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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DBC70C433EF for ; Fri, 10 Jun 2022 11:09:42 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4LKJBr68FWz3cH1 for ; Fri, 10 Jun 2022 21:09:40 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=atomide.com (client-ip=72.249.23.125; helo=muru.com; envelope-from=tony@atomide.com; receiver=) X-Greylist: delayed 435 seconds by postgrey-1.36 at boromir; Thu, 09 Jun 2022 17:46:44 AEST Received: from muru.com (muru.com [72.249.23.125]) by lists.ozlabs.org (Postfix) with ESMTP id 4LJbl807TCz3bn4 for ; Thu, 9 Jun 2022 17:46:43 +1000 (AEST) 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 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: X-Mailman-Approved-At: Fri, 10 Jun 2022 21:09:20 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juri Lelli , Rafael Wysocki , Linus Walleij , Ben Segall , Guo Ren , Pavel Machek , Alexander Gordeev , srivatsa@csail.mit.edu, linux-arch , Vincent Guittot , Huacai Chen , ACPI Devel Maling List , Andy Gross , Geert Uytterhoeven , NXP Linux Team , Catalin Marinas , xen-devel , Matt Turner , Christian Borntraeger , Michael Turquette , Sam Creasey , Petr Mladek , Linux PM list , Lai Jiangshan , Sascha Hauer , linux-um , Arnaldo Carvalho de Melo , Thomas Gleixner , linux-omap , Dietmar Eggemann , Richard Henderson , gregkh , Linux Kernel Mailing List , linux-perf-users@vger.kernel.org, Sergey Senozhatsky , Sven Schnelle , Jiri Olsa , Paul Mackerras , Mark Rutland , "open list:IA64 \(Itanium\) PLATFORM" , Dave Hansen , "open list:DRM DRIVER FOR QEMU'S CIRRUS DEVICE" , James Bottomley , Max Filippov , Thierry Reding , Xuerui Wang , quic_neeraju@quicinc.com, linux-s390 , vschneid@redhat.com, John Ogn ess , Yoshinori Sato , Linux-sh list , Fabio Estevam , Helge Deller , Daniel Lezcano , Jonathan Hunter , Mathieu Desnoyers , Frederic Weisbecker , Len Brown , "open list:TENSILICA XTENSA PORT \(xtensa\)" , Sascha Hauer , Vasily Gorbik , linux-arm-msm , alpha , linux-m68k , Stafford Horne , Linux ARM , Chris Zankel , Stephen Boyd , Dinh Nguyen , Daniel Bristot de Oliveira , Alexander Shishkin , lpieralisi@kernel.org, Rasmus Villemoes , Joel Fernandes < joel@joelfernandes.org>, Will Deacon , Boris Ostrovsky , Kevin Hilman , linux-csky@vger.kernel.org, Pv-drivers , "open list:SYNOPSYS ARC ARCHITECTURE" , Mel Gorman , jacob.jun.pan@linux.intel.com, Yury Norov , Hans Ulli Kroll , Vineet Gupta , linux-clk , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, Borislav Petkov , bcain@quicinc.com, Thomas Bogendoerfer , Parisc List , Sudeep Holla , Shawn Guo , David Miller , Rich Felker , Peter Zijlstra , amakhalov@vmware.com, Bjorn Andersson , "H. Peter Anvin" , sparclinux , "open list:QUALCOMM HEXAGON..." , linux-riscv , Anton Ivanov , Jonas Bonn , Richard Weinberger , the arch/x86 maintainers , Russell King - ARM Linux , Ingo Molnar , Albert Ou , "Paul E. McKenney" , Heiko Carstens , Stefan Kristiansson , Openrisc , Paul Walmsley , "open list:TEGRA ARCHITECTURE SUPPORT" , Namhyung Kim , Andy Shevchenko , jpoimboe@kernel.org, Juergen Gross , Michal Simek , "open list:BROADCOM NVRAM DRIVER" , Palmer Dabbelt , Anup Patel , Ivan Ko kshaysky , Johannes Berg , linuxppc-dev Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" * 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