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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 DB3BCC3F68F for ; Wed, 29 Jan 2020 15:53:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B68E920716 for ; Wed, 29 Jan 2020 15:53:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726801AbgA2Px4 (ORCPT ); Wed, 29 Jan 2020 10:53:56 -0500 Received: from mga18.intel.com ([134.134.136.126]:37101 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726271AbgA2Pxz (ORCPT ); Wed, 29 Jan 2020 10:53:55 -0500 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 Jan 2020 07:53:54 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,378,1574150400"; d="scan'208";a="402025181" Received: from smile.fi.intel.com (HELO smile) ([10.237.68.40]) by orsmga005.jf.intel.com with ESMTP; 29 Jan 2020 07:53:52 -0800 Received: from andy by smile with local (Exim 4.93) (envelope-from ) id 1iwpf7-0004G2-6l; Wed, 29 Jan 2020 17:53:53 +0200 Date: Wed, 29 Jan 2020 17:53:53 +0200 From: Andy Shevchenko To: Thomas Gleixner Cc: Hans de Goede , vipul kumar , Daniel Lezcano , linux-kernel@vger.kernel.org, Stable , Srikanth Krishnakar , Cedric Hombourger , x86@kernel.org, Len Brown , Vipul Kumar Subject: Re: [v3] x86/tsc: Unset TSC_KNOWN_FREQ and TSC_RELIABLE flags on Intel Bay Trail SoC Message-ID: <20200129155353.GI32742@smile.fi.intel.com> References: <87iml11ccf.fsf@nanos.tec.linutronix.de> <87ftg5131x.fsf@nanos.tec.linutronix.de> <30d49be8-67ad-6f32-37a8-0cdd26f0852e@redhat.com> <87sgjz434v.fsf@nanos.tec.linutronix.de> <20200129130350.GD32742@smile.fi.intel.com> <0d361322-87aa-af48-492c-e8c4983bb35b@redhat.com> <20200129141444.GE32742@smile.fi.intel.com> <91cdda7a-4194-ebe7-225d-854447b0436e@redhat.com> <87imku2t3w.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87imku2t3w.fsf@nanos.tec.linutronix.de> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 29, 2020 at 04:13:39PM +0100, Thomas Gleixner wrote: > Hans de Goede writes: > > On 29-01-2020 15:14, Andy Shevchenko wrote: > >>> The only one which is possibly suspicious here is this line: > >>> > >>> * 0111: 25 * 32 / 9 = 88.8889 MHz > >>> > >>> The SDM says 88.9 MHz for this one. > > I trust math more than the SDM :) > > >> Anyway it seems need to be fixed as well. > >> > >> Btw, why we are mentioning 20 / 6 and 28 / 6 when arithmetically > >> it's the same as 10 / 3 and 14 / 3? > > > > I copied the BYT values from Thomas' email and I guess he did not > > get around to simplifying them, I'll use the simplified versions > > for my patch. > > Too tired, too lazy :) > > Andy, can you please make sure that people inside Intel who can look > into the secrit documentation confirm what we are aiming for? > > Ideally they should provide the X-tal frequency and the mult/div pair > themself :) So, I don't have access to the CPU core documentation (and may be will not be given), nevertheless I dug a bit to what I have for Cherrytrail. So, the XTAL is 19.2MHz, which becomes 100MHz and 1600MHz by some root PLL, then, the latter two frequencies are being used by another PLL to provide a reference clock (*) to PLL which derives CPU clock. *) According to colleagues of mine it's a fixed rate source. That's all what I have. -- With Best Regards, Andy Shevchenko