linux-kernel - [PATCH] 2.6.18-rc6-mm2 - usb_resume_both()

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Message-ID: <Pine.LNX.4.64.0609190314470.9787@twin.jikos.cz>
Date:	Tue, 19 Sep 2006 03:17:03 +0200 (CEST)
From:	Jiri Kosina <jikos@...os.cz>
To:	Andrew Morton <akpm@...l.org>
cc:	linux-kernel@...r.kernel.org, linux-usb-devel@...ts.sourceforge.net
Subject: [PATCH] 2.6.18-rc6-mm2 - usb_resume_both() - fix suspend/resume

With 2.6.18-rc6-mm2 it is possible on my IBM T42p to do suspend/resume 
cycle only once. The second time, suspend fails with

	usb_hcd_pci_suspend(): ehci_pci_suspend+0x0/0xd0 [ehci_hcd]() returns -22
	pci_device_suspend(): usb_hcd_pci_suspend+0x0/0x280() returns -22
	suspend_device(): pci_device_suspend+0x0/0x70() returns -22

or, when ehci is unloaded, uhci fails in a similar way:

	usb_hcd_pci_suspend(): uhci_suspend+0x0/0xf0 [uhci_hcd]() returns -16
	pci_device_suspend(): usb_hcd_pci_suspend+0x0/0x1c0() returns -16
	suspend_device(): pci_device_suspend+0x0/0x70() returns -16

(by the way this looks to me like a mess, that the user could be presented 
with either -EINVAL or -EBUSY, in case of the same error, depending on the 
device driver which reports it. I will probably submit a consolidating 
patch later this evening).

After some time I figured out that usb_resume_both() is not resuming 
devices properly - it calls resume_device() only for those devices which 
are USB_STATE_SUSPENDED (in which case we want to propagate the resume 
recursively up the device tree), but other cases (most notably 
USB_STATE_CONFIGURED) stay unhadled.

This patch fixes my issue, now the suspend/resume can be done arbitrary 
number of times without any error.

Signed-off-by: Jiri Kosina <jikos@...os.cz>

--- linux-2.6.18-rc6-mm2.orig/drivers/usb/core/driver.c	2006-09-14 16:20:48.000000000 +0200
+++ linux-2.6.18-rc6-mm2/drivers/usb/core/driver.c	2006-09-19 03:03:12.000000000 +0200
@@ -1083,6 +1083,8 @@ int usb_resume_both(struct usb_device *u
 			status = resume_device(udev);
 		if (parent)
 			mutex_unlock(&parent->pm_mutex);
+	} else {
+		status = resume_device(udev);
 	}

 	/* Now the parent won't suspend until we are finished */

-- 
Jiri Kosina
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