Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030409AbaDJMHn (ORCPT ); Thu, 10 Apr 2014 08:07:43 -0400 Received: from fw-tnat.austin.arm.com ([217.140.110.23]:45828 "EHLO collaborate-mta1.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1030248AbaDJMHl (ORCPT ); Thu, 10 Apr 2014 08:07:41 -0400 From: Marc Zyngier To: Chanwoo Choi Cc: "kgene.kim\@samsung.com" , "t.figa\@samsung.com" , "linux-samsung-soc\@vger.kernel.org" , "hyunhee.kim\@samsung.com" , "sw0312.kim\@samsung.com" , "linux-kernel\@vger.kernel.org" , "yj44.cho\@samsung.com" , "inki.dae\@samsung.com" , "kyungmin.park\@samsung.com" , "linux-arm-kernel\@lists.infradead.org" Subject: Re: [PATCH 06/27] ARM: EXYNOS:: Enter a15 lowpower mode for Exynos3250 based on Cortex-a7 In-Reply-To: <534678E1.2000005@samsung.com> (Chanwoo Choi's message of "Thu, 10 Apr 2014 11:56:33 +0100") Organization: ARM Ltd References: <1397122124-15690-1-git-send-email-cw00.choi@samsung.com> <1397122124-15690-7-git-send-email-cw00.choi@samsung.com> <87d2gp3430.fsf@approximate.cambridge.arm.com> <534678E1.2000005@samsung.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) Date: Thu, 10 Apr 2014 13:07:32 +0100 Message-ID: <87mwft1j7f.fsf@approximate.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 10 2014 at 11:56:33 am BST, Chanwoo Choi wrote: > On 04/10/2014 06:51 PM, Marc Zyngier wrote: >> On Thu, Apr 10 2014 at 10:28:23 am BST, Chanwoo Choi wrote: >>> This patch decide proper lowpower mode of either a15 or a9 according to own ID >>> from Main ID register. >>> >>> Signed-off-by: Chanwoo Choi >>> Signed-off-by: Kyungmin Park >>> --- >>> arch/arm/mach-exynos/hotplug.c | 13 ++++++++++--- >>> 1 file changed, 10 insertions(+), 3 deletions(-) >>> >>> diff --git a/arch/arm/mach-exynos/hotplug.c b/arch/arm/mach-exynos/hotplug.c >>> index 5eead53..36d3db6 100644 >>> --- a/arch/arm/mach-exynos/hotplug.c >>> +++ b/arch/arm/mach-exynos/hotplug.c >>> @@ -135,13 +135,20 @@ void __ref exynos_cpu_die(unsigned int cpu) >>> int primary_part = 0; >>> >>> /* >>> - * we're ready for shutdown now, so do it. >>> - * Exynos4 is A9 based while Exynos5 is A15; check the CPU part >>> + * we're ready for shutdown now, so do it. Exynos4 is A9 based >>> + * while Exynos5 is A15/Exynos7 is A7; check the CPU part >>> * number by reading the Main ID register and then perform the >>> * appropriate sequence for entering low power. >>> */ >>> asm("mrc p15, 0, %0, c0, c0, 0" : "=r"(primary_part) : : "cc"); >> >> While you're touching that code, how about using: >> >> primary_part = read_cpuid(CPUID_ID); > > Or, > I suggest read_cpuid_part_number() instead of assembler directly. > > primary_part = read_cpuid_part_number(); Yup, even better. >> >>> - if ((primary_part & 0xfff0) == 0xc0f0) >>> + >>> + /* >>> + * Main ID register of Cortex series >>> + * - Cortex-a7 : 0x410F_C07x >>> + * - Cortex-a15 : 0x410F_C0Fx >>> + */ >>> + primary_part = primary_part & 0xfff0; >>> + if (primary_part == 0xc0f0 || primary_part == 0xc070) >> >> ARM_CPU_PART_CORTEX_A15, ARM_CPU_PART_CORTEX_A7 > > OK I'll use this defined constant as following: > > switch (primary_part) > case ARM_CPU_PART_CORTEX_A7: > case ARM_CPU_PART_CORTEX_A15: > cpu_enter_lowpower_a15(); > break; > default: > cpu_enter_lowpower_a9(); > break; > } Looks good. M. -- Jazz is not dead. It just smells funny. -- 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/