From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E0991C43381 for ; Wed, 27 Mar 2019 15:44:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AB65B206B8 for ; Wed, 27 Mar 2019 15:44:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727636AbfC0Pou (ORCPT ); Wed, 27 Mar 2019 11:44:50 -0400 Received: from metis.ext.pengutronix.de ([85.220.165.71]:52129 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727397AbfC0Pou (ORCPT ); Wed, 27 Mar 2019 11:44:50 -0400 Received: from kresse.hi.pengutronix.de ([2001:67c:670:100:1d::2a]) by metis.ext.pengutronix.de with esmtp (Exim 4.89) (envelope-from ) id 1h9AjI-00068E-8i; Wed, 27 Mar 2019 16:44:40 +0100 Message-ID: <1553701479.2561.38.camel@pengutronix.de> Subject: Re: [RFC 0/7] cpuidle: Add poking mechanism to support non-IPI wakeup From: Lucas Stach To: Abel Vesa , Sudeep Holla , Marc Zyngier , Rob Herring , Mark Rutland , Shawn Guo , Sascha Hauer , "catalin.marinas@arm.com" , Will Deacon , "Rafael J. Wysocki" , Lorenzo Pieralisi , Fabio Estevam , Aisheng Dong Cc: dl-linux-imx , "linux-arm-kernel@lists.infradead.org" , Linux Kernel Mailing List , "linux-pm@vger.kernel.org" Date: Wed, 27 Mar 2019 16:44:39 +0100 In-Reply-To: <1553692845-20983-1-git-send-email-abel.vesa@nxp.com> References: <1553692845-20983-1-git-send-email-abel.vesa@nxp.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1+deb9u1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::2a X-SA-Exim-Mail-From: l.stach@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Abel, Am Mittwoch, den 27.03.2019, 13:21 +0000 schrieb Abel Vesa: > This work is a workaround I'm looking into (more as a background task) > in order to add support for cpuidle on i.MX8MQ based platforms. > > The main idea here is getting around the missing GIC wake_request signal > (due to integration design issue) by waking up a each individual core through > some dedicated SW power-up bits inside the power controller (GPC) right before > every IPI is requested for that each individual core. Just a general comment, without going into the details of this series: this issue is not only affecting IPIs, but also MSIs terminated at the GIC. Currently MSIs are terminated at the PCIe core, but terminating them at the GIC is clearly preferable, as this allows assigning CPU affinity to individual MSIs and lowers IRQ service overhead. I'm not sure what the consequences are for upstream Linux support yet, but we should keep in mind that having a workaround for IPIs is only solving part of the issue. Regards, Lucas