From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from wf-out-1314.google.com (wf-out-1314.google.com [209.85.200.171]) by ozlabs.org (Postfix) with ESMTP id 6D4F0DDD04 for ; Wed, 25 Mar 2009 21:42:43 +1100 (EST) Received: by wf-out-1314.google.com with SMTP id 24so3590348wfg.15 for ; Wed, 25 Mar 2009 03:42:41 -0700 (PDT) MIME-Version: 1.0 Sender: pku.leo@gmail.com In-Reply-To: <20090323165402.GC25217@ld0162-tx32.am.freescale.net> References: <49C3AB35.4080700@freescale.com> <3A45394FD742FA419B760BB8D398F9ED2FA48E@zch01exm26.fsl.freescale.net> <20090323165402.GC25217@ld0162-tx32.am.freescale.net> Date: Wed, 25 Mar 2009 18:42:41 +0800 Message-ID: <2a27d3730903250342qc7c98abt95534372af174703@mail.gmail.com> Subject: Re: suspend-to-mem on the mpc8349e-mitx-gp? From: Li Yang To: Scott Wood , Pavel Machek Content-Type: text/plain; charset=UTF-8 Cc: linuxppc-dev@ozlabs.org, Soohyung Cho List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Mar 24, 2009 at 12:54 AM, Scott Wood wrot= e: > On Sun, Mar 22, 2009 at 10:45:23PM -0700, Li Yang-R58472 wrote: >> > I don't think so, in this case. =C2=A0The user is not asking for >> > "sleep" or deep sleep"; they are asking for a power state >> > that meets the definition of "standby" (which sleep does) or >> > which meets the definition of "mem" >> > (which both sleep and deep sleep do). =C2=A0When the user asks for >> > "mem", we provide the lowest power mode that qualifies. >> >> In my understanding, "mem" which is suspend-to-ram means all CPU states >> and registers are kept in memory and the CPU is completely off during >> suspension. =C2=A0I don't think the sleep mode of 8349 qualifies, does i= t? > > Is there a difference visible to software or to the user (other than not > achieving power savings that the board does not support)? =C2=A0It seems > simpler for userspace to just specify the "heaviest" sleep state it wants > deal with (though some feedback to an administrator of what actually > happens would be nice). I agree that it's handy to have a "sleep" state in kernel to automatically enter the "heaviest" sleep state supported. However it is also very simple for user space script or application to check the available states first and then enter explicitly the "heaviest" sleep state. Pavel, what's the preferred way for current PM sub-system? - Leo > > And if we want to be really pedantic, neither sleep nor deep sleep meet > the definitions for either "standby" or "mem", because they specify > acceptable latency ranges in seconds, and (in the absence of a disk) we > are much faster than that (it doesn't say "up to 1-2 seconds"). :-) > > Are there any existing suspend drivers that suppord standby but not mem? > I see omap1 as a counterexample that treats them both the same. > > -Scott