linux-kernel - Re: [PATCH] USB: improve ehci_watchdog's side effect in CPU power management

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Message-ID: <Pine.LNX.4.44L0.0811211354350.2376-100000@iolanthe.rowland.org>
Date:	Fri, 21 Nov 2008 13:56:32 -0500 (EST)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Yi Yang <yi.y.yang@...el.com>
cc:	David Brownell <david-b@...bell.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"gregkh@...e.de" <gregkh@...e.de>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Subject: Re: [PATCH] USB: improve ehci_watchdog's side effect in CPU power
 management

On Fri, 21 Nov 2008, Yi Yang wrote:

> But on Asus EeePC, i saw another periodical timer usb_hcd_poll_rh_status
> which fires every 256 milisecond, is this also doing with some
> hardware's quirk?

That timer is associated mostly with UHCI controllers.  It is not 
because of a hardware quirk.  If the controller is suspended (for 
example, because no devices are attached to it) then the timer should 
stop.

Alan Stern

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