From: Thomas Renninger <trenn@suse.de>
To: "Kaburlasos, Nikos" <nikos.kaburlasos@intel.com>
Cc: linux-acpi@vger.kernel.org
Subject: Re: USB suspend/resume in linux
Date: Fri, 13 Oct 2006 10:39:00 +0200 [thread overview]
Message-ID: <1160728740.2096.243.camel@queen.suse.de> (raw)
In-Reply-To: <0FB24CC078F78248B19595A43F00E01FD92D24@fmsmsx413.amr.corp.intel.com>
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...
Thomas
next prev parent reply other threads:[~2006-10-13 8:28 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 [this message]
2006-10-13 11:28 ` Rafael J. Wysocki
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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