Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752016AbbF3UMq (ORCPT ); Tue, 30 Jun 2015 16:12:46 -0400 Received: from mail-wi0-f170.google.com ([209.85.212.170]:35503 "EHLO mail-wi0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752130AbbF3UMg (ORCPT ); Tue, 30 Jun 2015 16:12:36 -0400 MIME-Version: 1.0 In-Reply-To: <1434666968-1543-2-git-send-email-al.stone@linaro.org> References: <1434666968-1543-1-git-send-email-al.stone@linaro.org> <1434666968-1543-2-git-send-email-al.stone@linaro.org> Date: Tue, 30 Jun 2015 22:12:34 +0200 X-Google-Sender-Auth: itI9HaZ14G1tA8eqkE4fGsDFSpw Message-ID: Subject: Re: [PATCH v2 1/3] ACPI : introduce macros for using the ACPI specification version From: "Rafael J. Wysocki" To: Al Stone Cc: ACPI Devel Maling List , "linux-arm-kernel@lists.infradead.org" , "Rafael J. Wysocki" , Len Brown , Catalin Marinas , Will Deacon , Thomas Gleixner , Jason Cooper , Linux Kernel Mailing List , "linaro-acpi@lists.linaro.org" , Lists linaro-kernel , "patches@linaro.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1878 Lines: 53 Hi Al, On Fri, Jun 19, 2015 at 12:36 AM, Al Stone wrote: > Add the ACPI_SPEC_VERSION() macro to build a proper version number from > a major and minor revision number. Add also the ACPI_FADT_SPEC_VERSION > that constructs a proper version number from the entries in the current > FADT. > > These macros are added in order to simplify retrieving and comparing ACPI > specification version numbers, since this is becoming a more frequent need. > In particular, there are some architectures that require at least a certain > version of the spec, and there are differences in some structure sizes that > have changed with recent versions but can only be tracked by spec version > number. > > Signed-off-by: Al Stone > --- > include/linux/acpi.h | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > index a4acb55..33ed313 100644 > --- a/include/linux/acpi.h > +++ b/include/linux/acpi.h > @@ -48,6 +48,11 @@ > #include > #include > > +#define ACPI_SPEC_VERSION(major, minor) ((major<<8)|minor) One nit here. acpi_gbl_FADT.header.revision is of type u8 originally, so shifting it by 8 bit positions only works due to some implicit type casting I suppose. Moreover, it is not entirely clear why the macro is specific to the computation of the ACPI spec version. So I'd drop ACPI_SPEC_VERSION and only define ACPI_FADT_SPEC_VERSION as something like #define ACPI_FADT_SPEC_VERSION (((unsigned int)acpi_gbl_FADT.header.revision << 8) | (unsigned int)acpi_gbl_FADT.minor_revision) Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/