Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752905AbaBEQ2X (ORCPT ); Wed, 5 Feb 2014 11:28:23 -0500 Received: from avon.wwwdotorg.org ([70.85.31.133]:50003 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751786AbaBEQ2W (ORCPT ); Wed, 5 Feb 2014 11:28:22 -0500 Message-ID: <52F266A2.1030503@wwwdotorg.org> Date: Wed, 05 Feb 2014 09:28:18 -0700 From: Stephen Warren User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Alexandre Courbot CC: Alexandre Courbot , Thierry Reding , Russell King , Olof Johansson , "linux-arm-kernel@lists.infradead.org" , "linux-tegra@vger.kernel.org" , Linux Kernel Mailing List Subject: Re: [PATCH 5/5] ARM: tegra: cpuidle: use firmware call for power down References: <1390299016-14105-1-git-send-email-acourbot@nvidia.com> <1390299016-14105-6-git-send-email-acourbot@nvidia.com> <52E02DCC.1000404@wwwdotorg.org> In-Reply-To: X-Enigmail-Version: 1.5.2 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/23/2014 12:39 AM, Alexandre Courbot wrote: > On Thu, Jan 23, 2014 at 5:45 AM, Stephen Warren wrote: >> On 01/21/2014 03:10 AM, Alexandre Courbot wrote: >>> Invoke the do_idle() firmware call before suspending a CPU so that the >>> underlying firmware (if any) can take necessary action. >> >>> diff --git a/arch/arm/mach-tegra/cpuidle-tegra114.c b/arch/arm/mach-tegra/cpuidle-tegra114.c >> >>> @@ -45,6 +46,8 @@ static int tegra114_idle_power_down(struct cpuidle_device *dev, >>> >>> clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu); >>> >>> + call_firmware_op(do_idle); >>> + >>> cpu_suspend(0, tegra30_sleep_cpu_secondary_finish); >>> >>> clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu); >> >> Don't you need to have the kernel also *not* do something when entering >> idle; doesn't the FW op replace some of the register writes that the >> kernel would otherwise be doing? > > It seems like the operation is actually to inform the firmware that we > are going to suspend the CPU. Downstream kernel also uses it that way. > But you are right in that we should expect do_idle() to actually > perform the suspend operation. Maybe a prepare_idle() operation should > be added to the firmware interface for this purpose? That sounds like a reasonable change. Is it easy to plumb in? -- 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/