From mboxrd@z Thu Jan 1 00:00:00 1970 From: Krzysztof Kozlowski Subject: Re: [PATCH 0/1] ARM: dts: exynos: Add timer node for exynos5420 Date: Mon, 04 Apr 2016 10:57:01 +0900 Message-ID: <5701C9ED.2080303@samsung.com> References: <56FA539F.1000208@samsung.com> <57017F8A.6030307@free.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mailout2.w1.samsung.com ([210.118.77.12]:60857 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751018AbcDDB5J (ORCPT ); Sun, 3 Apr 2016 21:57:09 -0400 Received: from eucpsbgm1.samsung.com (unknown [203.254.199.244]) by mailout2.w1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTP id <0O5300AO96R5Q670@mailout2.w1.samsung.com> for linux-samsung-soc@vger.kernel.org; Mon, 04 Apr 2016 02:57:05 +0100 (BST) In-reply-to: <57017F8A.6030307@free.fr> Sender: linux-samsung-soc-owner@vger.kernel.org List-Id: linux-samsung-soc@vger.kernel.org To: Adel Belhouane , Kukjin Kim , linux-samsung-soc@vger.kernel.org On 04.04.2016 05:39, Adel Belhouane wrote: > Le 29/03/2016 12:06, Krzysztof Kozlowski a =E9crit : >> Please look at this thread: >> http://lists.infradead.org/pipermail/linux-arm-kernel/2015-July/3598= 06.html >> >> Unfortunately I do not have any more details about this. >=20 > So I understand MCT and Arch Timer use the same hardware timer and > there were issues when the MCT interface reset it at boot and during > resume and the Arch Timer consumers didn't expect it. In this thread = there > were links [1] to a patch to have the MCT not writing the timer anymo= re, > thus allowing the two interfaces to co-exist. >=20 > This patch was applied in commit 1d80415db64b. So no problem is to be > expected when using both interfaces at the same time. >=20 > I can see exynos5250 got its Arch Timer definition for KVM: >=20 > - From the description of commit 2b7da98870bc > ARM: dts: Add architected timer nodes for exynos5250 > [...] > This is required by KVM. >=20 > So is there something else blocking adding this definition for 542x/5= 800 > considering its effect is enabling KVM ? Yeah, this is blocking: > Doug Anderson: > According to Samsung, there are issues where using cp15 could > sometimes return the wrong value, especially if you happen to read it > while on an A7 instead of an A15. > Kukjin Kim: > One more thing, if you change it for your own private platform, it's = > up > to you but if not, i.e., for mass product, please don't change it. > Because it's not guaranteed even you haven't seen its failure... Best regards, Krzysztof