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[PATCH v5 0/2]

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  [PATCH v5 0/2]  Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-29 14:40 +0200
    [PATCH v5 2/2] USB / PM: Allow USB devices to remain runtime-suspended when sleeping Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-29 14:40 +0200

#1235024 — [PATCH v5 0/2]

Hi,

this is v5 of an attempt to make it easier for devices to remain in
runtime PM when the system goes to sleep, mainly to reduce the time
spent resuming devices.

For this, we interpret the absence of all PM callback implementations as
it being safe to do direct_complete, so their ancestors aren't prevented
from remaining runtime-suspended.

Additionally, the prepare() callback of USB devices will return 1 if
runtime PM is enabled and the current wakeup settings are correct.

With these changes, a uvcvideo device (for example) stays in runtime
suspend when the system goes to sleep and is left in that state when the
system resumes, not delaying it unnecessarily.

Thanks,

Tomeu

Changes in v5:
- Check for all dev_pm_ops instances associated to a device, updating a
  no_pm_callbacks flag at the times when that could change.

Tomeu Vizoso (2):
  PM / sleep: Go direct_complete if driver has no callbacks
  USB / PM: Allow USB devices to remain runtime-suspended when sleeping

 drivers/base/dd.c           |  3 ++
 drivers/base/power/domain.c |  5 ++++
 drivers/base/power/main.c   | 69 ++++++++++++++++++++++++++++++++-------------
 drivers/base/power/power.h  |  2 ++
 drivers/usb/core/port.c     |  6 ++++
 drivers/usb/core/usb.c      | 11 +++++++-
 include/linux/pm.h          |  1 +
 7 files changed, 77 insertions(+), 20 deletions(-)

-- 
2.4.3

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#1235027 — [PATCH v5 2/2] USB / PM: Allow USB devices to remain runtime-suspended when sleeping

Have dev_pm_ops.prepare return 1 for USB devices and ports so that USB
devices can remain runtime-suspended when the system goes to a sleep
state, if their wakeup state is correct and they have runtime PM enabled.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---


 drivers/usb/core/port.c |  6 ++++++
 drivers/usb/core/usb.c  | 11 ++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
index 210618319f10..f49707d73b5a 100644
--- a/drivers/usb/core/port.c
+++ b/drivers/usb/core/port.c
@@ -168,12 +168,18 @@ static int usb_port_runtime_suspend(struct device *dev)
 
 	return retval;
 }
+
+static int usb_port_prepare(struct device *dev)
+{
+	return 1;
+}
 #endif
 
 static const struct dev_pm_ops usb_port_pm_ops = {
 #ifdef CONFIG_PM
 	.runtime_suspend =	usb_port_runtime_suspend,
 	.runtime_resume =	usb_port_runtime_resume,
+	.prepare =		usb_port_prepare,
 #endif
 };
 
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 8d5b2f4113cd..cf4dde11db1c 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -316,7 +316,16 @@ static int usb_dev_uevent(struct device *dev, struct kobj_uevent_env *env)
 
 static int usb_dev_prepare(struct device *dev)
 {
-	return 0;		/* Implement eventually? */
+	struct usb_device *udev = to_usb_device(dev);
+
+	if (!pm_runtime_enabled(dev))
+		return 0;
+
+	/* Return 0 if the current wakeup setting is wrong, otherwise 1 */
+	if (udev->do_remote_wakeup != device_may_wakeup(dev))
+		return 0;
+
+	return 1;
 }
 
 static void usb_dev_complete(struct device *dev)
-- 
2.4.3

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