Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030312AbWILSRP (ORCPT ); Tue, 12 Sep 2006 14:17:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030330AbWILSRP (ORCPT ); Tue, 12 Sep 2006 14:17:15 -0400 Received: from alnrmhc11.comcast.net ([206.18.177.51]:49365 "EHLO alnrmhc11.comcast.net") by vger.kernel.org with ESMTP id S1030312AbWILSRN (ORCPT ); Tue, 12 Sep 2006 14:17:13 -0400 Subject: Re: ACPI: Idle Processor PM Improvements From: Jim Gettys Reply-To: jg@laptop.org To: Pavel Machek Cc: Jordan Crouse , "Brown, Len" , Linux Kernel ML , Dominik Brodowski , ACPI ML , Adam Belay , "Pallipadi, Venkatesh" , Arjan van de Ven , devel@laptop.org, Bjorn Helgaas In-Reply-To: <20060912092100.GC19482@elf.ucw.cz> References: <20060830194317.GA9116@srcf.ucam.org> <200608311713.21618.bjorn.helgaas@hp.com> <1157070616.7974.232.camel@localhost.localdomain> <20060904130933.GC6279@ucw.cz> <1157466710.6011.262.camel@localhost.localdomain> <20060906103725.GA4987@atrey.karlin.mff.cuni.cz> <20060906145849.GE2623@cosmic.amd.com> <20060912092100.GC19482@elf.ucw.cz> Content-Type: text/plain Organization: OLPC Date: Tue, 12 Sep 2006 14:14:30 -0400 Message-Id: <1158084871.28991.489.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1753 Lines: 45 On Tue, 2006-09-12 at 11:21 +0200, Pavel Machek wrote: > Ok, so what is needed is message to X "we are suspending", and X needs > to respond "okay, I'm ready, no need for console switch". This presumes an external agent to X controlling the fast suspend/resume, with messages having to flow to and from X, and to and from the kernel, with the kernel in the middle. Another simpler option is X itself just telling the kernel to suspend without console switch, as the handoff of the display to the DCON chip has to be done with X and with an interrupt signaling completion of the handoff. This would be triggered by an inactivity timeout in the X server. I'm not sure which is best right now: generality vs. simplicity. We just got samples of hardware to do some prototyping on in the last two weeks. (see wiki.laptop.org for photographs of our screen and the DCON in action). > > Alternatively, hack kernel to take control from X without actually > switching consoles. That should be possible even with current > interface. This would require saving/restoring all graphics state in the kernel (and X already has that state internally). Feasible, but seems like duplication of effort. I haven't checked if there are any write-only registers in the Geode (though, thankfully, this kind of brain damage is rarer than it once was). This then begs interesting kernel/X synchronization issues, of course. - Jim > Pavel -- Jim Gettys One Laptop Per Child - 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/