Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753222AbbETJjv (ORCPT ); Wed, 20 May 2015 05:39:51 -0400 Received: from mail-wg0-f49.google.com ([74.125.82.49]:33209 "EHLO mail-wg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753029AbbETJjo (ORCPT ); Wed, 20 May 2015 05:39:44 -0400 MIME-Version: 1.0 In-Reply-To: <20150520074708.GQ1490@lahna.fi.intel.com> References: <1432044209-27858-1-git-send-email-robert.dolca@intel.com> <20150520074708.GQ1490@lahna.fi.intel.com> From: Robert Dolca Date: Wed, 20 May 2015 12:39:22 +0300 Message-ID: Subject: Re: [PATCH RFC] i2c: Use ID table to detect ACPI I2C devices To: Mika Westerberg Cc: Robert Dolca , linux-i2c@vger.kernel.org, linux-acpi@vger.kernel.org, "linux-kernel@vger.kernel.org" , Wolfram Sang , "Rafael J. Wysocki" , Len Brown , Daniel Baluta 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: 2056 Lines: 48 On Wed, May 20, 2015 at 10:47 AM, Mika Westerberg wrote: > On Tue, May 19, 2015 at 05:03:29PM +0300, Robert Dolca wrote: >> For i2c devices enumerated with ACPI you need to declare both >> acpi_match_table and id_table. When using ACPI, the i2c_device_id structure >> supplied to the probe function is null and you have to handle this case >> in the driver. >> >> The current name for the i2c client when using ACPI is "HID:UID" where the >> UID has 7 or 8 characters and the UID has 2 characters. The UID is not >> relevant for identifying the chip so it does not have any practical >> purpose. > > First of all, it is not "HID:UID" since the number after ":" is actually > increasing number assigned by the ACPI core. Nothing to do with _UID. You are right. My mistake. > Secondly we do not list "_HID:nn" in drivers acpi_match_tables but > instead it is either "HID" or "CID", no ":nn" there. I didn't say that you do that :) > >> Modifying i2c_match_id we make the comparison by ignoring the UID from the >> client name when the device was discovered using ACPI. The comparison is >> case insensitive because the ACPI names are uppercase and the DT and ID >> table names are lowercase. It would not make sense to have two different >> chips with the same name and the only diference being the capitalized >> letters. >> >> With these changes the probe function gets a valid i2c_device_id and the >> driver doesn't have to declare acpi_match_table. > > No. We don't do that for DT and we definitely don't want to mix ACPI > identifiers with arbitrary I2C device names. > > You are not supposed to put ACPI identifiers into i2c_device_id table. Currently, if the name used for DT (in dts) matches one of the names specified in the id table you will have a match. Isn't that an intended behavior? Robert -- 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/