From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6CD16C64ED6 for ; Wed, 22 Feb 2023 19:11:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232415AbjBVTLO (ORCPT ); Wed, 22 Feb 2023 14:11:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45428 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230402AbjBVTLN (ORCPT ); Wed, 22 Feb 2023 14:11:13 -0500 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D36B938B59; Wed, 22 Feb 2023 11:11:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1677093071; x=1708629071; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=X4wQ+O3eBVoGDjrrVinp2PRl4OgU1Fc491UedwVGnKs=; b=Qo46ycor//CApUGO0xcuccJo0vbrzwW4gvMugdUkZLOCa9uj5s38uQin 1++FKtO7b4wrxUJLCYCPHINdh8kVnMwOCTXI5pDLhYIkwoHlwMUzwdnJ2 23LWmO3x3m5qfLwFlydGExHD04raySoHIkyxbwSl3QZ1A2NpqwWMh1PD6 RhqwGO0DAXEdvz6+JC7E+mP539LqzugJbGPsi/IQcqSJVCypYcFKRk1md qj/c5hwPV137ifBASsGfHHbUDpma5WWyyRD/kBmEgIEpEo9/0l36Gsv5p NI1OG4i/hbxoayVFQXwU2MrjSRCFXXWbPdMs5BksCOPcMRbDNL/f6Djyr w==; X-IronPort-AV: E=McAfee;i="6500,9779,10629"; a="333022472" X-IronPort-AV: E=Sophos;i="5.97,319,1669104000"; d="scan'208";a="333022472" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Feb 2023 11:11:11 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10629"; a="761058560" X-IronPort-AV: E=Sophos;i="5.97,319,1669104000"; d="scan'208";a="761058560" Received: from smile.fi.intel.com ([10.237.72.54]) by FMSMGA003.fm.intel.com with ESMTP; 22 Feb 2023 11:11:08 -0800 Received: from andy by smile.fi.intel.com with local (Exim 4.96) (envelope-from ) id 1pUuW9-00AaOx-30; Wed, 22 Feb 2023 21:11:05 +0200 Date: Wed, 22 Feb 2023 21:11:05 +0200 From: Andy Shevchenko To: Krzysztof Kozlowski Cc: Robin van der Gracht , Rob Herring , Krzysztof Kozlowski , "Russell King (Oracle)" , Raul E Rangel , Wolfram Sang , linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org, linux-usb@vger.kernel.org, Miguel Ojeda , Heikki Krogerus , Greg Kroah-Hartman , devicetree@vger.kernel.org Subject: Re: [PATCH v1 2/3] auxdisplay: ht16k33: Make use of device_get_match_data() Message-ID: References: <20230221133307.20287-1-andriy.shevchenko@linux.intel.com> <20230221133307.20287-3-andriy.shevchenko@linux.intel.com> <0235f0fed989a8b027db720663699f5d@protonic.nl> <06f29d66-f16a-039c-ecd0-155bdcce00c1@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <06f29d66-f16a-039c-ecd0-155bdcce00c1@linaro.org> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Wed, Feb 22, 2023 at 07:46:25PM +0100, Krzysztof Kozlowski wrote: > On 22/02/2023 18:20, Andy Shevchenko wrote: > >> > >>> Which effectively breaks i.e. user-space instantiation for other display > >>> types which now do work due to i2c_of_match_device(). > >>> (so my suggestion above is not sufficient). > >>> > >>> Are you proposing extending and searching the I2C ID table to work around > >>> that? > >> > >> See (1) above. This is the downside I have noticed after sending this series. > >> So, the I²C ID table match has to be restored, but the above mentioned issues > >> with existing table are not gone, hence they need to be addressed in the next > >> version. > > > > I see now what you mean. So, we have even more issues in this driver: > > - I²C table is not in sync with all devices supported > > Does anything actually rely on i2c_device_id table? ACPI would match > either via ACPI or OF tables. All modern ARM systems (e.g. imx6) are > DT-based. Maybe just drop the I2C ID table? For I²C it's still possible to enumerate the device via sysfs, which is ABI. > > - the OF ID table seems has something really badly formed for adafruit > > (just a number after a comma) > > Maybe it is a model number? It was documented: > Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml Yes, it's not a problem for ACPI/DT platforms, the problem is for the above way of enumeration, so if we have more than 1 manufacturer that uses plain numbers for the model, I²C framework may not distinguish which driver to use. I.o.w. the part after comma in the compatible strings of the I²C devices must be unique globally to make that enumeration disambiguous. > > The latter shows how broken it is. The I²C ID table mechanism is used as > > a backward compatibility to the OF. Unfortunately, user space may not provide > > the data except in form of DT overlays, so for the legacy enumeration we > > have only device name, which is a set of 4 digits for adafruit case. > > > > Now imagine if by some reason we will get adafruit2 (you name it) with > > the same schema. How I²C framework can understand that you meant adafruit > > and not adafruit2? Or did I miss something? -- With Best Regards, Andy Shevchenko