From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932586Ab1EQXGR (ORCPT ); Tue, 17 May 2011 19:06:17 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:33496 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932562Ab1EQXGQ (ORCPT ); Tue, 17 May 2011 19:06:16 -0400 From: "Rafael J. Wysocki" To: Raffaele Recalcati Subject: Re: [linux-pm] pm loss development Date: Wed, 18 May 2011 01:06:56 +0200 User-Agent: KMail/1.13.6 (Linux/2.6.39-rc7+; KDE/4.6.0; x86_64; ; ) Cc: Oliver Neukum , linux-pm@lists.linux-foundation.org, davinci-linux-open-source@linux.davincidsp.com, linux-kernel@vger.kernel.org References: <1305220265-9020-1-git-send-email-lamiaposta71@gmail.com> <201105142053.34920.oliver@neukum.org> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <201105180106.57147.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Saturday, May 14, 2011, Raffaele Recalcati wrote: > On Sat, May 14, 2011 at 8:53 PM, Oliver Neukum wrote: > > Am Donnerstag, 12. Mai 2011, 21:27:44 schrieb Rafael J. Wysocki: > >> On Thursday, May 12, 2011, Raffaele Recalcati wrote: > >> > What happen normally in runtime pm implementation is that every devices > >> > are switched off and are enabled only when needed. > >> > In our case instead we have a completely functional embedded system and, > >> > when an asyncrhonous event appear, we have only some tens milliseconds > >> > before the actual power failure takes place. > >> > This patchset add a support in order to switch off not vital part of the system, > >> > in order to allow the board to survive longer. > >> > This allow the possibility to save important data. > >> > >> OK, so first, who decides what parts of the system are vital and what aren't? > > > > If you know that power is failing in a few miliseconds, only stuff that can lead to data > > corruption is vital. In that timeframe you can't even flush buffers. > > Remember that if you switch off some peripherals this timeframe > becomes longer, so maybe you have enough time to sync some storage > devices. However, switching off peripherals _also_ takes time. So, it may be more useful to take care of the stuff leading to data corruption along with the switching off peripherals. Thanks, Rafael