linux-kernel - Re: [PATCH] PM: Do not create wakeup sysfs files for devices that cannot wake up (v2)

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Message-Id: <201102061953.17433.rjw@sisk.pl>
Date:	Sun, 6 Feb 2011 19:53:17 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Alan Stern <stern@...land.harvard.edu>, Greg KH <greg@...ah.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Linux PM mailing list <linux-pm@...ts.linux-foundation.org>,
	Minchan Kim <minchan.kim@...il.com>
Subject: Re: [PATCH] PM: Do not create wakeup sysfs files for devices that cannot wake up (v2)

On Sunday, February 06, 2011, Alan Stern wrote:
> On Sun, 6 Feb 2011, Rafael J. Wysocki wrote:
> 
> > Hi,
> > 
> > Below is the next version of the patch changing the PM core to only create
> > wakeup sysfs files for devices that are wakeup-capable.  It contains a change
> > in drivers/usb/core/hub.c that should avoid the problem described in the thread
> > at https://lkml.org/lkml/2011/2/5/108 , but I'm not 100% it's the right
> > approach.  Please have a look.
> 
> Yes, that's right -- in fact, it's exactly the same as what I was going
> to do.  Of course, it should be separated out into a separate patch, to
> be applied before the other wakeup changes.

OK, I'll split it out.

Greg, any objections to me putting the change below into the suspend tree as
a separate commit:

Index: linux-2.6/drivers/usb/core/hub.c
===================================================================
--- linux-2.6.orig/drivers/usb/core/hub.c
+++ linux-2.6/drivers/usb/core/hub.c
@@ -1465,6 +1465,7 @@ void usb_set_device_state(struct usb_dev
                enum usb_device_state new_state)
 {
        unsigned long flags;
+       int wakeup = -1;
 
        spin_lock_irqsave(&device_state_lock, flags);
        if (udev->state == USB_STATE_NOTATTACHED)
@@ -1479,11 +1480,10 @@ void usb_set_device_state(struct usb_dev
                                        || new_state == USB_STATE_SUSPENDED)
                                ;       /* No change to wakeup settings */
                        else if (new_state == USB_STATE_CONFIGURED)
-                               device_set_wakeup_capable(&udev->dev,
-                                       (udev->actconfig->desc.bmAttributes
-                                        & USB_CONFIG_ATT_WAKEUP));
+                               wakeup = udev->actconfig->desc.bmAttributes
+                                        & USB_CONFIG_ATT_WAKEUP;
                        else
-                               device_set_wakeup_capable(&udev->dev, 0);
+                               wakeup = 0;
                }
                if (udev->state == USB_STATE_SUSPENDED &&
                        new_state != USB_STATE_SUSPENDED)
@@ -1495,6 +1495,8 @@ void usb_set_device_state(struct usb_dev
        } else
                recursively_mark_NOTATTACHED(udev);
        spin_unlock_irqrestore(&device_state_lock, flags);
+       if (wakeup >= 0)
+               device_set_wakeup_capable(&udev->dev, wakeup);
 }
 EXPORT_SYMBOL_GPL(usb_set_device_state);

Thanks,
Rafael
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