From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Brown Subject: Re: [linux-pm] [PATCH 02/11] PM: extend PM QoS with per-device wake-up constraints Date: Tue, 23 Aug 2011 10:21:56 +0100 Message-ID: <20110823092155.GJ9232@opensource.wolfsonmicro.com> References: <20110820062543.GA5011@opensource.wolfsonmicro.com> <201108202114.37502.rjw@sisk.pl> <20110821082509.GA10380@opensource.wolfsonmicro.com> <201108212005.53898.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from opensource.wolfsonmicro.com ([80.75.67.52]:39285 "EHLO opensource2.wolfsonmicro.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754646Ab1HWJV6 (ORCPT ); Tue, 23 Aug 2011 05:21:58 -0400 Content-Disposition: inline In-Reply-To: <201108212005.53898.rjw@sisk.pl> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "Rafael J. Wysocki" Cc: Alan Stern , Linux PM mailing list , linux-omap@vger.kernel.org, Jean Pihet , markgross@thegnar.org On Sun, Aug 21, 2011 at 08:05:53PM +0200, Rafael J. Wysocki wrote: > On Sunday, August 21, 2011, Mark Brown wrote: > > I don't understand why the driver would need to know what situation it's > > in. I'd been working on the basis that the idea was that the driver > > said what the constraints it has are and then some code with a more > > system wide view would make the actual decisions for things outside the > > driver domian. > That's correct, but in order to figure out a "sensible default" > the driver generally would need to know what the expectations with > respect to it are. Otherwise it can very well generate a random > number and use that. Right, but I'd expect that should be something that the driver can generally do based on knowledge of what it needs to deliver to its users. It doesn't need to be tunable to that - for example, input devices will have a reasonable idea of the response time needed to deliver interactive performance. If it's really got no idea then hopefully not providng any constraints will do something sensible.