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,URIBL_BLOCKED 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 ACF59C43441 for ; Sat, 24 Nov 2018 03:08:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 71F3920868 for ; Sat, 24 Nov 2018 03:08:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 71F3920868 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 S1730134AbeKXNzb (ORCPT ); Sat, 24 Nov 2018 08:55:31 -0500 Received: from kvm5.telegraphics.com.au ([98.124.60.144]:56486 "EHLO kvm5.telegraphics.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729519AbeKXNzb (ORCPT ); Sat, 24 Nov 2018 08:55:31 -0500 Received: from localhost (localhost.localdomain [127.0.0.1]) by kvm5.telegraphics.com.au (Postfix) with ESMTP id 6442C27813; Fri, 23 Nov 2018 22:08:41 -0500 (EST) Date: Sat, 24 Nov 2018 14:08:49 +1100 (AEDT) From: Finn Thain To: Michael Schmitz cc: Andreas Schwab , Linus Walleij , Geert Uytterhoeven , Arnd Bergmann , schivers@csc.com.au, Thomas Gleixner , Daniel Lezcano , 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: <9035c015-85ef-6d14-d12c-f1d5002ee49a@gmail.com> Message-ID: References: <9035c015-85ef-6d14-d12c-f1d5002ee49a@gmail.com> 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 Sat, 24 Nov 2018, Michael Schmitz wrote: > > Am 20.11.2018 um 23:02 schrieb Andreas Schwab: > > On Nov 20 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. > > > > Note that not all timers can be used freely. Some of them are > > hardwired to generate the clock for the serial interfaces. > > Timer A is used by the DMA sound driver - no workaround possible there. > > Timer B is used by the framebuffer driver, but it's used only once to > reprogram the screen base address at driver init. This one could > potentially be used after framebuffer init to improve the clocksource > accuracy. > I don't think it would make a good clocksource as MFP timers are all 8 bits wide. It could be used as a clock event device in the course of a GENERIC_CLOCKEVENTS conversion (discussed elsewhere in this thread), though the longest timed interrupt inverval would be only 21 ms. -- > Timer D is already used to generate timer interrupts used to poll the > ROM port network card / USB adapters. This timer is initialized early in > the boot process, which prevents using the MFP UART as serial console > (something that I hadn't properly considered before). I'll send a patch > for that. I'll also consider using timer B or timer C interrupts instead > to poll ROM port hardware. > > There are no serial drivers anymore that could use the MFP UART > hardware, so that point is somewhat moot at present. > > Cheers, > > Michael > > > Andreas. > > >