Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752783AbcJDLdo (ORCPT ); Tue, 4 Oct 2016 07:33:44 -0400 Received: from mail-pa0-f68.google.com ([209.85.220.68]:34020 "EHLO mail-pa0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751125AbcJDLdm (ORCPT ); Tue, 4 Oct 2016 07:33:42 -0400 Subject: Re: [PATCH 2/2] powernv: Pass PSSCR value and mask to power9_idle_stop To: Michael Ellerman , "Gautham R. Shenoy" , Stewart Smith , "skiboot@lists.ozlabs.org" References: <21e080ffa52f432b40750028a624aee1baebbaf7.1475130107.git.ego@linux.vnet.ibm.com> <87int84d6w.fsf@concordia.ellerman.id.au> Cc: Benjamin Herrenschmidt , Paul Mackerras , "Rafael J. Wysocki" , Daniel Lezcano , Michael Neuling , Vaidyanathan Srinivasan , "Shreyas B. Prabhu" , Shilpasri G Bhat , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org From: Balbir Singh Message-ID: <0e7ad8ff-8c44-86bc-f560-258bc7b29a32@gmail.com> Date: Tue, 4 Oct 2016 22:33:27 +1100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: <87int84d6w.fsf@concordia.ellerman.id.au> 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 Content-Length: 1676 Lines: 41 On 04/10/16 21:32, Michael Ellerman wrote: > "Gautham R. Shenoy" writes: > >> From: "Gautham R. Shenoy" >> >> The power9_idle_stop method currently takes only the requested stop >> level as a parameter and picks up the rest of the PSSCR bits from a >> hand-coded macro. This is not a very flexible design, especially when >> the firmware has the capability to communicate the psscr value and the >> mask associated with a particular stop state via device tree. >> >> This patch modifies the power9_idle_stop API to take as parameters the >> PSSCR value and the PSSCR mask corresponding to the stop state that >> needs to be set. These PSSCR value and mask are respectively obtained >> by parsing the "ibm,cpu-idle-state-psscr" and >> "ibm,cpu-idle-state-psscr-mask" fields from the device tree. >> >> In addition to this, the patch adds support for handling stop states >> for which ESL and EC bits in the PSSCR are zero. As per the >> architecture, a wakeup from these stop states resumes execution from >> the subsequent instruction as opposed to waking up at the System >> Vector. > > That looks good. > >> This patch depends on the following skiboot patch that exports the >> PSSCR values and the mask for all the stop states: >> https://lists.ozlabs.org/pipermail/skiboot/2016-September/004869.html > > But we can't depend on a skiboot patch. The kernel has to cope with > running on an old skiboot. Hi, Michael I think with an older skiboot the flags don't get exported and the new cpuidle (stop state) does not get discovered. I don't think there is any breakage. Gautham am I missing something? Balbir Singh.