From patchwork Tue Jul 5 17:29:17 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stephen Boyd X-Patchwork-Id: 945882 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter2.kernel.org (8.14.4/8.14.4) with ESMTP id p65HTLQ0004366 for ; Tue, 5 Jul 2011 17:29:22 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754737Ab1GER3V (ORCPT ); Tue, 5 Jul 2011 13:29:21 -0400 Received: from wolverine01.qualcomm.com ([199.106.114.254]:26973 "EHLO wolverine01.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752958Ab1GER3T (ORCPT ); Tue, 5 Jul 2011 13:29:19 -0400 X-IronPort-AV: E=McAfee;i="5400,1158,6398"; a="101903465" Received: from pdmz-ns-mip.qualcomm.com (HELO mostmsg01.qualcomm.com) ([199.106.114.10]) by wolverine01.qualcomm.com with ESMTP/TLS/ADH-AES256-SHA; 05 Jul 2011 10:29:19 -0700 Received: from sboyd-linux.qualcomm.com (pdmz-snip-v218.qualcomm.com [192.168.218.1]) by mostmsg01.qualcomm.com (Postfix) with ESMTPA id 2C82810004DC; Tue, 5 Jul 2011 10:29:19 -0700 (PDT) From: Stephen Boyd To: Russell King Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-omap@vger.kernel.org, linux-sh@vger.kernel.org, linux-tegra@vger.kernel.org, Paul Mundt , Kukjin Kim , David Brown , Tony Lindgren , Srinidhi Kasagar , Linus Walleij Subject: [PATCHv2] arm: platsmp: Allow secondary cpu hotplug with maxcpus=1 Date: Tue, 5 Jul 2011 10:29:17 -0700 Message-Id: <1309886957-7548-1-git-send-email-sboyd@codeaurora.org> X-Mailer: git-send-email 1.7.6.131.g99019 Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter2.kernel.org [140.211.167.43]); Tue, 05 Jul 2011 17:29:22 +0000 (UTC) If an ARM system has multiple cpus in the same socket and the kernel is booted with maxcpus=1, secondary cpus are possible but not present due to how platform_smp_prepare_cpus() is called. Since most typical ARM processors don't actually support physical hotplug, initialize the present map to be equal to the possible map in generic ARM SMP code. Also, always call platform_smp_prepare_cpus() as long as max_cpus is non-zero (0 means no SMP) to allow platform code to do any SMP setup. After applying this patch it's possible to boot an ARM system with maxcpus=1 on the command line and then hotplug in secondary cpus via sysfs. This is more in line with how x86 does things. Signed-off-by: Stephen Boyd Cc: Paul Mundt Cc: Kukjin Kim Cc: David Brown Cc: Tony Lindgren Cc: Srinidhi Kasagar Cc: Linus Walleij --- Changes since V1: * Pulled up init_cpu_present() to arm/kernel/smp.c instead of in each platform_smp_prepare_cpus() arch/arm/kernel/smp.c | 11 +++++++++-- arch/arm/mach-exynos4/platsmp.c | 8 -------- arch/arm/mach-msm/platsmp.c | 8 -------- arch/arm/mach-omap2/omap-smp.c | 8 -------- arch/arm/mach-realview/platsmp.c | 8 -------- arch/arm/mach-shmobile/platsmp.c | 5 ----- arch/arm/mach-tegra/platsmp.c | 8 -------- arch/arm/mach-ux500/platsmp.c | 8 -------- arch/arm/mach-vexpress/ct-ca9x4.c | 4 ---- 9 files changed, 9 insertions(+), 59 deletions(-) diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index e7f92a4..167e3cb 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -365,8 +365,7 @@ void __init smp_prepare_cpus(unsigned int max_cpus) */ if (max_cpus > ncores) max_cpus = ncores; - - if (max_cpus > 1) { + if (ncores > 1 && max_cpus) { /* * Enable the local timer or broadcast device for the * boot CPU, but only if we have more than one CPU. @@ -374,6 +373,14 @@ void __init smp_prepare_cpus(unsigned int max_cpus) percpu_timer_setup(); /* + * Initialise the present map, which describes the set of CPUs + * actually populated at the present time. A platform should + * re-initialize the map in platform_smp_prepare_cpus() if + * present != possible (e.g. physical hotplug). + */ + init_cpu_present(&cpu_possible_map); + + /* * Initialise the SCU if there are more than one CPU * and let them know where to start. */ diff --git a/arch/arm/mach-exynos4/platsmp.c