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Date: Tue, 9 Oct 2012 20:37:16 -0700
From: mark gross <markgross@...gnar.org>
To: "Rafael J. Wysocki" <rjw@...k.pl>
Cc: Linux PM list <linux-pm@...r.kernel.org>,
ACPI Devel Mailing List <linux-acpi@...r.kernel.org>,
Alan Stern <stern@...land.harvard.edu>,
Huang Ying <ying.huang@...el.com>,
Sarah Sharp <sarah.a.sharp@...ux.intel.com>,
Lan Tianyu <tianyu.lan@...el.com>,
Aaron Lu <aaron.lu@...el.com>, Jean Pihet <j-pihet@...com>,
linux-pci@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
mark gross <markgross@...gnar.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/7] PM / QoS: Introduce PM QoS device flags support
On Mon, Oct 08, 2012 at 10:07:10AM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>
> Modify the device PM QoS core code to support PM QoS flags requests.
>
> First, add a new field of type struct pm_qos_flags called "flags"
> to struct dev_pm_qos for representing the list of PM QoS flags
> requests for the given device. Accordingly, add a new "type" field
> to struct dev_pm_qos_request (along with an enum for representing
> request types) and a new member called "flr" to its data union for
> representig flags requests.
>
> Second, modify dev_pm_qos_add_request(), dev_pm_qos_update_request(),
> the internal routine apply_constraint() used by them and their
> existing callers to cover flags requests as well as latency
> requests. In particular, dev_pm_qos_add_request() gets a new
> argument called "type" for specifying the type of a request to be
> added.
>
> Finally, introduce two routines, __dev_pm_qos_flags() and
> dev_pm_qos_flags(), allowing their callers to check which PM QoS
> flags have been requested for the given device (the caller is
> supposed to pass the mask of flags to check as the routine's
> second argument and examine its return value for the result).
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Reviewed-by: Jean Pihet <j-pihet@...com>
> ---
> Documentation/power/pm_qos_interface.txt | 2
> drivers/base/power/qos.c | 124 ++++++++++++++++++++++++-------
> drivers/mtd/nand/sh_flctl.c | 4 -
> include/linux/pm_qos.h | 26 ++++++
> 4 files changed, 127 insertions(+), 29 deletions(-)
>
> Index: linux/drivers/base/power/qos.c
> ===================================================================
> --- linux.orig/drivers/base/power/qos.c
> +++ linux/drivers/base/power/qos.c
> @@ -48,6 +48,50 @@ static DEFINE_MUTEX(dev_pm_qos_mtx);
> static BLOCKING_NOTIFIER_HEAD(dev_pm_notifiers);
>
> /**
> + * __dev_pm_qos_flags - Check PM QoS flags for a given device.
> + * @dev: Device to check the PM QoS flags for.
> + * @mask: Flags to check against.
> + *
> + * This routine must be called with dev->power.lock held.
> + */
> +enum pm_qos_flags_status __dev_pm_qos_flags(struct device *dev, s32 mask)
> +{
> + struct dev_pm_qos *qos = dev->power.qos;
> + struct pm_qos_flags *pqf;
> + s32 val;
> +
> + if (!qos)
> + return PM_QOS_FLAGS_UNDEFINED;
> +
> + pqf = &qos->flags;
> + if (list_empty(&pqf->list))
> + return PM_QOS_FLAGS_UNDEFINED;
> +
> + val = pqf->effective_flags & mask;
> + if (val)
> + return (val == mask) ? PM_QOS_FLAGS_ALL : PM_QOS_FLAGS_SOME;
> +
> + return PM_QOS_FLAGS_NONE;
> +}
> +
> +/**
> + * dev_pm_qos_flags - Check PM QoS flags for a given device (locked).
> + * @dev: Device to check the PM QoS flags for.
> + * @mask: Flags to check against.
> + */
> +enum pm_qos_flags_status dev_pm_qos_flags(struct device *dev, s32 mask)
> +{
> + unsigned long irqflags;
> + enum pm_qos_flags_status ret;
> +
> + spin_lock_irqsave(&dev->power.lock, irqflags);
> + ret = __dev_pm_qos_flags(dev, mask);
> + spin_unlock_irqrestore(&dev->power.lock, irqflags);
> +
> + return ret;
> +}
> +
> +/**
> * __dev_pm_qos_read_value - Get PM QoS constraint for a given device.
> * @dev: Device to get the PM QoS constraint value for.
> *
> @@ -74,30 +118,39 @@ s32 dev_pm_qos_read_value(struct device
> return ret;
> }
>
> -/*
> - * apply_constraint
> - * @req: constraint request to apply
> - * @action: action to perform add/update/remove, of type enum pm_qos_req_action
> - * @value: defines the qos request
> +/**
> + * apply_constraint - Add/modify/remove device PM QoS request.
