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=-5.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 E1F99C433E0 for ; Mon, 1 Feb 2021 19:40:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD86764EA9 for ; Mon, 1 Feb 2021 19:40:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231402AbhBATkv (ORCPT ); Mon, 1 Feb 2021 14:40:51 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:59668 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229555AbhBATks (ORCPT ); Mon, 1 Feb 2021 14:40:48 -0500 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1612208406; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=VtZpA2AJJR10BLs4JGvZpp2Gn1wezLDmpF5F8OMPGRE=; b=EMEln62rnkqh9yGqgBlAHg4ORN+rRmUVEI5A0AxQE/WDb3GZdkzEZmx1HwHD/60gIDiCHL vhF1xYKzPD7+Qrvb9/Zib5GVc1Zsf1ofk4oMVUFEP4mNaCfM4p5y8U4G03VhcwBzsW+6XU quFwGd9FiH4pjhIP0v9j0MwEY/+WItOHE7l8AV1nvaBgB0LVXv0MQihEZnOSCO7VYEZWTa r57n90uOdmZJCsV90ROBoL0FAm401ZOhaI8VhH7syETRLlSYMmFf4J+UCdkolJjCEtumly uG0aONmlnLUjxfl2x6ecOfNYCozu3GTIH2eZDGSwnZlGHIehcba+HBWl060+fA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1612208406; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=VtZpA2AJJR10BLs4JGvZpp2Gn1wezLDmpF5F8OMPGRE=; b=yHRmdsqKwMr9q9mnEoOKAFUyXCNS41Y3tnu5/rDGDkEJ80GVXuFTLZNYVgHC8b5yFppPiu 0QEtPg8SYvrB6IAw== To: Linus Torvalds Cc: Serge Belyshev , Dirk Gouders , =?utf-8?Q?Micka=C3=ABl_Sala=C3=BCn?= , LKML , Alexandre Belloni , Jason Gunthorpe , Miroslav Lichvar , John Stultz , Prarit Bhargava , Alessandro Zummo , linux-rtc@vger.kernel.org, Peter Zijlstra Subject: Re: [PATCH V2] rtc: mc146818: Dont test for bit 0-5 in Register D In-Reply-To: References: <20201206214613.444124194@linutronix.de> <20201206220541.594826678@linutronix.de> <19a7753c-c492-42e4-241a-8a052b32bb63@digikod.net> <871re7hlsg.fsf@nanos.tec.linutronix.de> <98cb59e8-ecb4-e29d-0b8f-73683ef2bee7@digikod.net> <87y2gfg18p.fsf@nanos.tec.linutronix.de> <87tur3fx7w.fsf@nanos.tec.linutronix.de> <877dnrc2sv.fsf@depni.sinp.msu.ru> <8735yfd2q4.fsf@nanos.tec.linutronix.de> <87zh0nbnha.fsf@nanos.tec.linutronix.de> Date: Mon, 01 Feb 2021 20:40:06 +0100 Message-ID: <87wnvrbmqx.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 01 2021 at 11:32, Linus Torvalds wrote: > On Mon, Feb 1, 2021 at 11:24 AM Thomas Gleixner wrote: >> >> While it cures the problem on the reporters machine it breaks machines >> with Intel chipsets which use bit 0-5 of the D register. So check only >> for bit 6 being 0 which is the case on these Intel machines as well. > > This looks fine, but it might also be worth it simply just checking > for the only really special value: 0xff, and going "ok, that looks > like missing hardware". > > That's what a few other drivers historically do in their probing > routines, so it's not unheard of (ie you can find drivers doing that > kind of > > /* If we read 0xff from the LSR, there is no UART here. */ > if (inb(.. port ..) == 0xff) > > in their init routines. > > Not a big deal either way, I just think it would be more in like with > what other places do in similar situations Yeah, we can do that as well. Either way is fine. Thanks, tglx