From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Peter 'p2' De Schrijver" Subject: Re: [PATCH 0/1] OMAP3 PM Add C0 state Date: Tue, 24 Feb 2009 12:27:09 +0200 Message-ID: <20090224102709.GA4569@codecarver.research.nokia.com> References: <1234974118-27446-1-git-send-email-peter.de-schrijver@nokia.com> <87ljrx9fl3.fsf@deeprootsystems.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from smtp.nokia.com ([192.100.122.230]:40857 "EHLO mgw-mx03.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753159AbZBXK2y (ORCPT ); Tue, 24 Feb 2009 05:28:54 -0500 Content-Disposition: inline In-Reply-To: <87ljrx9fl3.fsf@deeprootsystems.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: ext Kevin Hilman Cc: "linux-omap@vger.kernel.org" On Mon, Feb 23, 2009 at 07:24:24PM +0100, ext Kevin Hilman wrote: > "Peter 'p2' De Schrijver" writes: > > > This patch introduces a new C state C0 which keeps both core and mpu > > powerdomains in ON state. This gives us low latency at a cost of higher > > power consumption. > > > > I don't like the name 'C0' for an idle-state. In ACPI terms, C0 is an > active state, not an idle state. I know this is not an ACPI system, > but since we're using ACPI names, we should be consistent. > > Is there a real benefit to having an additional state here? Shouldn't > we just make these changes or C1? > C1 has a too high wakeup latency (10s of us) for some cases, but C0 (which has a 3us wakeup latency) keeps core on which implies little powersavings. So I think we need both. Cheers, Peter. -- goa is a state of mind