; case DEV_PM_QOS_FLAGS: ret = pm_qos_update_flags(&qos->flags, &req->data.flr, action, value); @@ -194,6 +202,13 @@ static int dev_pm_qos_constraints_allocate(struct device *dev) c->type = PM_QOS_MIN; c->notifiers = n; + c = &qos->latency_tolerance; + plist_head_init(&c->list); + c->target_value = PM_QOS_LATENCY_TOLERANCE_DEFAULT_VALUE; + c->default_value = PM_QOS_LATENCY_TOLERANCE_DEFAULT_VALUE; + c->no_constraint_value = PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT; + c->type = PM_QOS_MIN; + INIT_LIST_HEAD(&qos->flags.list); spin_lock_irq(&dev->power.lock); @@ -247,6 +262,11 @@ void dev_pm_qos_constraints_destroy(struct device *dev) apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE); memset(req, 0, sizeof(*req)); } + c = &qos->latency_tolerance; + plist_for_each_entry_safe(req, tmp, &c->list, data.pnode) { + apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE); + memset(req, 0, sizeof(*req)); + } f = &qos->flags; list_for_each_entry_safe(req, tmp, &f->list, data.flr.node) { apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE); @@ -266,6 +286,40 @@ void dev_pm_qos_constraints_destroy(struct device *dev) mutex_unlock(&dev_pm_qos_sysfs_mtx); } +static bool dev_pm_qos_invalid_request(struct device *dev, + struct dev_pm_qos_request *req) +{ + return !req || (req->type == DEV_PM_QOS_LATENCY_TOLERANCE + && !dev->power.set_latency_tolerance); +} + +static int __dev_pm_qos_add_request(struct device *dev, + struct dev_pm_qos_request *req, + enum dev_pm_qos_req_type type, s32 value) +{ + int ret = 0; + + if (!dev || dev_pm_qos_invalid_request(dev, req)) + return -EINVAL; + + if (WARN(dev_pm_qos_request_active(req), + "%s() called for already added request\n", __func__)) + return -EINVAL; + + if (IS_ERR(dev->power.qos)) + ret = -ENODEV; + else if (!dev->power.qos) + ret = dev_pm_qos_constraints_allocate(dev); + + trace_dev_pm_qos_add_request(dev_name(dev), type, value); + if (!ret) { + req->dev = dev; + req->type = type; + ret = apply_constraint(req, PM_QOS_ADD_REQ, value); + } + return ret; +} + /** * dev_pm_qos_add_request - inserts new qos request into the list * @dev: target device for the constraint @@ -291,31 +345,11 @@ void dev_pm_qos_constraints_destroy(struct device *dev) int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req, enum dev_pm_qos_req_type type, s32 value) { - int ret = 0; - - if (!dev || !req) /*guard against callers passing in null */ - return -EINVAL; - - if (WARN(dev_pm_qos_request_active(req), - "%s() called for already added request\n", __func__)) - return -EINVAL; + int ret; mutex_lock(&dev_pm_qos_mtx); - - if (IS_ERR(dev->power.qos)) - ret = -ENODEV; - else if (!dev->power.qos) - ret = dev_pm_qos_constraints_allocate(dev); - - trace_dev_pm_qos_add_request(dev_name(dev), type, value); - if (!ret) { - req->dev = dev; - req->type = type; - ret = apply_constraint(req, PM_QOS_ADD_REQ, value); - } - + ret = __dev_pm_qos_add_request(dev, req, type, value); mutex_unlock(&dev_pm_qos_mtx); - return ret; } EXPORT_SYMBOL_GPL(dev_pm_qos_add_request); @@ -343,6 +377,7 @@ static int __dev_pm_qos_update_request(struct dev_pm_qos_request *req, switch(req->type) { case DEV_PM_QOS_RESUME_LATENCY: + case DEV_PM_QOS_LATENCY_TOLERANCE: curr_value = req->data.pnode.prio; break; case DEV_PM_QOS_FLAGS: @@ -563,6 +598,10 @@ static void __dev_pm_qos_drop_user_request(struct device *dev, req = dev->power.qos->resume_latency_req; dev->power.qos->resume_latency_req = NULL; break; + case DEV_PM_QOS_LATENCY_TOLERANCE: + req = dev->power.qos->latency_tolerance_req; + dev->power.qos->latency_tolerance_req = NULL; + break; case DEV_PM_QOS_FLAGS: req = dev->power.qos->flags_req; dev->power.qos->flags_req = NULL; @@ -768,6 +807,67 @@ int dev_pm_qos_update_flags(struct device *dev, s32 mask, bool set) pm_runtime_put(dev); return ret; } + +/** + * dev_pm_qos_get_user_latency_tolerance - Get user space latency tolerance. + * @dev: Device to obtain the user space latency tolerance for. + */ +s32 