From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nigel Cunningham Subject: Re: [linux-pm] [patch/rft 2.6.17-rc2] swsusp resume must not device_suspend() Date: Fri, 28 Apr 2006 06:35:55 +1000 Message-ID: <200604280636.03606.ncunningham@cyclades.com> References: <20060427080826.GB2376@ucw.cz> <20060427165536.GA3113@linux.intel.com> <200604271221.47160.david-b@pacbell.net> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart1801530.bG3V3x8fEY"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200604271221.47160.david-b@pacbell.net> Sender: linux-usb-devel-admin@lists.sourceforge.net Errors-To: linux-usb-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: David Brownell Cc: Patrick Mochel , Alan Stern , Pavel Machek , Andrew Morton , linux-pm@lists.osdl.org, linux-usb-devel@lists.sourceforge.net List-Id: linux-pm@vger.kernel.org --nextPart1801530.bG3V3x8fEY Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Hi. On Friday 28 April 2006 05:21, David Brownell wrote: > On Thursday 27 April 2006 9:55 am, Patrick Mochel wrote: > > On Thu, Apr 27, 2006 at 10:34:16AM -0400, Alan Stern wrote: > > > During swsusp the system is > > > supposed to be completely off, with no suspend power available. Hence > > > all the power sessions are guaranteed to be interrupted, and the boot > > > kernel doesn't have to worry about destroying any of them. > > > > Not necessarily. x86 hardware implementations of suspend-to-disk retain > > some power during suspend. Not many (if any) devices will retain contex= t, > > but the system is definitely not completely "off". > > As a rule swsusp (or firmware suspend-to-disk) power off everything except > what's needed to power up the motherboard ... or to provide "5 AM wakeup" > type events using a battery-backed realtime clock. Maintaining VBUS power > sessions from USB host controllers is one of those "theoretically allowed, > but never observed in the wild" cases. > > Right, not "completely" off ... but certainly nowhere as close to "on" as > would be true of suspend-to-RAM. And regardless, the problem in $SUBJECT > is when Linux trashes the state which the limited "on" is there to > maintain. This isn't necessarily true either. Suspend2 has supported writing the imag= e,=20 then suspending to ram for a year or two. uswsusp has just gained the same= =20 functionality. In this state, if you don't pull the plug/drain the battery,= =20 you never actually power down. Having said that, this might be a different= =20 kettle of fish though, because there's no boot kernel in that case. For=20 Suspend2 (and uswsusp, I assume), it's more akin to backing out of the cycl= e=20 at the last possible moment before powering down. Regards, Nigel --nextPart1801530.bG3V3x8fEY Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQBEUSszN0y+n1M3mo0RAhPIAKCO9wK53RV1k//5Q0u6E1IUPJSWxQCfTRjx dkoHsPDjSixB08EfXiZ82p8= =DWX3 -----END PGP SIGNATURE----- --nextPart1801530.bG3V3x8fEY-- ------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel