Re: [PATCH V4 4/9] PM / QOS: Add DEV_PM_QOS_PERFORMANCE request

From: Ulf Hansson
Date: Wed Apr 19 2017 - 10:08:02 EST

On 20 March 2017 at 10:32, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
> Some platforms have the capability to configure the performance state of
> their Power Domains. The performance levels are identified by positive
> integer values, a lower value represents lower performance state. The
> power domain driver should be able to retrieve all information required
> to configure the performance state of the power domain, with the help of
> the performance constraint's target value.
>
> This patch adds a new QOS request type: DEV_PM_QOS_PERFORMANCE to
> support runtime performance constraints for the devices. Also allow
> notifiers to be registered against it, which will be used by frameworks
> like genpd.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> ---
> Documentation/power/pm_qos_interface.txt | 2 +-
> drivers/base/power/qos.c | 21 +++++++++++++++++++++
> include/linux/pm_qos.h | 10 ++++++++++
> 3 files changed, 32 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/power/pm_qos_interface.txt b/Documentation/power/pm_qos_interface.txt
> index 21d2d48f87a2..4b7decdebf98 100644
> --- a/Documentation/power/pm_qos_interface.txt
> +++ b/Documentation/power/pm_qos_interface.txt
> @@ -168,7 +168,7 @@ The per-device PM QoS framework has a per-device notification tree.
> int dev_pm_qos_add_notifier(device, notifier):
> Adds a notification callback function for the device.
> The callback is called when the aggregated value of the device constraints list
> -is changed (for resume latency device PM QoS only).
> +is changed (for resume latency and performance device PM QoS only).

/s/ only/

>
> int dev_pm_qos_remove_notifier(device, notifier):
> Removes the notification callback function for the device.
> diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
> index 654d8a12c2e7..084d26960dae 100644
> --- a/drivers/base/power/qos.c
> +++ b/drivers/base/power/qos.c
> @@ -150,6 +150,10 @@ static int apply_constraint(struct dev_pm_qos_request *req,
> req->dev->power.set_latency_tolerance(req->dev, value);
> }
> break;
> + case DEV_PM_QOS_PERFORMANCE:
> + ret = pm_qos_update_target(&qos->performance, &req->data.pnode,
> + action, value);
> + break;
> case DEV_PM_QOS_FLAGS:
> ret = pm_qos_update_flags(&qos->flags, &req->data.flr,
> action, value);
> @@ -194,6 +198,14 @@ static int dev_pm_qos_constraints_allocate(struct device *dev)
> c->no_constraint_value = PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT;
> c->type = PM_QOS_MIN;
>
> + c = &qos->performance;
> + plist_head_init(&c->list);
> + c->target_value = PM_QOS_PERFORMANCE_DEFAULT_VALUE;
> + c->default_value = PM_QOS_PERFORMANCE_DEFAULT_VALUE;
> + c->no_constraint_value = PM_QOS_PERFORMANCE_DEFAULT_VALUE;
> + c->type = PM_QOS_MAX;
> + c->notifiers = &qos->notifiers;
> +
> INIT_LIST_HEAD(&qos->flags.list);
>
> spin_lock_irq(&dev->power.lock);
> @@ -252,6 +264,11 @@ 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->performance;
> + 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);
> @@ -362,6 +379,7 @@ 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:
> + case DEV_PM_QOS_PERFORMANCE:
> curr_value = req->data.pnode.prio;
> break;
> case DEV_PM_QOS_FLAGS:
> @@ -571,6 +589,9 @@ static void __dev_pm_qos_drop_user_request(struct device *dev,
> req = dev->power.qos->flags_req;
> dev->power.qos->flags_req = NULL;
> break;
> + case DEV_PM_QOS_PERFORMANCE:
> + dev_err(dev, "Invalid user request (performance)\n");
> + return;

Isn't it possible to drop a performance request?

> }
> __dev_pm_qos_remove_request(req);
> kfree(req);
> diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
> index bcae6abb3f21..0f5135d55406 100644
> --- a/include/linux/pm_qos.h
> +++ b/include/linux/pm_qos.h
> @@ -36,6 +36,7 @@ enum pm_qos_flags_status {
> #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_PERFORMANCE_DEFAULT_VALUE 0
> #define PM_QOS_LATENCY_ANY ((s32)(~(__u32)0 >> 1))
>
> #define PM_QOS_FLAG_NO_POWER_OFF (1 << 0)
> @@ -55,6 +56,7 @@ 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_PERFORMANCE,
> DEV_PM_QOS_FLAGS,
> };
>
> @@ -96,9 +98,11 @@ struct pm_qos_flags {
> struct dev_pm_qos {
> struct pm_qos_constraints resume_latency;
> struct pm_qos_constraints latency_tolerance;
> + struct pm_qos_constraints performance;
> 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 *performance_req;

I didn't find performance_req being used at all...

> struct dev_pm_qos_request *flags_req;
> struct blocking_notifier_head notifiers; /* common for all constraints */
> };
> @@ -121,6 +125,12 @@ static inline bool dev_pm_qos_notifier_is_resume_latency(struct device *dev,
> return &dev->power.qos->resume_latency == c;
> }
>
> +static inline bool dev_pm_qos_notifier_is_performance(struct device *dev,

Similar comment as for patch 3, perhaps remove "notifier" from the
name of the function.

> + struct pm_qos_constraints *c)
> +{
> + return &dev->power.qos->performance == c;
> +}
> +
> int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
> enum pm_qos_req_action action, int value);
> bool pm_qos_update_flags(struct pm_qos_flags *pqf,
> --
> 2.12.0.432.g71c3a4f4ba37
>

Kind regards
Uffe