Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964901AbbBDJvc (ORCPT ); Wed, 4 Feb 2015 04:51:32 -0500 Received: from mail-oi0-f42.google.com ([209.85.218.42]:60188 "EHLO mail-oi0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933680AbbBDJv2 (ORCPT ); Wed, 4 Feb 2015 04:51:28 -0500 MIME-Version: 1.0 In-Reply-To: <2116821.DVmvasqCz1@vostro.rjw.lan> References: <1418890998-23811-1-git-send-email-heikki.krogerus@linux.intel.com> <4006695.qV8Mor20ru@vostro.rjw.lan> <2116821.DVmvasqCz1@vostro.rjw.lan> Date: Wed, 4 Feb 2015 10:51:27 +0100 Message-ID: Subject: Re: [RFC PATCH] gpio: support for GPIO forwarding From: Linus Walleij To: "Rafael J. Wysocki" Cc: Alexandre Courbot , Heikki Krogerus , "Rafael J. Wysocki" , Darren Hart , Arnd Bergmann , Andy Shevchenko , Mika Westerberg , "linux-gpio@vger.kernel.org" , "linux-kernel@vger.kernel.org" , ACPI Devel Maling List 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: 2073 Lines: 44 On Fri, Jan 30, 2015 at 5:17 PM, Rafael J. Wysocki wrote: > On Friday, January 30, 2015 03:48:30 PM Linus Walleij wrote: >> So you could detect one by making a checksum of the binary or something. >> >> And then you'd know that the table with this checksum needs patching? > > At a single table level it is generally difficult to say whether or not > things are going to work. > > What needs to work is the namespace which is built from all of the tables > provided combined. So the namespace needs to be populated first and then > fixes applied on top of that (presumably by deleting, adding or replacing > objects). > > Now, in theory, you *may* be able to figure out that combination of tables > A produces namespace B which then will require fix X if the system is Y, > but quite frankly I wouldn't count on that. > > Moreover, fixups (or "patches" as I called them, but that wasn't exactly > correct) need to be provided in the form of AML definition blocks to apply on > top of an already populated namespace and if you want to use a binary kernel image, > you can't really afford putting all that stuff for all systems it can possibly > run on into it. This means that distros need to be able to combine a fixup for > the ACPI tables with the binary kernel and install the result into the system's > boot medium (whatever it is). Also it should be possible to update the fixup > and the kernel image separately if necessary. > > Now from the kernel's perspective that raises the question: "What if the > ACPI tables fixup provided by the distro is not sufficient?" > > That needs to be addressed somehow in the code. Yeah I guess I'm convinced that we need to handle this particular weirdness in the gpio-acpi code... if it can be contained there as expressed by Alexandre. Yours, Linus Walleij -- 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/