From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chanwoo Choi Subject: Re: [PATCHv2 8/8] ARM: dts: Add device tree sources for Exynos3250 Date: Wed, 16 Apr 2014 17:22:24 +0900 Message-ID: <534E3DC0.40502@samsung.com> References: <1397527192-21988-1-git-send-email-cw00.choi@samsung.com> <1397527192-21988-9-git-send-email-cw00.choi@samsung.com> <534CEAB7.6020600@arm.com> <534CED76.9010302@samsung.com> <534CF847.5040008@arm.com> <534CF9B4.306@samsung.com> <534CFAD7.4030508@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-reply-to: <534CFAD7.4030508@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Marc Zyngier Cc: Mark Rutland , "t.figa@samsung.com" , "kgene.kim@samsung.com" , "linux@arm.linux.org.uk" , "arnd@arndb.de" , Ian Campbell , Jaehoon Chung , "linux-samsung-soc@vger.kernel.org" , "thomas.abraham@linaro.org" , "devicetree@vger.kernel.org" , Pawel Moll , Bartlomiej Zolnierkiewicz , Inki Dae , Rob Herring , "ben-linux@fluff.org" , "linux-arm-kernel@lists.infradead.org" , "hyunhee.kim@samsung.com" , "sw0312.kim@samsung.com" , linux-ker List-Id: devicetree@vger.kernel.org Hi Marc, On 04/15/2014 06:24 PM, Marc Zyngier wrote: > On 15/04/14 10:19, Chanwoo Choi wrote: >> On 04/15/2014 06:13 PM, Marc Zyngier wrote: >>> On 15/04/14 09:27, Chanwoo Choi wrote: >>>> Hi, >>>> >>>> On 04/15/2014 05:15 PM, Marc Zyngier wrote: >>>>> On 15/04/14 02:59, Chanwoo Choi wrote: >>>>>> From: Tomasz Figa >>>>>> >>>>>> This patch add new exynos3250.dtsi to support Exynos3250 SoC based on Cortex-A7 >>>>>> dual core and includes following dt nodes: >>>>>> >>>>>> - GIC interrupt controller >>>>>> - Pinctrl to control GPIOs >>>>>> - Clock controller >>>>>> - CPU information (Cortex-A7 dual core) >>>>>> - UART to support serial port >>>>>> - MCT (Multi Core Timer) >>>>>> - ADC (Analog Digital Converter) >>>>>> - I2C/SPI bus >>>>>> - Power domain >>>>>> - PMU (Performance Monitoring Unit) >>>>>> - MSHC (Mobile Storage Host Controller) >>>>>> - PWM (Pluse Width Modulation) >>>>>> - AMBA bus >>>>> >>>>> [...] >>>>> >>>>> Where is the arch timer node? >>>> >>>> Exynos3250 uses MCT (Multi Core Timer) instead of ARM_ARCH_TIMER. >>>> - in drivers/clocksource/exynos_mct.c >>> >>> Don't you have a Cortex-A7? If so, you have the arch timer. >> >> Do you means that 'arch timer" is ARM_ARCH_TIMER? > > Yes. > >> As I knew, ARM_ARCH_TIMER is clocksource driver for system timer. >> But, Exynos SoC used MCT clocksource for system timer. >> >> Exynos dts file didn't include arch timer node but only include mct node. > > Well, it is a bug, and a recurrent one. A Cortex-A7 has the arch timers > implemented. Always. > > http://infocenter.arm.com/help/topic/com.arm.doc.ddi0464f/BABFEBJJ.html > > All Cortex-A7 have it, and so do A12, A15, A17, A53, A57. I tested 'arch_timer'(drivers/clocksource/arm_arch_timer.c) on Exynos3250 based on Cortex-A7. To test arch timer, I used the clocksource of arch_timer for timekeeping instead of clocksource of Exynos MCT. But, I faced with issue. The following function return only same value(zero) as following kernel log: - arch_counter_get_cntvct() in arch/arm/include/asm/arch_timer.h Uncompressing Linux... done, booting the kernel. [ 0.000000] Booting Linux on physical CPU 0x0 [ 0.000000] Initializing cgroup subsys cpuset [ 0.000000] Initializing cgroup subsys cpu [ 0.000000] Initializing cgroup subsys cpuacct [ 0.000000] Linux version 3.15.0-rc1-00020-gf452826-dirty ... [ 0.000000] CPU: ARMv7 Processor ... ... [ 0.000000] Architected cp15 timer(s) running at 24.00MHz (virt). [ 0.000000] sched_clock: 56 bits at 24MHz, resolution 41ns, wraps every 2863311519744ns ... Could you give me a solution to resolve this issue or a expected cause? Best Regards, Chanwoo Choi