From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH 34.5/36] cpuidle,omap4: Push RCU-idle into omap4_enter_lowpower() Date: Wed, 15 Jun 2022 00:12:06 +0200 Message-ID: References: <20220608142723.103523089@infradead.org> <20220608144518.073801916@infradead.org> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ieYeEcrodnP9d8uMI6KazQ9YDccjAyjy/+PGF5Ov/Sc=; b=OliYmJSibamFQ0oRl2XkG2+oLG eUVxb3PF2WQS3d9O+63gY5P/Th5g3W0k/p07zjSFtfSstgpe5sY3UKPuYKK8U3d61xav16z47xA5h tkNVX1vBm9t+GM0XpJtkUArdAr+6C0D6QPwa3LyJL5W3wePUH4pa4u9UPo+aiZ0VxHDbCXoe4qfJ4 E8Y2M6s9A8SopwISJUuliIWAcL2CXospZ4jCBSi0ba1Zs/HL4wyLHhGRHBuILPFIW3paG1eAzYhHw AXd8m8CPomKQfchnKb7uAGftq4wK1SsdTGzKQsjqacjeCk0RsPVRrEJUUy3okfnQk1gM5l81agP/h arzWLEHQ==; Content-Disposition: inline In-Reply-To: List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Tony Lindgren Cc: rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, ulli.kroll@googlemail.com, linus.walleij@linaro.org, shawnguo@kernel.org, Sascha Hauer , kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, khilman@kernel.org, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, bcain@quicinc.com, chenhuacai@kernel.org, kernel@xen0n.name, geert@linux-m68k.org, sammy@sammy.net, monstr@monstr.eu, tsbogend@alpha.franken.de, dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, James.Bottomley@hansenpartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, hca@l 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)