From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753529Ab3LTEV6 (ORCPT ); Thu, 19 Dec 2013 23:21:58 -0500 Received: from terminus.zytor.com ([198.137.202.10]:39391 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751838Ab3LTEV5 (ORCPT ); Thu, 19 Dec 2013 23:21:57 -0500 Message-ID: <52B3C5A6.3070805@zytor.com> Date: Thu, 19 Dec 2013 20:20:54 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: joeyli CC: "Rafael J. Wysocki" , Alessandro Zummo , Matt Fleming , Matthew Garrett , Elliott@hp.com, samer.el-haj-mahmoud@hp.com, Oliver Neukum , werner@suse.com, trenn@suse.de, JBeulich@suse.com, linux-kernel@vger.kernel.org, rtc-linux@googlegroups.com, x86@kernel.org, "linux-efi@vger.kernel.org" , linux-acpi@vger.kernel.org Subject: Re: [PATCH 03/14] rtc: block registration of rtc-cmos when CMOS RTC Not Present References: <1387439053-8711-1-git-send-email-jlee@suse.com> <1387439053-8711-4-git-send-email-jlee@suse.com> <6fc9a2f9-eae7-4588-a092-f338053ec96a@email.android.com> <1387511650.3539.4294.camel@linux-s257.site> In-Reply-To: <1387511650.3539.4294.camel@linux-s257.site> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/19/2013 07:54 PM, joeyli wrote: > Hi hpa, > > 於 四，2013-12-19 於 06:38 -0800，H. Peter Anvin 提到： >> Where did you find a platform with "no CMOS" set and a PNP RTC? I find the expect behavior in that case to be quite ambiguous and it is not at all clear to me that what you have here is the right thing. > > Actually there doesn't have the box both with "No CMOS" and PNP device. > I choice to totally block rtc-cmos driver when "No CMOS RTC" because the > definition in ACPI spec: > > CMOS RTC Not Present > > If set, indicates that the CMOS RTC is either not implemented, or > does not exist at the legacy addresses. OSPM uses the Control > Method Time and Alarm Namespace device instead. > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > It suggest us using ACPI TAD interface when this flag present. But, I > agreed your point for this is ambiguous due to ACPI spec didn't clear > define the relationship between PNP0B0x. > > Maybe we can do more detail check in cmos_init when "No CMOS RTC" set: > + check if have ACPI TAD device, then block rtc-cmos > + check if no ACPI TAD device, but have PNP0B0x, then we use PNP0b0x. > I think the only thing we should use that bit for is to inhibit the last-resort probing of I/O ports 0x70-0x73... if at all. -hpa