> + * @req: Constraint request to apply
> + * @action: Action to perform (add/update/remove).
> + * @value: Value to assign to the QoS request.
> *
> * Internal function to update the constraints list using the PM QoS core
> * code and if needed call the per-device and the global notification
> * callbacks
> */
> static int apply_constraint(struct dev_pm_qos_request *req,
> - enum pm_qos_req_action action, int value)
> + enum pm_qos_req_action action, s32 value)
> {
> - int ret, curr_value;
> -
> - ret = pm_qos_update_target(&req->dev->power.qos->latency,
> - &req->data.pnode, action, value);
> + struct dev_pm_qos *qos = req->dev->power.qos;
> + int ret;
>
> - if (ret) {
> - /* Call the global callbacks if needed */
> - curr_value = pm_qos_read_value(&req->dev->power.qos->latency);
> - blocking_notifier_call_chain(&dev_pm_notifiers,
> - (unsigned long)curr_value,
> - req);
> + switch(req->type) {
> + case DEV_PM_QOS_LATENCY:
> + ret = pm_qos_update_target(&qos->latency, &req->data.pnode,
> + action, value);
> + if (ret) {
> + value = pm_qos_read_value(&qos->latency);
> + blocking_notifier_call_chain(&dev_pm_notifiers,
> + (unsigned long)value,
> + req);
> + }
> + break;
> + case DEV_PM_QOS_FLAGS:
> + ret = pm_qos_update_flags(&qos->flags, &req->data.flr,
> + action, value);
> + break;
> + default:
> + ret = -EINVAL;
> }
>
> return ret;
> @@ -134,6 +187,8 @@ static int dev_pm_qos_constraints_alloca
> c->type = PM_QOS_MIN;
> c->notifiers = n;
>
> + INIT_LIST_HEAD(&qos->flags.list);
> +
> spin_lock_irq(&dev->power.lock);
> dev->power.qos = qos;
> spin_unlock_irq(&dev->power.lock);
> @@ -207,6 +262,7 @@ void dev_pm_qos_constraints_destroy(stru
> * dev_pm_qos_add_request - inserts new qos request into the list
> * @dev: target device for the constraint
> * @req: pointer to a preallocated handle
> + * @type: type of the request
> * @value: defines the qos request
> *
> * This function inserts a new entry in the device constraints list of
> @@ -222,7 +278,7 @@ void dev_pm_qos_constraints_destroy(stru
> * from the system.
> */
> int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
> - s32 value)
> + enum dev_pm_qos_req_type type, s32 value)
> {
> int ret = 0;
>
> @@ -253,8 +309,10 @@ int dev_pm_qos_add_request(struct device
> }
> }
>
> - if (!ret)
> + if (!ret) {
> + req->type = type;
> ret = apply_constraint(req, PM_QOS_ADD_REQ, value);
> + }
>
> out:
> mutex_unlock(&dev_pm_qos_mtx);
> @@ -281,6 +339,7 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_add_request
> int dev_pm_qos_update_request(struct dev_pm_qos_request *req,
> s32 new_value)
> {
> + s32 curr_value;
> int ret = 0;
>
> if (!req) /*guard against callers passing in null */
> @@ -292,15 +351,27 @@ int dev_pm_qos_update_request(struct dev
>
> mutex_lock(&dev_pm_qos_mtx);
>
> - if (req->dev->power.qos) {
> - if (new_value != req->data.pnode.prio)
> - ret = apply_constraint(req, PM_QOS_UPDATE_REQ,
> - new_value);
> - } else {
> - /* Return if the device has been removed */
> + if (!req->dev->power.qos) {
> ret = -ENODEV;
> + goto out;
> }
>
> + switch(req->type) {
> + case DEV_PM_QOS_LATENCY:
> + curr_value = req->data.pnode.prio;
> + break;
> + case DEV_PM_QOS_FLAGS:
> + curr_value = req->data.flr.flags;
> + break;
> + default:
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + if (curr_value != new_value)
> + ret = apply_constraint(req, PM_QOS_UPDATE_REQ, new_value);
> +
> + out:
> mutex_unlock(&dev_pm_qos_mtx);
> return ret;
> }
> @@ -451,7 +522,8 @@ int dev_pm_qos_add_ancestor_request(stru
> ancestor = ancestor->parent;
>
> if (ancestor)
> - error = dev_pm_qos_add_request(ancestor, req, value);
> + error = dev_pm_qos_add_request(ancestor, req,
> + DEV_PM_QOS_LATENCY, value);
>
> if (error)
> req->dev = NULL;
> @@ -487,7 +559,7 @@ int dev_pm_qos_expose_latency_limit(stru
> if (!req)
> return -ENOMEM;
>
> - ret = dev_pm_qos_add_request(dev, req, value);
> + ret = dev_pm_qos_add_request(dev, req, DEV_PM_QOS_LATENCY, value);
