Re: hid powersave by autosuspend #2

On Tue, 6 Feb 2007, Oliver Neukum wrote:

> Hi,
> 
> this fixes the issue with output in the hid driver. I can now get keyboards
> to sleep. It is still not perfect, but an important step. Comments?
> 
> 	Regards
> 		Oliver
> 
> PS: against vanilla 2.6.20

I'd really prefer to see something like the patch below added instead of 
your idle timer.  (Note: not even compile-tested!)

With this infrastructure in place, all you have to do is

	set_bit(USB_DF_DEVICE_BUSY, &hid_to_usb_dev(hid)->dflags);

whenever an event occurs.  No messing around with extra timers.

Alan Stern



Index: usb-2.6/drivers/usb/core/usb.c
===================================================================
--- usb-2.6.orig/drivers/usb/core/usb.c
+++ usb-2.6/drivers/usb/core/usb.c
@@ -209,8 +209,13 @@ static void usb_autosuspend_work(struct 
 		container_of(work, struct usb_device, autosuspend.work);
 
 	usb_pm_lock(udev);
-	udev->auto_pm = 1;
-	usb_suspend_both(udev, PMSG_SUSPEND);
+	if (test_and_clear_bit(USB_DF_DEVICE_BUSY, &udev->dflags))
+		queue_delayed_work(ksuspend_usb_wq, &udev->autosuspend,
+				USB_AUTOSUSPEND_DELAY);
+	else {
+		udev->auto_pm = 1;
+		usb_suspend_both(udev, PMSG_SUSPEND);
+	}
 	usb_pm_unlock(udev);
 }
 
Index: usb-2.6/include/linux/usb.h
===================================================================
--- usb-2.6.orig/include/linux/usb.h
+++ usb-2.6/include/linux/usb.h
@@ -389,6 +389,9 @@ struct usb_device {
 
 	int pm_usage_cnt;		/* usage counter for autosuspend */
 	u32 quirks;			/* quirks of the whole device */
+	unsigned long dflags;		/* device-wide atomic bitflags */
+#define USB_DF_DEVICE_BUSY	0
+
 #ifdef CONFIG_PM
 	struct delayed_work autosuspend; /* for delayed autosuspends */
 	struct mutex pm_mutex;		/* protects PM operations */


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