linux-kernel - Re: [GIT PULL] PM updates for 2.6.33

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Date:	Sun, 6 Dec 2009 15:36:40 -0500 (EST)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Arjan van de Ven <arjan@...radead.org>
cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	LKML <linux-kernel@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>
Subject: Re: [GIT PULL] PM updates for 2.6.33

On Sun, 6 Dec 2009, Arjan van de Ven wrote:

> btw I instrumented both the suspend and resume, and made graphs out of
> it for my laptop (modern laptop with Intel cpu/wifi/graphics of course).
> 
> http://www.fenrus.org/graphs/suspend.svg
> http://www.fenrus.org/graphs/resume.svg
> 
> (also attached for convenience)
> 
> the resume clearly shows that all this talking about PCI stuff is
> completely without practical merit.. it's the USB stuff where the time
> is spent.

Arjan, can you try testing the USB timings again with the patch below 
(for vanilla 2.6.32)?

Fair warning: I just composed this and haven't tried it out myself.

Thanks,

Alan Stern



Index: 2.6.32/drivers/usb/core/driver.c
===================================================================
--- 2.6.32.orig/drivers/usb/core/driver.c
+++ 2.6.32/drivers/usb/core/driver.c
@@ -1313,8 +1313,9 @@ static int usb_resume_both(struct usb_de
 			 * then we're stuck. */
 			status = usb_resume_device(udev, msg);
 		}
-	} else if (udev->reset_resume)
+	} else {
 		status = usb_resume_device(udev, msg);
+	}
 
 	if (status == 0 && udev->actconfig) {
 		for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
Index: 2.6.32/drivers/usb/core/hub.c
===================================================================
--- 2.6.32.orig/drivers/usb/core/hub.c
+++ 2.6.32/drivers/usb/core/hub.c
@@ -1674,7 +1674,7 @@ static int usb_configure_device_otg(stru
 		 * (Includes HNP test device.)
 		 */
 		if (udev->bus->b_hnp_enable || udev->bus->is_b_host) {
-			err = usb_port_suspend(udev, PMSG_SUSPEND);
+			err = usb_port_suspend(udev, PMSG_AUTO_SUSPEND);
 			if (err < 0)
 				dev_dbg(&udev->dev, "HNP fail, %d\n", err);
 		}
@@ -2060,6 +2060,7 @@ static int check_port_resume_type(struct
 /*
  * usb_port_suspend - suspend a usb device's upstream port
  * @udev: device that's no longer in active use, not a root hub
+ * @msg: Power Management message describing this state transition
  * Context: must be able to sleep; device not locked; pm locks held
  *
  * Suspends a USB device that isn't in active use, conserving power.
@@ -2107,7 +2108,7 @@ int usb_port_suspend(struct usb_device *
 {
 	struct usb_hub	*hub = hdev_to_hub(udev->parent);
 	int		port1 = udev->portnum;
-	int		status;
+	int		status = 0;
 
 	// dev_dbg(hub->intfdev, "suspend port %d\n", port1);
 
@@ -2128,6 +2129,13 @@ int usb_port_suspend(struct usb_device *
 					status);
 	}
 
+	/* For system sleep transitions we don't actually need to suspend
+	 * the port.  The device will suspend itself when the entire bus
+	 * is suspended.
+	 */
+	if (!(msg.event & (PM_EVENT_USER | PM_EVENT_REMOTE | PM_EVENT_AUTO)))
+		return status;
+
 	/* see 7.1.7.6 */
 	status = set_port_feature(hub->hdev, port1, USB_PORT_FEAT_SUSPEND);
 	if (status) {
@@ -2231,6 +2239,7 @@ static int finish_port_resume(struct usb
 /*
  * usb_port_resume - re-activate a suspended usb device's upstream port
  * @udev: device to re-activate, not a root hub
+ * @msg: Power Management message describing this state transition
  * Context: must be able to sleep; device not locked; pm locks held
  *
  * This will re-activate the suspended device, increasing power usage

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