From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754374AbbAPADM (ORCPT ); Thu, 15 Jan 2015 19:03:12 -0500 Received: from mailout4.samsung.com ([203.254.224.34]:25713 "EHLO mailout4.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754046AbbAPADJ (ORCPT ); Thu, 15 Jan 2015 19:03:09 -0500 X-AuditID: cbfee691-f79b86d000004a5a-01-54b855391de9 Message-id: <54B85539.7090908@samsung.com> Date: Fri, 16 Jan 2015 09:03:05 +0900 From: Chanwoo Choi User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130106 Thunderbird/17.0.2 MIME-version: 1.0 To: Mark Rutland Cc: Chanwoo Choi , "linux-samsung-soc@vger.kernel.org" , Daniel Lezcano , Doug Anderson , "linux-kernel@vger.kernel.org" , "inki.dae@samsung.com" , Kukjin Kim , Olof Johansson , Kukjin Kim , "tglx@linutronix.de" , "linux-arm-kernel@lists.infradead.org" Subject: Re: [RESEND PATCH v3] clocksource: exynos_mct: Add the support for Exynos 64bit SoC References: <1421213603-5020-1-git-send-email-cw00.choi@samsung.com> <54B69072.4080607@kernel.org> <54B692FB.7030703@linaro.org> <54B7024C.4020407@samsung.com> <20150115112938.GB16217@leverpostej> <20150115133404.GF16217@leverpostej> In-reply-to: <20150115133404.GF16217@leverpostej> Content-type: text/plain; charset=ISO-8859-1 Content-transfer-encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrCIsWRmVeSWpSXmKPExsWyRsSkUNcydEeIwe1dWhbPjmpbzPssa3F2 2UE2i0n3J7BY9C64ymbR//g1s8Wmx9dYLS7vmsNmMeP8PiaLpdcvMlmcuv6ZzWLzpqnMDjwe a+atYfSY3XCRxWPnrLvsHptWdbJ53Lm2h83j3blz7B6bl9R7XDnRxOrRt2UVo8fnTXIBXFFc NimpOZllqUX6dglcGWfXTGQpOChX0XJvDXsD43mJLkYODgkBE4n7lzS6GDmBTDGJC/fWs3Ux cnEICSxllLjyegYzRMJE4vHCR1CJ6YwSrT/amSCc14wSC2bfA6viFdCSmLG4jxXEZhFQleh8 9JEdxGYDiu9/cYMNxBYVCJNYOf0KC0S9oMSPyffAbBEBdYmeXV9YQIYyC8xlkejZNw2sWVgg TuL3kc0sENv+Mkn8WvsFbBKngKHEpyX7wbYxC+hI7G+dxgZhy0tsXvOWGaRBQmAih8T+OTuY IU4SkPg2+RALxNOyEpsOQP0mKXFwxQ2WCYxis5AcNQvJ2FlIxi5gZF7FKJpakFxQnJReZKpX nJhbXJqXrpecn7uJERjZp/89m7iD8f4B60OMAhyMSjy8jH7bQ4RYE8uKK3MPMZoCXTGRWUo0 OR+YPvJK4g2NzYwsTE1MjY3MLc2UxHl1pH8GCwmkJ5akZqemFqQWxReV5qQWH2Jk4uCUamBs c3Rc8sGgaItfeP3B+cmzpm7l5VnlXqmec54vY0Vmn3G1cURP/M4/ngKav0Wq0mY0vgrJ4xXN jcnIMd9roPHvV3RVxeF8/vNBX/yzVp75Ga1R+dFhu7/a9bpdE33CDRYrXeRf2La1xuuSXfP3 6GAJzbvs/LznnDbycxyVm/v729Ti/Qw3tyixFGckGmoxFxUnAgCDldp95wIAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprPKsWRmVeSWpSXmKPExsVy+t9jQV3L0B0hBusXKlo8O6ptMe+zrMXZ ZQfZLCbdn8Bi0bvgKptF/+PXzBabHl9jtbi8aw6bxYzz+5gsll6/yGRx6vpnNovNm6YyO/B4 rJm3htFjdsNFFo+ds+6ye2xa1cnmcefaHjaPd+fOsXtsXlLvceVEE6tH35ZVjB6fN8kFcEU1 MNpkpCampBYppOYl56dk5qXbKnkHxzvHm5oZGOoaWlqYKynkJeam2iq5+AToumXmAJ2tpFCW mFMKFApILC5W0rfDNCE0xE3XAqYxQtc3JAiux8gADSSsYcw4u2YiS8FBuYqWe2vYGxjPS3Qx cnJICJhIPF74iA3CFpO4cG89kM3FISQwnVGi9Uc7E4TzmlFiwex7zCBVvAJaEjMW97GC2CwC qhKdjz6yg9hsQPH9L26ATRIVCJNYOf0KC0S9oMSPyffAbBEBdYmeXV9YQIYyC8xlkejZNw2s WVggTuL3kc0sENv+Mkn8WvsFbBKngKHEpyX7wbYxC+hI7G+dxgZhy0tsXvOWeQKjwCwkS2Yh KZuFpGwBI/MqRtHUguSC4qT0XEO94sTc4tK8dL3k/NxNjODE8UxqB+PKBotDjAIcjEo8vAx+ 20OEWBPLiitzDzFKcDArifDyMu8IEeJNSaysSi3Kjy8qzUktPsRoCgyDicxSosn5wKSWVxJv aGxiZmRpZG5oYWRsriTOq2TfFiIkkJ5YkpqdmlqQWgTTx8TBKdXAmBRaZegZlqJ1cfKP18ud d5/paQ/cX3H6o/S+0tcrf+41/nH6q8BK1dN8MWsl6k+pBZx7vySrMPsZ48nYjfnHJqz5+fnM QmPz5NM2Qru3PLnuEvFTM2imT0+08uyFPq6nwpv/KbqW3Hj+SPjB/7KkuMjZCSoF/BHzKtcW vPrYGcVzq/PLy2AhdyWW4oxEQy3mouJEAIXMexgyAwAA DLP-Filter: Pass X-MTR: 20000000000000000@CPGS X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/15/2015 10:34 PM, Mark Rutland wrote: > On Thu, Jan 15, 2015 at 12:52:38PM +0000, Chanwoo Choi wrote: >> On Thu, Jan 15, 2015 at 9:46 PM, Chanwoo Choi wrote: >>> Hi Mark, >>> >>> On Thu, Jan 