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Received: from dhcp-077-249-017-003.chello.nl ([77.249.17.3] helo=worktop.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1o1Elc-000Y9d-O5; Tue, 14 Jun 2022 22:12:08 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id ED8F2981518; Wed, 15 Jun 2022 00:12:06 +0200 (CEST) Date: Wed, 15 Jun 2022 00:12:06 +0200 From: Peter Zijlstra To: Tony Lindgren Subject: Re: [PATCH 34.5/36] cpuidle,omap4: Push RCU-idle into omap4_enter_lowpower() Message-ID: References: <20220608142723.103523089@infradead.org> <20220608144518.073801916@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Mailman-Approved-At: Thu, 16 Jun 2022 11:54:30 +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@redhat.com, rafael@kernel.org, linus.walleij@linaro.org, bsegall@google.com, guoren@kernel.org, pavel@ucw.cz, agordeev@linux.ibm.com, srivatsa@csail.mit.edu, linux-arch@vger.kernel.org, vincent.guittot@linaro.org, chenhuacai@kernel.org, linux-acpi@vger.kernel.org, agross@kernel.org, geert@linux-m68k.org, linux-imx@nxp.com, catalin.marinas@arm.com, xen-devel@lists.xenproject.org, mattst88@gmail.com, borntraeger@linux.ibm.com, mturquette@baylibre.com, sammy@sammy.net, pmladek@suse.com, linux-pm@vger.kernel.org, jiangshanlai@gmail.com, Sascha Hauer , linux-um@lists.infradead.org, acme@kernel.org, tglx@linutronix.de, linux-omap@vger.kernel.org, dietmar.eggemann@arm.com, rth@twiddle.net, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, senozhatsky@chromium.org, svens@linux.ibm.com, jolsa@kernel.org, paulus@samba.org, mark.rutland@arm.com, linux-ia64@vger.kernel.org, dave.hansen@linux.intel.com, virtualizatio n@lists.linux-foundation.org, James.Bottomley@hansenpartnership.com, jcmvbkbc@gmail.com, thierry.reding@gmail.com, kernel@xen0n.name, quic_neeraju@quicinc.com, linux-s390@vger.kernel.org, vschneid@redhat.com, john.ogness@linutronix.de, ysato@users.sourceforge.jp, linux-sh@vger.kernel.org, festevam@gmail.com, deller@gmx.de, daniel.lezcano@linaro.org, jonathanh@nvidia.com, mathieu.desnoyers@efficios.com, frederic@kernel.org, lenb@kernel.org, linux-xtensa@linux-xtensa.org, kernel@pengutronix.de, gor@linux.ibm.com, linux-arm-msm@vger.kernel.org, linux-alpha@vger.kernel.org, linux-m68k@lists.linux-m68k.org, shorne@gmail.com, linux-arm-kernel@lists.infradead.org, chris@zankel.net, sboyd@kernel.org, dinguyen@kernel.org, bristot@redhat.com, alexander.shishkin@linux.intel.com, lpieralisi@kernel.org, linux@rasmusvillemoes.dk, joel@joelfernandes.org, will@kernel.org, boris.ostrovsky@oracle.com, khilman@kernel.org, linux-csky@vger.kernel.org, linux-snps-arc@lists.infradead.org, mgorman@suse.de, jacob.jun.pan@linux.intel.com, Arnd Bergmann , ulli.kroll@googlemail.com, vgupta@kernel.org, linux-clk@vger.kernel.org, josh@joshtriplett.org, rostedt@goodmis.org, rcu@vger.kernel.org, bp@alien8.de, bcain@quicinc.com, tsbogend@alpha.franken.de, linux-parisc@vger.kernel.org, sudeep.holla@arm.com, shawnguo@kernel.org, davem@davemloft.net, dalias@libc.org, pv-drivers@vmware.com, amakhalov@vmware.com, bjorn.andersson@linaro.org, hpa@zytor.com, sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-riscv@lists.infradead.org, anton.ivanov@cambridgegreys.com, jonas@southpole.se, yury.norov@gmail.com, richard@nod.at, x86@kernel.org, linux@armlinux.org.uk, mingo@redhat.com, aou@eecs.berkeley.edu, paulmck@kernel.org, hca@linux.ibm.com, stefan.kristiansson@saunalahti.fi, openrisc@lists.librecores.org, paul.walmsley@sifive.com, linux-tegra@vger.kernel.org, namhyung@kernel.org, andriy.shevchenko@linux.intel.com, jpoimboe@kernel.org, jgross@suse.com, monstr@monstr.eu, linux-mips@vger.kernel.org, palmer@dabbelt.com, anup@bra infault.org, ink@jurassic.park.msu.ru, johannes@sipsolutions.net, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon, Jun 13, 2022 at 03:39:05PM +0300, Tony Lindgren wrote: > OMAP4 uses full SoC suspend modes as idle states, as such it needs the > whole power-domain and clock-domain code from the idle path. > > All that code is not suitable to run with RCU disabled, as such push > RCU-idle deeper still. > > Signed-off-by: Tony Lindgren > --- > > Peter here's one more for your series, looks like this is needed to avoid > warnings similar to what you did for omap3. Thanks Tony! I've had a brief look at omap2_pm_idle() and do I understand it right that something like the below patch would reduce it to a simple 'WFI'? What do I do with the rest of that code, because I don't think this thing has a cpuidle driver to take over, effectively turning it into dead code. --- a/arch/arm/mach-omap2/pm24xx.c +++ b/arch/arm/mach-omap2/pm24xx.c @@ -126,10 +126,20 @@ static int omap2_allow_mpu_retention(voi return 1; } -static void omap2_enter_mpu_retention(void) +static void omap2_do_wfi(void) { const int zero = 0; + /* WFI */ + asm("mcr p15, 0, %0, c7, c0, 4" : : "r" (zero) : "memory", "cc"); +} + +#if 0 +/* + * possible cpuidle implementation between WFI and full_retention above + */ +static void omap2_enter_mpu_retention(void) +{ /* The peripherals seem not to be able to wake up the MPU when * it is in retention mode. */ if (omap2_allow_mpu_retention()) { @@ -146,8 +157,7 @@ static void omap2_enter_mpu_retention(vo pwrdm_set_next_pwrst(mpu_pwrdm, PWRDM_POWER_ON); } - /* WFI */ - asm("mcr p15, 0, %0, c7, c0, 4" : : "r" (zero) : "memory", "cc"); + omap2_do_wfi(); pwrdm_set_next_pwrst(mpu_pwrdm, PWRDM_POWER_ON); } @@ -161,6 +171,7 @@ static int omap2_can_sleep(void) return 1; } +#endif static void omap2_pm_idle(void) { @@ -169,6 +180,7 @@ static void omap2_pm_idle(void) if (omap_irq_pending()) return; +#if 0 error = cpu_cluster_pm_enter(); if (error || !omap2_can_sleep()) { omap2_enter_mpu_retention(); @@ -179,6 +191,9 @@ static void omap2_pm_idle(void) out_cpu_cluster_pm: cpu_cluster_pm_exit(); +#else + omap2_do_wfi(); +#endif } static void __init prcm_setup_regs(void)