From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CBBCFC433DF for ; Sun, 18 Oct 2020 09:51:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 574F721582 for ; Sun, 18 Oct 2020 09:51:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="Lcf4K01I" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726361AbgJRJvy (ORCPT ); Sun, 18 Oct 2020 05:51:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725320AbgJRJvx (ORCPT ); Sun, 18 Oct 2020 05:51:53 -0400 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3363DC061755; Sun, 18 Oct 2020 02:51:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=qEMPtsMLmphrg8Ai/5Jx8LIQzpGt/vPBENY1d0RHC0E=; b=Lcf4K01IIvsr9y0KWAyBU51kL tBL6KBpVPqVkHgTKZ8NomGJTe0GNS4C7pFwC22oHL20kyd6gBm2HOhmjqwLjR1cEbFQf+7z6ngNT/ yWNSWU3RKHlTp60XJzKTHAFdkMEw3CNV0oAD1Ij+wRmggkUZpZ9I5NXABiCqfoKe2SYalm2m1gfMv lMqRrXmJ/Yepa8+lc+QPNQmmsPQ3L4FlNdKxjrGwqPqeagjoYs1u3hMW1Fl0Nq2A+gHW+aJIOWHl5 GP44LwSAJ3TOpXTgLfqAJC6MsPO8dh3wlkt+tCOQkq9/WlMBajs7v0eYzw4fTWRz9k/7DT/epZdA9 nOo7Ap+lA==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:47782) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1kU5Lq-0004Al-VS; Sun, 18 Oct 2020 10:51:43 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1kU5Lm-00039F-1K; Sun, 18 Oct 2020 10:51:38 +0100 Date: Sun, 18 Oct 2020 10:51:38 +0100 From: Russell King - ARM Linux admin To: Linus Walleij Cc: Arnd Bergmann , "linux-kernel@vger.kernel.org" , Thomas Gleixner , Daniel Lezcano , John Stultz , Stephen Boyd , "David S. Miller" , Jakub Kicinski , netdev , Linux ARM Subject: Re: [PATCH 3/3] timekeeping: remove arch_gettimeoffset Message-ID: <20201018095137.GV1551@shell.armlinux.org.uk> References: <20201008154601.1901004-1-arnd@arndb.de> <20201008154601.1901004-4-arnd@arndb.de> <20201015095307.GS1551@shell.armlinux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: Russell King - ARM Linux admin Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 15, 2020 at 02:38:07PM +0200, Linus Walleij wrote: > On Thu, Oct 15, 2020 at 11:53 AM Russell King - ARM Linux admin > wrote: > > > Don't be misled. It was not a matter of "enough gritty people", it > > was a matter that EBSA110 was blocking it. > > I remember that EBSA110 was quite different in that it had this > especially limited PIT timer, true that. At one point I even read > up on the details of it and then forgot them :/ Yes, it was so basic that it required software to reprogram it on every interrupt - it had no sensible periodic mode. The side effect of which was that unless done carefully, your timekeeping varied all over the place (so much that ntpd was not happy.) The final implementation made ntpd really quite happy on the machine despite the timer's weirdness, up until Linux stopped allowing interrupts to be nested. At that point, it was back to utterly crap timekeeping. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!