[PATCH V2] PM / Domains: Sync runtime PM status with genpd after probe

[PATCH V2] PM / Domains: Sync runtime PM status with genpd after probe

[Ulf Hansson]

From: Russell King <rmk+kernel@arm.linux.org.uk>

Buses which currently supports attaching devices to their PM domains,
will invoke the dev_pm_domain_attach() API from their ->probe()
callbacks. During the attach procedure, genpd power up the PM domain.

In those scenarios where the bus/driver don't need to access its device
during probe, it may leave it in runtime PM suspended state since
that's also the default state. In that way, no notifications through
the runtime PM callbacks will reach the PM domain during probe.

For genpd, the consequence from the above scenario means the PM domain
will remain powered. Therefore, implement the struct dev_pm_domain's
->sync() callback, which is invoked from driver core after the
bus/driver has probed the device. It allows genpd to power off the PM
domain if it's unused.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
[Ulf: Updated patch according to updates in driver core]
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---

Changes in v2:
	- I picked up Russell's earlier patch [1] and updated it to fit the
	changes [2] proposed to be done to the driver core.

	[1]: [PATCH 3/9] pm: domains: sync runtime PM status with PM domains
	after probe

	[2]: [PATCH v3] driver core / PM: Add PM domain callbacks for device
	setup/cleanup
	http://www.spinics.net/lists/arm-kernel/msg407394.html

---
 drivers/base/power/domain.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 45937f8..295ff71 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -2130,6 +2130,17 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off)
 	genpd_queue_power_off_work(pd);
 }
 
+static void genpd_dev_pm_sync(struct device *dev)
+{
+	struct generic_pm_domain *pd;
+
+	pd = dev_to_genpd(dev);
+	if (IS_ERR(pd))
+		return;
+
+	genpd_queue_power_off_work(pd);
+}
+
 /**
  * genpd_dev_pm_attach - Attach a device to its PM domain using DT.
  * @dev: Device to attach.
@@ -2196,6 +2207,7 @@ int genpd_dev_pm_attach(struct device *dev)
 	}
 
 	dev->pm_domain->detach = genpd_dev_pm_detach;
+	dev->pm_domain->sync = genpd_dev_pm_sync;
 	pm_genpd_poweron(pd);
 
 	return 0;
-- 
1.9.1

Re: [PATCH V2] PM / Domains: Sync runtime PM status with genpd after probe

[Kevin Hilman]

Ulf Hansson <ulf.hansson@linaro.org> writes:

> From: Russell King <rmk+kernel@arm.linux.org.uk>
>
> Buses which currently supports attaching devices to their PM domains,
> will invoke the dev_pm_domain_attach() API from their ->probe()
> callbacks. During the attach procedure, genpd power up the PM domain.
>
> In those scenarios where the bus/driver don't need to access its device
> during probe, it may leave it in runtime PM suspended state since
> that's also the default state. In that way, no notifications through
> the runtime PM callbacks will reach the PM domain during probe.
>
> For genpd, the consequence from the above scenario means the PM domain
> will remain powered. Therefore, implement the struct dev_pm_domain's
> ->sync() callback, which is invoked from driver core after the
> bus/driver has probed the device. It allows genpd to power off the PM
> domain if it's unused.
>
> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
> [Ulf: Updated patch according to updates in driver core]
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
>
> Changes in v2:
> 	- I picked up Russell's earlier patch [1] and updated it to fit the
> 	changes [2] proposed to be done to the driver core.
>
> 	[1]: [PATCH 3/9] pm: domains: sync runtime PM status with PM domains
> 	after probe
>
> 	[2]: [PATCH v3] driver core / PM: Add PM domain callbacks for device
> 	setup/cleanup
> 	http://www.spinics.net/lists/arm-kernel/msg407394.html

Ah, I hadn't seen this when I reviewed Rafael's v3 and suggested
Russell's patch be reworked.  This is just what I had in mind.

Acked-by: Kevin Hilman <khilman@linaro.org>