From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751840Ab2KPNnP (ORCPT ); Fri, 16 Nov 2012 08:43:15 -0500 Received: from zoneX.GCU-Squad.org ([194.213.125.0]:14939 "EHLO services.gcu-squad.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751771Ab2KPNnO (ORCPT ); Fri, 16 Nov 2012 08:43:14 -0500 Date: Fri, 16 Nov 2012 14:42:56 +0100 From: Jean Delvare To: "Rafael J. Wysocki" Cc: Mika Westerberg , ben-linux@fluff.org, w.sang@pengutronix.de, linux-kernel@vger.kernel.org, lenb@kernel.org, rafael.j.wysocki@intel.com, broonie@opensource.wolfsonmicro.com, grant.likely@secretlab.ca, linus.walleij@linaro.org, bhelgaas@google.com, mathias.nyman@linux.intel.com, linux-acpi@vger.kernel.org Subject: Re: [PATCH v2 3/3] i2c / ACPI: add ACPI enumeration support Message-ID: <20121116144256.55b49cae@endymion.delvare> In-Reply-To: <1499062.QDd9DGofy9@vostro.rjw.lan> References: <1352977397-2280-1-git-send-email-mika.westerberg@linux.intel.com> <2439178.tCj2rUMYJS@vostro.rjw.lan> <20121116140357.5e0a6d6b@endymion.delvare> <1499062.QDd9DGofy9@vostro.rjw.lan> X-Mailer: Claws Mail 3.7.10 (GTK+ 2.24.7; x86_64-suse-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 16 Nov 2012 14:21:54 +0100, Rafael J. Wysocki wrote: > On Friday, November 16, 2012 02:03:57 PM Jean Delvare wrote: > > Hi Rafael, > > > > On Fri, 16 Nov 2012 11:09:03 +0100, Rafael J. Wysocki wrote: > > > On Thursday, November 15, 2012 01:03:17 PM Mika Westerberg wrote: > > > > ACPI 5 introduced I2cSerialBus resource that makes it possible to enumerate > > > > and configure the I2C slave devices behind the I2C controller. This patch > > > > adds helper functions to support I2C slave enumeration. > > > > > > > > An ACPI enabled I2C controller driver only needs to call acpi_i2c_register_devices() > > > > in order to get its slave devices enumerated, created and bound to the > > > > corresponding ACPI handle. > > > > > > > > Signed-off-by: Mika Westerberg > > > > > > Are there any objections against this patch or comments? > > > > > > Worfram? Jean? Ben? > > > > I am no longer maintaining the i2c subsystem and will not have the time > > to look deeply into this. All I can say is that I very happy to see > > this finally happen. Maybe with ACPI 5.0 we will finally be done with > > resource conflicts plaguing many systems for several years now. > > > > I took a quick look, and the only thing which seems suspicious is this > > function: > > > > > +static int acpi_i2c_find_child_address(struct acpi_resource *ares, void *data) > > > +{ > > > + struct acpi_resource_i2c_serialbus *sb; > > > + struct acpi_i2c_find *i2c_find = data; > > > + > > > + if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS) > > > + return 1; > > > + > > > + sb = &ares->data.i2c_serial_bus; > > > + if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C) > > > + return 1; > > > + > > > + if (sb->slave_address == i2c_find->addr) > > > > The 7-bit and 10-bit address maps overlap, so the above isn't enough. > > You must compare the addresses _and_ sb->access_mode with > > i2c_find->access_mode (which needs to be added and filled properly.) > > > > > + i2c_find->found = true; > > > + > > > + return 1; > > > +} > > > > Plus, it seems odd that this function always returns 1. > > Yes, this is a bug I think. Mika? The equivalent function for SPI devices does the same, so if this is a bug, it must be fixed there too. If this is not a bug then it is questionable why these functions return something in the first place. But then again I didn't look into the design, so I may be missing something. -- Jean Delvare