dev_pm_qos_get_user_latency_tolerance(struct device *dev) +{ + s32 ret; + + mutex_lock(&dev_pm_qos_mtx); + ret = IS_ERR_OR_NULL(dev->power.qos) + || !dev->power.qos->latency_tolerance_req ? + PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT : + dev->power.qos->latency_tolerance_req->data.pnode.prio; + mutex_unlock(&dev_pm_qos_mtx); + return ret; +} + +/** + * dev_pm_qos_update_user_latency_tolerance - Update user space latency tolerance. + * @dev: Device to update the user space latency tolerance for. + * @val: New user space latency tolerance for @dev (negative values disable). + */ +int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val) +{ + int ret; + + mutex_lock(&dev_pm_qos_mtx); + + if (IS_ERR_OR_NULL(dev->power.qos) + || !dev->power.qos->latency_tolerance_req) { + struct dev_pm_qos_request *req; + + if (val < 0) { + ret = -EINVAL; + goto out; + } + req = kzalloc(sizeof(*req), GFP_KERNEL); + if (!req) { + ret = -ENOMEM; + goto out; + } + ret = __dev_pm_qos_add_request(dev, req, DEV_PM_QOS_LATENCY_TOLERANCE, val); + if (ret < 0) { + kfree(req); + goto out; + } + dev->power.qos->latency_tolerance_req = req; + } else { + if (val < 0) { + __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY_TOLERANCE); + ret = 0; + } else { + ret = __dev_pm_qos_update_request(dev->power.qos->latency_tolerance_req, val); + } + } + + out: + mutex_unlock(&dev_pm_qos_mtx); + return ret; +} #else /* !CONFIG_PM_RUNTIME */ static void __dev_pm_qos_hide_latency_limit(struct device *dev) {} static void __dev_pm_qos_hide_flags(struct device *dev) {} diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c index 4e24955aac8a..95b181d1ca6d 100644 --- a/drivers/base/power/sysfs.c +++ b/drivers/base/power/sysfs.c @@ -246,6 +246,40 @@ static ssize_t pm_qos_resume_latency_store(struct device *dev, static DEVICE_ATTR(pm_qos_resume_latency_us, 0644, pm_qos_resume_latency_show, pm_qos_resume_latency_store); +static ssize_t pm_qos_latency_tolerance_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + s32 value = dev_pm_qos_get_user_latency_tolerance(dev); + + if (value < 0) + return sprintf(buf, "auto\n"); + else if (value == PM_QOS_LATENCY_ANY) + return sprintf(buf, "any\n"); + + return sprintf(buf, "%d\n", value); +} + +static ssize_t pm_qos_latency_tolerance_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t n) +{ + s32 value; + int ret; + + if (kstrtos32(buf, 0, &value)) { + if (!strcmp(buf, "auto") || !strcmp(buf, "auto\n")) + value = PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT; + else if (!strcmp(buf, "any") || !strcmp(buf, "any\n")) + value = PM_QOS_LATENCY_ANY; + } + ret = dev_pm_qos_update_user_latency_tolerance(dev, value); + return ret < 0 ? ret : n; +} + +static DEVICE_ATTR(pm_qos_latency_tolerance_us, 0644, + pm_qos_latency_tolerance_show, pm_qos_latency_tolerance_store); + static ssize_t pm_qos_no_power_off_show(struct device *dev, struct device_attribute *attr, char *buf) @@ -631,6 +665,17 @@ static struct attribute_group pm_qos_resume_latency_attr_group = { .attrs = pm_qos_resume_latency_attrs, }; +static struct attribute *pm_qos_latency_tolerance_attrs[] = { +#ifdef CONFIG_PM_RUNTIME + &dev_attr_pm_qos_latency_tolerance_us.attr, +#endif /* CONFIG_PM_RUNTIME */ + NULL, +}; +static struct attribute_group pm_qos_latency_tolerance_attr_group = { + .name = power_group_name, + .attrs = pm_qos_latency_tolerance_attrs, +}; + static struct attribute *pm_qos_flags_attrs[] = { #ifdef CONFIG_PM_RUNTIME &dev_attr_pm_qos_no_power_off.attr, @@ -656,18 +701,23 @@ int dpm_sysfs_add(struct device *dev) if (rc) goto err_out; } - if (device_can_wakeup(dev)) { rc = sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group); - if (rc) { - if (pm_runtime_callbacks_present(dev)) - sysfs_unmerge_group(&dev->kobj, - &pm_runtime_attr_group); - goto err_out; - } + if (rc) + goto err_runtime; + } + if (dev->power.set_latency_tolerance) { + rc = sysfs_merge_group(&dev->kobj, + &pm_qos_latency_tolerance_attr_group); + if (rc) + goto err_wakeup; } return 0; + err_wakeup: + sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group); + err_runtime: + sysfs_unmerge_group(&dev->kobj, &pm_runtime_attr_group); err_out: sysfs_remove_group(&dev->kobj, &pm_attr_group); return rc; @@ -710,6 +760,7 @@ void rpm_sysfs_remove(struct device *dev) void dpm_sysfs_remove(struct device *dev) { + sysfs_unmerge_group(&dev->kobj, &pm_qos_latency_tolerance_attr_group); dev_pm_qos_constraints_destroy(dev); rpm_sysfs_remove(dev); sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group); diff --git a/include/linux/pm.h b/include/linux/pm.h index 8c6583a53a06..db2be5f3e030 100644 --- a/include/linux/pm.h +++ b/include/linux/pm.h @@ -582,6 +582,7 @@ struct dev_pm_info { unsigned long accounting_timestamp; #endif struct pm_subsys_data *subsys_data; /* Owned by the subsystem. */ + void (*set_latency_tolerance)(struct device *, s32); struct dev_pm_qos *qos; }; diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h index 2d8ce50877d8..0b476019be55 100644 --- a/include/linux/pm_qos.h +++ b/include/linux/pm_qos.h @@ -33,6 +33,9 @@ enum pm_qos_flags_status { #define PM_QOS_NETWORK_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC) #define PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE 0 #define PM_QOS_RESUME_LATENCY_DEFAULT_VALUE 0 +#define PM_QOS_LATENCY_TOLERANCE_DEFAULT_VALUE 0 +#define PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT (-1) +#define PM_QOS_LATENCY_ANY ((s32)(~(__u32)0 >> 1)) #define PM_QOS_FLAG_NO_POWER_OFF (1 << 0) #define PM_QOS_FLAG_REMOTE_WAKEUP (1 << 1) @@ -50,6 +53,7 @@ struct pm_qos_flags_request { enum dev_pm_qos_req_type { DEV_PM_QOS_RESUME_LATENCY = 1, + DEV_PM_QOS_LATENCY_TOLERANCE, DEV_PM_QOS_FLAGS, }; @@ -89,8 +93,10 @@ struct pm_qos_flags { struct dev_pm_qos { struct pm_qos_constraints resume_latency; + struct pm_qos_constraints latency_tolerance; struct pm_qos_flags flags; struct dev_pm_qos_request *resume_latency_req; + struct dev_pm_qos_request *latency_tolerance_req; struct dev_pm_qos_request *flags_req; }; @@ -196,6 +202,8 @@ void dev_pm_qos_hide_latency_limit(struct device *dev); int dev_pm_qos_expose_flags(struct device *dev, s32 value); void dev_pm_qos_hide_flags(struct device *dev); int dev_pm_qos_update_flags(struct device *dev, s32 mask, bool set); +s32 dev_pm_qos_get_user_latency_tolerance(struct device *dev); +int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val); static inline s32 dev_pm_qos_requested_resume_latency(struct device *dev) { @@ -215,6 +223,10 @@ static inline int dev_pm_qos_expose_flags(struct device *dev, s32 value) static inline void dev_pm_qos_hide_flags(struct device *dev) {} static inline int dev_pm_qos_update_flags(struct device *dev, s32 m, bool set) { return 0; } +static inline s32 dev_pm_qos_get_user_latency_tolerance(struct device *dev) + { return PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT; } +static inline int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val) + { return 0; } static inline s32 dev_pm_qos_requested_resume_latency(struct device *dev) { return 0; } static inline s32 dev_pm_qos_requested_flags(struct device *dev) { return 0; } diff --git a/kernel/power/qos.c b/kernel/power/qos.c index e23ae38e647f..884b77058864 100644 --- a/kernel/power/qos.c +++ b/kernel/power/qos.c @@ -173,6 +173,7 @@ int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node, { unsigned long flags; int prev_value, curr_value, new_value; + int ret; spin_lock_irqsave(&pm_qos_lock, flags); prev_value = pm_qos_get_value(c); @@ -208,13 +209,15 @@ int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node, trace_pm_qos_update_target(action, prev_value, curr_value); if (prev_value != curr_value) { - blocking_notifier_call_chain(c->notifiers, - (unsigned long)curr_value, - NULL); - return 1; + ret = 1; + if (c->notifiers) + blocking_notifier_call_chain(c->notifiers, + (unsigned long)curr_value, + NULL); } else { - return 0; + ret = 0; } + return ret; } /** |
