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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 7114DC43610 for ; Tue, 20 Nov 2018 09:30:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 44F2920671 for ; Tue, 20 Nov 2018 09:30:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 44F2920671 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=telegraphics.com.au Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727791AbeKTT6P (ORCPT ); Tue, 20 Nov 2018 14:58:15 -0500 Received: from kvm5.telegraphics.com.au ([98.124.60.144]:57180 "EHLO kvm5.telegraphics.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727155AbeKTT6P (ORCPT ); Tue, 20 Nov 2018 14:58:15 -0500 Received: from localhost (localhost.localdomain [127.0.0.1]) by kvm5.telegraphics.com.au (Postfix) with ESMTP id B576429E17; Tue, 20 Nov 2018 04:30:03 -0500 (EST) Date: Tue, 20 Nov 2018 20:30:09 +1100 (AEDT) From: Finn Thain To: Linus Walleij cc: Geert Uytterhoeven , schwab@linux-m68k.org, Arnd Bergmann , schivers@csc.com.au, Thomas Gleixner , Daniel Lezcano , schmitzmic@gmail.com, John Stultz , linux-m68k@lists.linux-m68k.org, "linux-kernel@vger.kernel.org" Subject: Re: [RFC PATCH v2 07/14] m68k: atari: Convert to clocksource API In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 20 Nov 2018, Linus Walleij wrote: > > Yes you already see the same as I see: this chip MK68901 has no less > than four timers. I bet the kernel is just using one of them, out of > habit. > > By just setting another timer as free-running we get a classic and clean > Linux clocksource for the Atari. > These are all 8-bit timers. Whereas the smallest clocksource mask I can find with grep is 24-bits. You can divide the oscillator down to 12288 Hz giving a maximum period of 20 ms. My concern would be that clocksource counter wrap could still go undetected given a little interrupt latency. > This is however a very good start in untangling the mess (as is the > whole patch series). > It should be exciting to see what happens when some of these changes get tested 8-) I've only seen results for Mac and Atari so far. > As with the Amiga, this chip also has an RTC clock that should go to the > RTC subsystem, naturally. > I think some Atari's have an MC146818, which is drivers/rtc/rtc-cmos.c, arch/alpha/kernel/rtc.c etc. -- > Yours, > Linus Walleij >