15, 2015 at 8:29 PM, Mark Rutland wrote: >>>> On Wed, Jan 14, 2015 at 11:57:00PM +0000, Chanwoo Choi wrote: >>>>> Hi Kukjin, >>>>> >>>>> On 01/15/2015 01:02 AM, Daniel Lezcano wrote: >>>>>> On 01/14/2015 04:51 PM, Kukjin Kim wrote: >>>>>>> On 01/14/15 14:33, Chanwoo Choi wrote: >>>>>>> >>>>>>> Hi, >>>>>>> >>>>>>> + Doug, Olof >>>>>>> >>>>>>>> This patch adds the support for Exynos 64bit SoC. The delay_timer is only used >>>>>>>> for Exynos 32bit SoC. >>>>>>>> >>>>>>> Yes, the Exynos MCT(Multi-Core Timer) is 64bit timer and it is available >>>>>>> on 64bit exynos SoC such as exynos7. But basically ARMv8 architecture is >>>>>>> including ARM ARCH timer (ARM Generic Timer) and exynos7 also has >>>>>>> implemented it and additionally its access is faster than using memory >>>>>>> mapped register called SFR for MCT...so Doug submitted patch to use MCT >>>>>>> on 32bit exynos SoCs before. >>>>> >>>>> I know arch_timer. As you comment, ARCH timer would be used for system timer for ARMv8. >>>>> But, Exynos5433/Exynos7 (ARMv8) include MCT (Multi-Core Timer) IP. I checked it on >>>>> Exynos5433/EXynos7 User-manaual and tested it. >>>>> >>>>> I think that exynos_mct.c should support the Exynos 64-bit SoC >>>>> because Exynos5433/Exynos7 include already MCT (Multi-Core Timer) IP. >>>>> >>>>> Also, I have a problem to verify ARCH timer on Exynos SoC. Exynos User-manual never includes >>>>> the detailed information about for ARCH timer(e.g, clock for ARCH timer). I knew that >>>>> I can get the document of ARCH timer for ARM official site but I think it is insufficient >>>>> to implement ARCH timer on Exynos SoC. >>>> >>>> What do you mean by "insufficient to implement ARCH timer"? >>> >>> As I knew, timer must need the source clock. The clock for ARCH timer >>> has dependency on Exynos SoC, But I cannot find >> >> I'm so sorry about this mistake. I pressed the send button before >> completing reply. >> >> As I knew, timer must need the source clock. The clock for ARCH timer >> has dependency on Exynos SoC, But I cannot find the clock information >> for ARCH timer on Exynos SoC user-manual. >> >> When I tried to use ARCH timer on Exynos3250, It is not working. We >> can check this ARCH timer issue of Exynos3250 >> on following patch[1]: >> [1] http://www.spinics.net/lists/arm-kernel/msg322943.html > > Hmm. That is annoying. Your boot code should have been initialising this > already. Right, I want to resolve the issue for Exynos3250 but I don't have any information. Maybe this issue should be fixed by the architector of Exynos SoC or any samsung developer who can contact the information of ARCH timer. > >>>> The architected timer is mandatory in ARMv8, and required by the arm64 >>>> kernel. >>>> >>>> Additional timers may be requried if you want to put all CPUs into low >>>> power states where the timer logic may be disabled and/or lose state, >>>> but regardless the architected timers are necessary. >> >> I agree that ARCH timer is mandatory. >> >> I just think that existing exynos-mct.c driver should support the Exynos5/7 SoC >> because released Exynos5/7 SoC includes already MCT IP for system timer. > > I'm not opposed to the MCT. My only concern is that a configured and > enabled architected timer is mandated by the boot protocol, and is a > prerequisite for a functioning kernel. Thanks for your opinion. As I replyed on previous mail, I agree that ARCH timer is necessary. Your initial response made it > sound like you expected the MCT alone to be sufficient. I didn't mean it. Best Regards, Chanwoo Choi