> if (ret < 0)
> return ret;
>
> Index: linux/include/linux/pm_qos.h
> ===================================================================
> --- linux.orig/include/linux/pm_qos.h
> +++ linux/include/linux/pm_qos.h
> @@ -20,6 +20,13 @@ enum {
> PM_QOS_NUM_CLASSES,
> };
>
> +enum pm_qos_flags_status {
> + PM_QOS_FLAGS_UNDEFINED = -1,
> + PM_QOS_FLAGS_NONE,
> + PM_QOS_FLAGS_SOME,
> + PM_QOS_FLAGS_ALL,
> +};
> +
> #define PM_QOS_DEFAULT_VALUE -1
>
> #define PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC)
> @@ -38,9 +45,16 @@ struct pm_qos_flags_request {
> s32 flags; /* Do not change to 64 bit */
> };
>
> +enum dev_pm_qos_req_type {
> + DEV_PM_QOS_LATENCY = 1,
> + DEV_PM_QOS_FLAGS,
> +};
> +
> struct dev_pm_qos_request {
> + enum dev_pm_qos_req_type type;
> union {
> struct plist_node pnode;
> + struct pm_qos_flags_request flr;
> } data;
> struct device *dev;
> };
> @@ -71,6 +85,7 @@ struct pm_qos_flags {
>
> struct dev_pm_qos {
> struct pm_qos_constraints latency;
> + struct pm_qos_flags flags;
> };
>
> /* Action requested to pm_qos_update_target */
> @@ -105,10 +120,12 @@ int pm_qos_request_active(struct pm_qos_
> s32 pm_qos_read_value(struct pm_qos_constraints *c);
>
> #ifdef CONFIG_PM
> +enum pm_qos_flags_status __dev_pm_qos_flags(struct device *dev, s32 mask);
> +enum pm_qos_flags_status dev_pm_qos_flags(struct device *dev, s32 mask);
> s32 __dev_pm_qos_read_value(struct device *dev);
> s32 dev_pm_qos_read_value(struct device *dev);
> int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
> - s32 value);
> + enum dev_pm_qos_req_type type, s32 value);
> int dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value);
> int dev_pm_qos_remove_request(struct dev_pm_qos_request *req);
> int dev_pm_qos_add_notifier(struct device *dev,
> @@ -122,12 +139,19 @@ void dev_pm_qos_constraints_destroy(stru
> int dev_pm_qos_add_ancestor_request(struct device *dev,
> struct dev_pm_qos_request *req, s32 value);
> #else
> +static inline enum pm_qos_flags_status __dev_pm_qos_flags(struct device *dev,
> + s32 mask)
> + { return PM_QOS_FLAGS_UNDEFINED; }
> +static inline enum pm_qos_flags_status dev_pm_qos_flags(struct device *dev,
> + s32 mask)
> + { return PM_QOS_FLAGS_UNDEFINED; }
> static inline s32 __dev_pm_qos_read_value(struct device *dev)
> { return 0; }
> static inline s32 dev_pm_qos_read_value(struct device *dev)
> { return 0; }
> static inline int dev_pm_qos_add_request(struct device *dev,
> struct dev_pm_qos_request *req,
> + enum dev_pm_qos_req_type type,
> s32 value)
> { return 0; }
> static inline int dev_pm_qos_update_request(struct dev_pm_qos_request *req,
> Index: linux/drivers/mtd/nand/sh_flctl.c
> ===================================================================
> --- linux.orig/drivers/mtd/nand/sh_flctl.c
> +++ linux/drivers/mtd/nand/sh_flctl.c
> @@ -710,7 +710,9 @@ static void flctl_select_chip(struct mtd
>
> if (!flctl->qos_request) {
> ret = dev_pm_qos_add_request(&flctl->pdev->dev,
> - &flctl->pm_qos, 100);
> + &flctl->pm_qos,
> + DEV_PM_QOS_LATENCY,
> + 100);
> if (ret < 0)
> dev_err(&flctl->pdev->dev,
> "PM QoS request failed: %d\n", ret);
> Index: linux/Documentation/power/pm_qos_interface.txt
> ===================================================================
> --- linux.orig/Documentation/power/pm_qos_interface.txt
> +++ linux/Documentation/power/pm_qos_interface.txt
> @@ -99,7 +99,7 @@ reading the aggregated value does not re
>
> From kernel mode the use of this interface is the following:
>
> -int dev_pm_qos_add_request(device, handle, value):
> +int dev_pm_qos_add_request(device, handle, type, value):
> Will insert an element into the list for that identified device with the
> target value. Upon change to this list the new target is recomputed and any
> registered notifiers are called only if the target value is now different.
>
Reviewed-by: mark gross <markgross@...gnar.org>
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