On Tue, 5 Feb 2008, David Brownell wrote:

> The reason to try powering off the ports is that, well, the system is
> shutting down.  Why waste (potentially battery) power?  Whatever runs
> next can turn it back on if it wants.  And if PPS isn't set, then trying
> to clear the per-port power-enabled flag is supposed to be a NOP.

There's another reason for powering off the ports during shutdown -- 
without it, some mahcines would reboot instead of shutting down!  
Arguably this may have been an ACPI or BIOS bug rather than EHCI, but 
nevertheless, the fix worked.  See

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=8903795a5275e0366acf961190c57074ad27f9bb

and

http://bugzilla.kernel.org/show_bug.cgi?id=7828

Alan Stern

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