From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Subject: Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8) Date: Thu, 27 May 2010 18:31:18 +0100 Message-ID: <20100527173118.GE2468@srcf.ucam.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from cavan.codon.org.uk ([93.93.128.6]:36814 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755073Ab0E0Rbc (ORCPT ); Thu, 27 May 2010 13:31:32 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Thomas Gleixner Cc: Alan Stern , Peter Zijlstra , Paul@smtp1.linux-foundation.org, LKML , Florian Mickler , felipe.balbi@nokia.com, Linux OMAP Mailing List , Linux PM , Alan Cox On Thu, May 27, 2010 at 07:24:02PM +0200, Thomas Gleixner wrote: > Oh no. They paper over a short coming. If there is a pending event, > the kernel knows that. It just does not make use of this > information. Blockers just paper over this by sprinkling > do_not_suspend() calls all over the place. What a sensible solution. Even if we could use suspend-via-deep-idle-state on PCs, we still need to be able to enter suspend while the system isn't idle. There's two ways to do that: 1) Force the system to be idle. Doing this race-free is difficult. 2) Enter suspend even though the system isn't idle. Since we can't rely on the scheduler, we need drivers to know whether userspace has consumed all wakeup events before allowing the transition to occur. Doing so requires either in-kernel suspend blockers or something that's almost identical. -- Matthew Garrett | mjg59@srcf.ucam.org