b/arch/arm/mach-exynos4/platsmp.c index c5e65a0..b68d5bd 100644 --- a/arch/arm/mach-exynos4/platsmp.c +++ b/arch/arm/mach-exynos4/platsmp.c @@ -154,14 +154,6 @@ void __init smp_init_cpus(void) void __init platform_smp_prepare_cpus(unsigned int max_cpus) { - int i; - - /* - * Initialise the present map, which describes the set of CPUs - * actually populated at the present time. - */ - for (i = 0; i < max_cpus; i++) - set_cpu_present(i, true); scu_enable(scu_base_addr()); diff --git a/arch/arm/mach-msm/platsmp.c b/arch/arm/mach-msm/platsmp.c index 2034098..315b9f3 100644 --- a/arch/arm/mach-msm/platsmp.c +++ b/arch/arm/mach-msm/platsmp.c @@ -157,12 +157,4 @@ void __init smp_init_cpus(void) void __init platform_smp_prepare_cpus(unsigned int max_cpus) { - int i; - - /* - * Initialise the present map, which describes the set of CPUs - * actually populated at the present time. - */ - for (i = 0; i < max_cpus; i++) - set_cpu_present(i, true); } diff --git a/arch/arm/mach-omap2/omap-smp.c b/arch/arm/mach-omap2/omap-smp.c index ecfe93c..ce65e93 100644 --- a/arch/arm/mach-omap2/omap-smp.c +++ b/arch/arm/mach-omap2/omap-smp.c @@ -125,14 +125,6 @@ void __init smp_init_cpus(void) void __init platform_smp_prepare_cpus(unsigned int max_cpus) { - int i; - - /* - * Initialise the present map, which describes the set of CPUs - * actually populated at the present time. - */ - for (i = 0; i < max_cpus; i++) - set_cpu_present(i, true); /* * Initialise the SCU and wake up the secondary core using diff --git a/arch/arm/mach-realview/platsmp.c b/arch/arm/mach-realview/platsmp.c index 963bf0d..4ae943b 100644 --- a/arch/arm/mach-realview/platsmp.c +++ b/arch/arm/mach-realview/platsmp.c @@ -68,14 +68,6 @@ void __init smp_init_cpus(void) void __init platform_smp_prepare_cpus(unsigned int max_cpus) { - int i; - - /* - * Initialise the present map, which describes the set of CPUs - * actually populated at the present time. - */ - for (i = 0; i < max_cpus; i++) - set_cpu_present(i, true); scu_enable(scu_base_addr()); diff --git a/arch/arm/mach-shmobile/platsmp.c b/arch/arm/mach-shmobile/platsmp.c index f3888fe..66f9806 100644 --- a/arch/arm/mach-shmobile/platsmp.c +++ b/arch/arm/mach-shmobile/platsmp.c @@ -64,10 +64,5 @@ void __init smp_init_cpus(void) void __init platform_smp_prepare_cpus(unsigned int max_cpus) { - int i; - - for (i = 0; i < max_cpus; i++) - set_cpu_present(i, true); - shmobile_smp_prepare_cpus(); } diff --git a/arch/arm/mach-tegra/platsmp.c b/arch/arm/mach-tegra/platsmp.c index b8ae3c9..1a594dc 100644 --- a/arch/arm/mach-tegra/platsmp.c +++ b/arch/arm/mach-tegra/platsmp.c @@ -129,14 +129,6 @@ void __init smp_init_cpus(void) void __init platform_smp_prepare_cpus(unsigned int max_cpus) { - int i; - - /* - * Initialise the present map, which describes the set of CPUs - * actually populated at the present time. - */ - for (i = 0; i < max_cpus; i++) - set_cpu_present(i, true); scu_enable(scu_base); } diff --git a/arch/arm/mach-ux500/platsmp.c b/arch/arm/mach-ux500/platsmp.c index 0c527fe..a33df5f 100644 --- a/arch/arm/mach-ux500/platsmp.c +++ b/arch/arm/mach-ux500/platsmp.c @@ -172,14 +172,6 @@ void __init smp_init_cpus(void) void __init platform_smp_prepare_cpus(unsigned int max_cpus) { - int i; - - /* - * Initialise the present map, which describes the set of CPUs - * actually populated at the present time. - */ - for (i = 0; i < max_cpus; i++) - set_cpu_present(i, true); scu_enable(scu_base_addr()); wakeup_secondary(); diff --git a/arch/arm/mach-vexpress/ct-ca9x4.c b/arch/arm/mach-vexpress/ct-ca9x4.c index 765a71f..bfd32f5 100644 --- a/arch/arm/mach-vexpress/ct-ca9x4.c +++ b/arch/arm/mach-vexpress/ct-ca9x4.c @@ -229,10 +229,6 @@ static void ct_ca9x4_init_cpu_map(void) static void ct_ca9x4_smp_enable(unsigned int max_cpus) { - int i; - for (i = 0; i < max_cpus; i++) - set_cpu_present(i, true); - scu_enable(MMIO_P2V(A9_MPCORE_SCU)); } #endif