Re: [patch]Re: autosuspend for HID devices, take #2

Am Freitag, 25. Mai 2007 04:20 schrieb Alan Stern:
> On Thu, 24 May 2007, Greg KH wrote:
> 
> > On Wed, May 23, 2007 at 06:25:36PM +0200, Oliver Neukum wrote:
> > > Am Mittwoch, 23. Mai 2007 17:42 schrieb Alan Stern:
> > > > On Wed, 23 May 2007, Oliver Neukum wrote:
> > > > 
> > > > > That gives me an idea.
> > > > > Resumption of a device has to be done in task context. So if I allocate
> > > > > a private freezable work queue for HID resumption, the freezer would
> > > > > guard against illicit resumptions, wouldn't it?
> > > > 
> > > > You can use the ksuspend_usb_wq workqueue.  It already exists, is 
> > > > freezable, and is used for suspending and resuming USB devices.
> > > 
> > > This adds a clean accessor for the USB core pm workqueue.
> > 
> > But what code is using it?  I don't want to add an api call if no one
> > uses it...

I can assure you that any input driver that has some output (HID,
PID, etc) will use this.

> In fact there's a potential user in hcd.c:usb_hcd_resume_root_hub().  
> If there's to be an accessor, that routine should use it.

Done.
 
> Oliver, you should be careful about what happens when CONFIG_PM is off.  
> Under those conditions the workqueue is not created.

Done

	Regards
		Oliver
Signed-off-by: Oliver Neukum <[email protected]>
-- 

--- a/include/linux/usb.h	2007-05-23 10:20:35.000000000 +0200
+++ b/include/linux/usb.h	2007-05-23 18:08:31.000000000 +0200
@@ -1343,6 +1343,8 @@ extern int usb_set_interface(struct usb_
 /* this request isn't really synchronous, but it belongs with the others */
 extern int usb_driver_set_configuration(struct usb_device *udev, int config);
 
+extern void usb_schedule_power_work(struct work_struct *work);
+
 /*
  * timeouts, in milliseconds, used for sending/receiving control messages
  * they typically complete within a few frames (msec) after they're issued
--- a/drivers/usb/core/message.c	2007-05-22 14:50:32.000000000 +0200
+++ b/drivers/usb/core/message.c	2007-05-25 10:54:03.000000000 +0200
@@ -1648,6 +1648,24 @@ int usb_driver_set_configuration(struct 
 }
 EXPORT_SYMBOL_GPL(usb_driver_set_configuration);
 
+/**
+ * usb_schedule_power_work - allow drivers to execute work in the context of the pm thread
+ * @work: work to be executed
+ *
+ * This allows work to be scheduled which is to be executed under the
+ * same conditions pm's internal works are performed, namely to be
+ * frozen when they are frozen
+ */
+
+void usb_schedule_power_work(struct work_struct *work)
+{
+#ifdef	CONFIG_PM
+	queue_work(ksuspend_usb_wq, work);
+#endif
+}
+
+EXPORT_SYMBOL(usb_schedule_power_work);
+
 // synchronous request completion model
 EXPORT_SYMBOL(usb_control_msg);
 EXPORT_SYMBOL(usb_bulk_msg);
--- a/drivers/usb/core/hcd.c	2007-05-22 14:50:32.000000000 +0200
+++ b/drivers/usb/core/hcd.c	2007-05-25 10:53:56.000000000 +0200
@@ -1326,7 +1326,7 @@ void usb_hcd_resume_root_hub (struct usb
 
 	spin_lock_irqsave (&hcd_root_hub_lock, flags);
 	if (hcd->rh_registered)
-		queue_work(ksuspend_usb_wq, &hcd->wakeup_work);
+		usb_schedule_power_work(&hcd->wakeup_work);
 	spin_unlock_irqrestore (&hcd_root_hub_lock, flags);
 }
 EXPORT_SYMBOL_GPL(usb_hcd_resume_root_hub);

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