From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754034Ab1IJFxN (ORCPT ); Sat, 10 Sep 2011 01:53:13 -0400 Received: from na3sys009aog125.obsmtp.com ([74.125.149.153]:39346 "EHLO na3sys009aog125.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751190Ab1IJFxM (ORCPT ); Sat, 10 Sep 2011 01:53:12 -0400 Message-ID: <4E6AFB3E.3020902@ti.com> Date: Sat, 10 Sep 2011 11:23:02 +0530 From: Santosh User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.18) Gecko/20110617 Thunderbird/3.1.11 MIME-Version: 1.0 To: Kevin Hilman CC: linux-arm-kernel@lists.infradead.org, linux@arm.linux.org.uk, linux-kernel@vger.kernel.org, rjw@sisk.pl, ccross@android.com Subject: Re: [PATCH v2 0/5] CPU PM notifiers References: <1315060755-4613-1-git-send-email-santosh.shilimkar@ti.com> <87ty8ly4rp.fsf@ti.com> In-Reply-To: <87ty8ly4rp.fsf@ti.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday 09 September 2011 11:30 PM, Kevin Hilman wrote: > Santosh Shilimkar writes: > > [...] > >> This patch set tries to address concerns with platform pm code >> calling into the driver for every block in the Cortex A9s >> during idle, hotplug, and suspend. The first patch adds cpu pm >> notifiers that can be called by platform code, the second uses >> the notifier to save and restore the GIC state, and the third >> saves the VFP state. >> >> The notifiers are used for two types of events, CPU PM events and >> CPU cluster PM events. CPU PM events are used to save and restore >> per-cpu context when a single CPU is preparing to enter or has >> just exited a low power state. For example, the VFP saves the >> last thread context, and the GIC saves banked CPU registers. >> >> CPU cluster events are used after all the CPUs in a power domain >> have been prepared for the low power state. The GIC uses these >> events to save global register state. > > Stepping back from my earlier objections, I think I had a fundamental > misunderstanding about what these notifiers should be used for. > > The current assumptions/goals seem to be > > 1) used only for devices in the same power domain as the CPU (cluster) > 2) use only for one specific power state of the CPU (cluster): off. > > For awhile now, we've been discussing how to better coordinate CPU PM > transitions (CPUidle) with non-CPU PM transitions (runtime PM) for > devices that are tightly coupled to the CPU, but not necessarily in the > same powerdomain. > > I was assuming (and hoping) that CPU PM notifiers could be used to do > that, but the more I think about it, I don't think we can achieve the > current CPU PM goals and the coordination with runtime PM with this > series. > > I think it's more likely that we'll need to do some work with Rafael's > new PM domains to make that work correctly. > > So, I'll retract my objections to this series, and feel free to add > > Reviewed-by: Kevin Hilman > Will add. Thanks for the review Kevin. Regards Santosh Regards From mboxrd@z Thu Jan 1 00:00:00 1970 From: santosh.shilimkar@ti.com (Santosh) Date: Sat, 10 Sep 2011 11:23:02 +0530 Subject: [PATCH v2 0/5] CPU PM notifiers In-Reply-To: <87ty8ly4rp.fsf@ti.com> References: <1315060755-4613-1-git-send-email-santosh.shilimkar@ti.com> <87ty8ly4rp.fsf@ti.com> Message-ID: <4E6AFB3E.3020902@ti.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Friday 09 September 2011 11:30 PM, Kevin Hilman wrote: > Santosh Shilimkar writes: > > [...] > >> This patch set tries to address concerns with platform pm code >> calling into the driver for every block in the Cortex A9s >> during idle, hotplug, and suspend. The first patch adds cpu pm >> notifiers that can be called by platform code, the second uses >> the notifier to save and restore the GIC state, and the third >> saves the VFP state. >> >> The notifiers are used for two types of events, CPU PM events and >> CPU cluster PM events. CPU PM events are used to save and restore >> per-cpu context when a single CPU is preparing to enter or has >> just exited a low power state. For example, the VFP saves the >> last thread context, and the GIC saves banked CPU registers. >> >> CPU cluster events are used after all the CPUs in a power domain >> have been prepared for the low power state. The GIC uses these >> events to save global register state. > > Stepping back from my earlier objections, I think I had a fundamental > misunderstanding about what these notifiers should be used for. > > The current assumptions/goals seem to be > > 1) used only for devices in the same power domain as the CPU (cluster) > 2) use only for one specific power state of the CPU (cluster): off. > > For awhile now, we've been discussing how to better coordinate CPU PM > transitions (CPUidle) with non-CPU PM transitions (runtime PM) for > devices that are tightly coupled to the CPU, but not necessarily in the > same powerdomain. > > I was assuming (and hoping) that CPU PM notifiers could be used to do > that, but the more I think about it, I don't think we can achieve the > current CPU PM goals and the coordination with runtime PM with this > series. > > I think it's more likely that we'll need to do some work with Rafael's > new PM domains to make that work correctly. > > So, I'll retract my objections to this series, and feel free to add > > Reviewed-by: Kevin Hilman > Will add. Thanks for the review Kevin. Regards Santosh Regards