From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751958AbdBULOg (ORCPT ); Tue, 21 Feb 2017 06:14:36 -0500 Received: from foss.arm.com ([217.140.101.70]:58902 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751826AbdBULO3 (ORCPT ); Tue, 21 Feb 2017 06:14:29 -0500 Subject: Re: [PATCH/RFC 3/6] drivers: firmware: psci: Implement shallow suspend mode To: Pavel Machek , Geert Uytterhoeven References: <1487622809-25127-1-git-send-email-geert+renesas@glider.be> <1487622809-25127-4-git-send-email-geert+renesas@glider.be> <20170221110712.GB5021@amd> Cc: Sudeep Holla , Lorenzo Pieralisi , Mark Rutland , Lina Iyer , John Stultz , Thomas Gleixner , "Rafael J . Wysocki" , Len Brown , Rob Herring , Magnus Damm , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-renesas-soc@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org From: Sudeep Holla Organization: ARM Message-ID: Date: Tue, 21 Feb 2017 11:14:16 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <20170221110712.GB5021@amd> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21/02/17 11:07, Pavel Machek wrote: > Hi! > >> Enable support for "shallow" suspend mode, also known as "Standby" or >> "Power-On Suspend". >> >> As secondary CPU cores are taken offline, "shallow" suspend mode saves >> slightly more power than "s2idle", but less than "deep" suspend mode. >> However, unlike "deep" suspend mode, "shallow" suspend mode can be used >> regardless of the presence of support for PSCI_SYSTEM_SUSPEND, which is >> an optional API in PSCI v1.0. > > If system supports "shallow" suspend, why does not PSCI implement it? > Yes it can, and IIUC it already does on this platform with CPU_SUSPEND. All it now needs is just to use existing "freeze" suspend mode in Linux. > In the past, I was told PSCI will not turn into ACPI-like mess, and > that we'll be able to fix PSCI and will not have to work around its > problems in kernel :-(. Can you be more elaborate on the mess you see on this Renesas platform. For me, it looks like this patch is attempting to *re-implement* the existing "suspend-to-idle" functionality. So IMO, this patch set is creating unnecessary mess giving an illusion that PSCI specification is broken. -- Regards, Sudeep