Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756821Ab3FSNzc (ORCPT ); Wed, 19 Jun 2013 09:55:32 -0400 Received: from mail-ob0-f172.google.com ([209.85.214.172]:63401 "EHLO mail-ob0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756495Ab3FSNz2 (ORCPT ); Wed, 19 Jun 2013 09:55:28 -0400 MIME-Version: 1.0 In-Reply-To: <2791500.rs0iL4EgjJ@amdc1227> References: <1371569191-2364-1-git-send-email-t.figa@samsung.com> <8974257.1Thh8U4Een@amdc1227> <20130619132417.GB5276@e102568-lin.cambridge.arm.com> <2791500.rs0iL4EgjJ@amdc1227> Date: Wed, 19 Jun 2013 19:25:27 +0530 Message-ID: Subject: Re: [PATCH] ARM: EXYNOS: Fix incorrect usage of S5P_ARM_CORE1_* registers From: Chander Kashyap To: Tomasz Figa Cc: Lorenzo Pieralisi , Kukjin Kim , Tomasz Figa , "linux-samsung-soc@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Russell King - ARM Linux , Jingoo Han , Jonghwan Choi , Abhilash Kesavan , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , Kyungmin Park , Arnd Bergmann , Olof Johansson , Nicolas Pitre , Will Deacon , Stephen Boyd Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5503 Lines: 151 On 19 June 2013 19:19, Tomasz Figa wrote: > On Wednesday 19 of June 2013 14:24:17 Lorenzo Pieralisi wrote: >> On Wed, Jun 19, 2013 at 01:50:57PM +0100, Tomasz Figa wrote: >> > On Wednesday 19 of June 2013 17:39:21 Chander Kashyap wrote: >> > > On 18 June 2013 23:29, Kukjin Kim wrote: >> > > > On 06/19/13 02:45, Tomasz Figa wrote: >> > > >> Ccing Arnd and Olof, because I forgot to add them to git >> > > >> send-email... >> > > >> >> > > >> Sorry for the noise. >> > > >> >> > > >> On Tuesday 18 of June 2013 17:26:31 Tomasz Figa wrote: >> > > >>> S5P_ARM_CORE1_* registers affect only core 1. To control further >> > > >>> cores >> > > >>> properly another registers must be used. >> > > >>> >> > > >>> This patch replaces S5P_ARM_CORE1_* register definitions with >> > > >>> S5P_ARM_CORE_*(x) macro which return addresses of registers for >> > > >>> specified core. >> > > >>> >> > > >>> This fixes CPU hotplug on quad core Exynos SoCs on which >> > > >>> currently >> > > >>> offlining CPUs 2 or 3 caused CPU 1 to be turned off. >> > > >> >> > > >> Obviously this doesn't happen currently because of the if (cpu == >> > > >> 1), >> > > >> but> >> > > > >> > > > Yes, not happened...and just note exynos5440 doesn't support >> > > > hotplug :) >> > > > so this is available on exynos4412 and added 5420. >> > > > >> > > >> if logical cpu1 turned out not to be physical cpu1, then it would >> > > >> crash. >> > > >> >> > > >> Best regards, >> > > >> Tomasz >> > > >> >> > > >>> In addition, >> > > >>> bring-up of CPU 2 and 3 is fixed on boards where bootloader >> > > >>> powers >> > > >>> off >> > > >>> secondary cores by default. >> > > > >> > > > I need to test on board about above... >> > > > >> > > >>> Cc: stable@vger.kernel.org >> > > >>> Signed-off-by: Tomasz Figa >> > > >>> Signed-off-by: Kyungmin Park >> > > >>> --- >> > > >>> >> > > >>> arch/arm/mach-exynos/hotplug.c | 9 +++++---- >> > > >>> arch/arm/mach-exynos/include/mach/regs-pmu.h | 10 +++++++--- >> > > >>> arch/arm/mach-exynos/platsmp.c | 9 +++++---- >> > > >>> 3 files changed, 17 insertions(+), 11 deletions(-) >> > > >>> >> > > >>> diff --git a/arch/arm/mach-exynos/hotplug.c >> > > >>> b/arch/arm/mach-exynos/hotplug.c index af90cfa..c089943 100644 >> > > >>> --- a/arch/arm/mach-exynos/hotplug.c >> > > >>> +++ b/arch/arm/mach-exynos/hotplug.c >> > > >>> @@ -93,10 +93,11 @@ static inline void cpu_leave_lowpower(void) >> > > >>> >> > > >>> static inline void platform_do_lowpower(unsigned int cpu, int >> > > >>> >> > > >>> *spurious) { >> > > >>> >> > > >>> for (;;) { >> > > >>> >> > > >>> + void __iomem *reg_base; >> > > >>> + unsigned int phys_cpu = cpu_logical_map(cpu); >> > > >>> >> > > >>> - /* make cpu1 to be turned off at next WFI command >> > > >>> */ >> > > >>> - if (cpu == 1) >> > > >>> - __raw_writel(0, >> > > >>> S5P_ARM_CORE1_CONFIGURATION); >> > > >>> + reg_base = S5P_ARM_CORE_CONFIGURATION(phys_cpu); >> > > >> > > Tomasz, >> > > This will break for non-zero, MPIDR value. Say if MPIDR is 1 then >> > > for >> > > cpu0 phys_cpu value will be 0x100, >> > > and address calculation will be (S5P_ARM_CORE0_CONFIGURATION + >> > > ((0x101) * 0x80)), which is wrong. >> >> Honestly, I did not understand the reasoning above, please clarify. >> >> > Hmm, according to the code initializing __cpu_logical_map[] array this >> > is not true. >> > >> > Here's the code: >> > >> > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/tree/a >> > rch/arm/kernel/setup.c?id=refs/tags/next-20130619#n468 >> > >> > and for used macros and bitmasks: >> > >> > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/tree/a >> > rch/arm/include/asm/cputype.h?id=refs/tags/next-20130619#n45 >> > >> > Now the structure of the MPIDR register: >> > >> > http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0388e/CI >> > HEBGFG.html >> > >> > As you can see, the value read from the register in >> > smp_setup_processor_id() is only the physical CPU ID, so I don't see >> > any >> > problem here. >> >> Define "physical CPU ID" :-) >> >> There is a problem here: the MPIDR is not an index, and the >> cpu_logical_map is populated in arm_dt_init_cpu_maps in: >> >> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch >> /arm/kernel/devtree.c?id=refs/tags/v3.10-rc6 >> >> with all affinity levels. > > OK. This is what I was missing. Thanks. > >> >> You need to perform a mapping between logical cpus and registers offset, >> you can't use the cpu_logical_map directly for that. > > Hmm, can't I just extract cluster ID and CPU ID from the MPIDR value and > use them appropriately to calculate register offsets? That will create problem for multi-cluster systems. Say we have two clusters then with clusterID 0 and 1. So phys-cpu will be 0x0/0x100, 0x1/0x101 ans so on. > > Best regards, > Tomasz > >> Next accident waiting to happen is GIC code (CONFIG_GIC_NON_BANKED), >> where cpu_logical_map is used erroneously as an index. >> >> Lorenzo -- with warm regards, Chander Kashyap -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/