Re: [PATCH 34.5/36] cpuidle,omap4: Push RCU-idle into omap4_enter_lowpower()
From: Peter Zijlstra <peterz@infradead.org>
Date: 2022-06-14 22:12:47
Also in:
linux-acpi, linux-alpha, linux-arch, linux-arm-msm, linux-clk, linux-m68k, linux-mips, linux-omap, linux-perf-users, linux-pm, linux-riscv, linux-s390, linux-sh, linux-tegra, linux-um, lkml, rcu, sparclinux, virtualization, xen-devel
rndb.de>, 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" [off-list ref] 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 <tony@atomide.com> --- 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)