Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760526Ab0FKUsS (ORCPT ); Fri, 11 Jun 2010 16:48:18 -0400 Received: from netrider.rowland.org ([192.131.102.5]:33234 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753307Ab0FKUsR (ORCPT ); Fri, 11 Jun 2010 16:48:17 -0400 Date: Fri, 11 Jun 2010 16:48:15 -0400 (EDT) From: Alan Stern X-X-Sender: stern@netrider.rowland.org To: James Bottomley cc: David Brownell , , Peter Zijlstra , Neil Brown , Brian Swetland , Felipe Balbi , LKML , Florian Mickler , Peter Zijlstra , Thomas Gleixner , Linux PM , Linux OMAP Mailing List , Linus Torvalds , Ingo Molnar , Alan Cox Subject: Re: [linux-pm] suspend blockers & Android integration In-Reply-To: <1276268539.2862.92.camel@mulgrave.site> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1505 Lines: 40 On Fri, 11 Jun 2010, Mark Brown wrote: > On Fri, Jun 11, 2010 at 10:46:27AM -0400, Alan Stern wrote: > > On Fri, 11 Jun 2010, James Bottomley wrote: > > > > The one thing that does look difficult is that these power constraints > > > are device (and sometimes SoC) specific. Expressing them in a generic > > > way for the cpu govenors to make sense of might be hard. > > > Doesn't the clock framework already handle this sort of thing? > > The clock framework is implemented independantly for each CPU. That's not an impediment, since drivers' requirements regarding which clocks remain running in which power states are necessarily platform-dependent also. On Fri, 11 Jun 2010, James Bottomley wrote: > Well, there are two elements to "this sort of thing": > > 1. Allow a driver to request that a given clock not be turned off. > 2. Make the cpuidle governors aware of a pending "don't turn off X > clock source" so they can keep the system in a state where the > clock doesn't get powered down. > > As far as I can tell from the code, neither currently exists at the > moment. Well then, can (or should) the clock framework interact with the pm-qos subsystem so that drivers don't have to worry about it? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/