From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: trenn@suse.de
Cc: "Kaburlasos, Nikos" <nikos.kaburlasos@intel.com>,
linux-acpi@vger.kernel.org,
Alan Stern <stern@rowland.harvard.edu>
Subject: Re: USB suspend/resume in linux
Date: Fri, 13 Oct 2006 13:28:40 +0200 [thread overview]
Message-ID: <200610131328.40857.rjw@sisk.pl> (raw)
In-Reply-To: <1160728740.2096.243.camel@queen.suse.de>
On Friday, 13 October 2006 10:39, Thomas Renninger wrote:
> On Thu, 2006-10-12 at 22:54 -0700, Kaburlasos, Nikos wrote:
> > Does anyone know whether the linux USB drivers support the suspend
> > feature on idle USB ports (i.e. the port has been idle for sometime and
> > so the driver transitions it in to a low-power 'suspend' state) while
> > the system is active and in S0 state? As far as I know, Windows don't
> > support that, I was wondering if linux does.
> >
> > Please note, I have no background on linux or in OS programming (I am a
> > hardware guy), so please be gentle with the level of technical detail in
> > your response :-)
>
> AFAIK linux is not doing that.
> Therefore the ohci (also uhci?) drivers need to poll the ports quite
> often even there is no device attached. This makes C-states less
> efficient (what should save more power than the suspended USB ports). I
> thought Windows is doing that, I at least heard Mac OS is doing it like
> that, but I don't know for sure.
> The proper solution to avoid polling should be to suspend idle ports,
> stop polling and wait for some kind of resume/attach event, but AFAIK
> nobody really works on that. Would be nice if someone gives this a
> try...
Alan Stern has been working on USB autosuspend for quite some time
and there are some patches in -mm and in the recent mainline, AFAICT.
Greetings,
Rafael
--
You never change things by fighting the existing reality.
R. Buckminster Fuller
next prev parent reply other threads:[~2006-10-13 11:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-13 5:54 USB suspend/resume in linux Kaburlasos, Nikos
2006-10-13 8:39 ` Thomas Renninger
2006-10-13 11:28 ` Rafael J. Wysocki [this message]
2006-10-13 14:19 ` Alan Stern
-- strict thread matches above, loose matches on Subject: below --
2006-10-13 14:37 Kaburlasos, Nikos
2006-10-13 15:13 ` Alan Stern
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