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From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Thu, 24 Nov 2005 21:50:22 +0100
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Cc: Andrew Morton <akpm@osdl.org>, Greg KH <greg@kroah.com>,
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	Alan Stern <stern@rowland.harvard.edu>
Subject: Re: [PATCH] Fix USB suspend/resume crasher
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On Thursday, 24 of November 2005 02:23, Benjamin Herrenschmidt wrote:
> 
> > Unfortunately with this patch the EHCI controller in my box (Asus L5D,
> > x86-64 kernel) does not resume from suspend.  Appended is the relevant
> > snippet from the serial console log (EHCI is the only device using IRQ #5).
> 
> Hrm... let me see... You are getting an interrupt for EHCI after it has
> been resumed, so it should work.
> 
>  /me double-checks the patch
> 
> > ehci_hcd 0000:00:02.2: lost power, restarting
> 
> Hrm... I can't find that line in the code...
> 
>  /me rechecks with david's other patches
> 
> Ah ... I see it. There might have been some screwup between david's
> patch and mine.
> 
> Make sure that 
> 
>        set_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
> 
> Is still done before anything else in ehci_pci_resume().

Well, it's there (actually the problem occurs in vanilla 2.6.15-rc2-mm1 that
contains the patch).  Do you mean it should go before the

if (readl(&ehci->regs->configured_flag) != FLAG_CF)
		goto restart;

thing?

> It may be worth following it with a memory barrier actually... just in case
> (due to the absence of locks in that area).

wmb()?

Rafael