From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756808Ab3KHIyk (ORCPT ); Fri, 8 Nov 2013 03:54:40 -0500 Received: from mail-ee0-f43.google.com ([74.125.83.43]:41634 "EHLO mail-ee0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752274Ab3KHIyj (ORCPT ); Fri, 8 Nov 2013 03:54:39 -0500 Message-ID: <527CA6CA.4010204@gmail.com> Date: Fri, 08 Nov 2013 09:54:34 +0100 From: Sebastian Hesselbarth User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 To: Jisheng Zhang CC: Arnd Bergmann , Russell King , Kevin Hilman , "linux-kernel@vger.kernel.org" , Olof Johansson , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH v3 9/9] ARM: add initial support for Marvell Berlin SoCs References: <1381235073-17134-1-git-send-email-sebastian.hesselbarth@gmail.com> <20131107134033.59bd127a@xhacker> <527B67A1.3020803@gmail.com> <201311071720.47489.arnd@arndb.de> <527C049B.4030608@gmail.com> <20131108085830.5368c92b@xhacker> In-Reply-To: <20131108085830.5368c92b@xhacker> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/08/2013 01:58 AM, Jisheng Zhang wrote: > On Thu, 7 Nov 2013 13:22:35 -0800 > Sebastian Hesselbarth wrote: >> On 11/07/2013 05:20 PM, Arnd Bergmann wrote: >>> On Thursday 07 November 2013, Sebastian Hesselbarth wrote: >>>> Actually, IIRC smp_twd does not compile without SMP set, so the above >>>> should at least be 'HAVE_ARM_TWD if SMP'. If you shrink MULTI_V7 down >>>> to non-SMP cores, you can disable it and it will fail to compile. >>> >>> If there are UP-systems for which TWD is the best clocksource, we should >>> probably fix the code to allow that configuration. IIRC there were already >>> patches recently in this area, maybe it's already solved. > > The problems is twd is not mandatory in CA9 UP system, so it may not exist. > However, I got answers from soc people, the BG2CD does configured and enabled > TWD. so we are lucky and can add HAVE_TWD for BG2CD. Jisheng, thanks for backing this up. As I said, I tried it with barebox and TWD is sufficient for a timer there. Currently, Linux requires SMP for TWD - but as you confirmed, there are non-SMP systems with TWD. The build errors below are just from a check for SMP systems, so if we remove that, TWD should be ready for non-SMP. I'll see, if I can prepare a patch next week and put it on list. Sebastian >> I just tried barebox bootloader to use TWD as timer on berlin2cd and it >> perfectly works, i.e. with time related commands I can see the timer >> register decreasing. So the timer is available on this UP SoC. > > Yep. It is available. > >> >> As said before, compiling linux without CONFIG_SMP but with >> CONFIG_HAVE_ARM_TWD gives: >> >> warning: (SOC_OMAP5 && ARCH_ROCKCHIP && ARCH_SHMOBILE_MULTI && >> MACH_BERLIN_BG2 && MACH_BERLIN_BG2CD) selects HAVE_ARM_TWD which has >> unmet direct dependencies (SMP) >> >> and >> >> arch/arm/kernel/smp_twd.c: In function 'twd_local_timer_of_register': >> arch/arm/kernel/smp_twd.c:391: error: 'setup_max_cpus' undeclared (first >> use in this function) >> arch/arm/kernel/smp_twd.c:391: error: (Each undeclared identifier is >> reported only once >> arch/arm/kernel/smp_twd.c:391: error: for each function it appears in.) >> make[1]: *** [arch/arm/kernel/smp_twd.o] Error 1 >> >> I haven't looked deeper into this, but I guess it will not be hard >> to make ARM_TWD independent of SMP.