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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4EB45C43334 for ; Thu, 9 Jun 2022 07:39:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238803AbiFIHj3 (ORCPT ); Thu, 9 Jun 2022 03:39:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40952 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237153AbiFIHj0 (ORCPT ); Thu, 9 Jun 2022 03:39:26 -0400 Received: from muru.com (muru.com [72.249.23.125]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 361E11AF1F; Thu, 9 Jun 2022 00:39:25 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id 88FEF80F1; Thu, 9 Jun 2022 07:34:50 +0000 (UTC) Date: Thu, 9 Jun 2022 10:39:22 +0300 From: Tony Lindgren To: Arnd Bergmann Cc: Peter Zijlstra , Richard Henderson , Ivan Kokshaysky , Matt Turner , Vineet Gupta , Russell King - ARM Linux , Hans Ulli Kroll , Linus Walleij , Shawn Guo , Sascha Hauer , Sascha Hauer , Fabio Estevam , NXP Linux Team , Kevin Hilman , Catalin Marinas , Will Deacon , Guo Ren , bcain@quicinc.com, Huacai Chen , Xuerui Wang , Geert Uytterhoeven , Sam Creasey , Michal Simek , Thomas Bogendoerfer , Dinh Nguyen , Jonas Bonn , Stefan Kristiansson , Stafford Horne , James Bottomley , Helge Deller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Paul Walmsley , Palmer Dabbelt , Albert Ou , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Yoshinori Sato , Rich Felker , David Miller , Richard Weinberger , Anton Ivanov , Johannes Berg , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , the arch/x86 maintainers , "H. Peter Anvin" , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Juergen Gross , srivatsa@csail.mit.edu, amakhalov@vmware.com, Pv-drivers , Boris Ostrovsky , Chris Zankel , Max Filippov , Rafael Wysocki , Len Brown , Pavel Machek , gregkh , Michael Turquette , Stephen Boyd , Daniel Lezcano , lpieralisi@kernel.org, Sudeep Holla , Andy Gross , Bjorn Andersson , Anup Patel , Thierry Reding , Jonathan Hunter , jacob.jun.pan@linux.intel.com, Yury Norov , Andy Shevchenko , Rasmus Villemoes , Steven Rostedt , Petr Mladek , Sergey Senozhatsky , John Ogness , "Paul E. McKenney" , Frederic Weisbecker , quic_neeraju@quicinc.com, Josh Triplett , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , vschneid@redhat.com, jpoimboe@kernel.org, alpha , Linux Kernel Mailing List , "open list:SYNOPSYS ARC ARCHITECTURE" , Linux ARM , linux-omap , linux-csky@vger.kernel.org, "open list:QUALCOMM HEXAGON..." , "open list:IA64 (Itanium) PLATFORM" , linux-m68k , "open list:BROADCOM NVRAM DRIVER" , Openrisc , Parisc List , linuxppc-dev , linux-riscv , linux-s390 , Linux-sh list , sparclinux , linux-um , linux-perf-users@vger.kernel.org, "open list:DRM DRIVER FOR QEMU'S CIRRUS DEVICE" , xen-devel , "open list:TENSILICA XTENSA PORT (xtensa)" , ACPI Devel Maling List , Linux PM list , linux-clk , linux-arm-msm , "open list:TEGRA ARCHITECTURE SUPPORT" , linux-arch , rcu@vger.kernel.org Subject: Re: [PATCH 33/36] cpuidle,omap3: Use WFI for omap3_pm_idle() Message-ID: References: <20220608142723.103523089@infradead.org> <20220608144518.010587032@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org * Arnd Bergmann [220608 18:18]: > On Wed, Jun 8, 2022 at 4:27 PM Peter Zijlstra wrote: > > > > arch_cpu_idle() is a very simple idle interface and exposes only a > > single idle state and is expected to not require RCU and not do any > > tracing/instrumentation. > > > > As such, omap_sram_idle() is not a valid implementation. Replace it > > with the simple (shallow) omap3_do_wfi() call. Leaving the more > > complicated idle states for the cpuidle driver. Agreed it makes sense to limit deeper idle states to cpuidle. Hopefully there is some informative splat for attempting to use arch_cpu_ide() for deeper idle states :) > I see similar code in omap2: > > omap2_pm_idle() > -> omap2_enter_full_retention() > -> omap2_sram_suspend() > > Is that code path safe to use without RCU or does it need a similar change? Seems like a similar change should be done for omap2. Then anybody who cares to implement a minimal cpuidle support can do so. Regards, Tony