Re: [RFC][PATCH 0/7] PM: Asynchronous suspend and resume (updated)

On Tuesday 18 August 2009, Rafael J. Wysocki wrote:

quoted

On Tuesday 18 August 2009, Zhang Rui wrote:

quoted

On Mon, 2009-08-17 at 08:15 +0800, Rafael J. Wysocki wrote:

quoted

On Wednesday 12 August 2009, Rafael J. Wysocki wrote:

quoted

Hi,

The following patches introduce a mechanism allowing us to execute device
drivers' suspend and resume callbacks asynchronously during system sleep
transitions, such as suspend to RAM.  The idea is explained in the [1/1] patch
message.

Changes:

* Added [1/7] that fixes kerneldoc comments in drivers/base/power/main.c
  (this is a 2.6.32 candidate).

* Added [2/7] adding a framework for representing PM link (idea described
  in the patch message).

* [3/7] is the async resume patch (idea described in the patch message).

* [4/7] is the async suspend patch.

* [5/7] - [7/7] set async_suspend for devices in a few selected subsystems.

The patches have been tested on HP nx6325.

I tried this patch set and it does work. :)
But unfortunately it doesn't save too much time.

I still think that the child device should inherit its parent's
async_suspend flag to do the asynchronous resume more efficiently.

or at least we should provide such an interface
in drivers/base/power/common.c, so that device can tell the device core
to inherit this flag if there is no off-tree dependency.

Well, I'd prefer to identify all of the off-tree dependencies that have to be
taken into account and handle all devices asynchronously.

Anyway, I have tested the appended patch on top of [1/7]-[7/7] and my test box
appears to work fine with it, although it doesn't work in the "async for all"
case.

I guess the next step will be to see which devices are not handled
asynchronously with the patch below and try to figure out which of them
break(s) things.

Thanks,
Rafael

---
 drivers/base/power/common.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Index: linux-2.6/drivers/base/power/common.c
===================================================================

--- linux-2.6.orig/drivers/base/power/common.c
+++ linux-2.6/drivers/base/power/common.c

@@ -32,7 +32,11 @@ void device_pm_add(struct device *dev)
 	pr_debug("PM: Adding info for %s:%s\n",
 		 dev->bus ? dev->bus->name : "No Bus",
 		 kobject_name(&dev->kobj));
-	pm_link_add(dev, dev->parent);
+	if (dev->parent) {
+		pm_link_add(dev, dev->parent);
+		if (dev->parent->power.async_suspend)
+			dev->power.async_suspend = true;
+	}