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 X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9CB35C4741F for ; Thu, 29 Oct 2020 21:30:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2608B20FC3 for ; Thu, 29 Oct 2020 21:30:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="jLSaTz9M" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726681AbgJ2VaX (ORCPT ); Thu, 29 Oct 2020 17:30:23 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:44904 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726618AbgJ2VaW (ORCPT ); Thu, 29 Oct 2020 17:30:22 -0400 Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 2E59350E; Thu, 29 Oct 2020 22:30:19 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1604007019; bh=JupRYDrACxZi2dan1zmzzAPEpNGLOP2kl4V8Z1CAl1Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jLSaTz9MGLOBsTGSgTKiRzQNQQ4raRNFsKtoqW/1yeFhXvxfnA9rvNdeXCp6M8LP+ NpVU8ck4UqME9y+0YNdFpqlIjSdEUSd7vhAqy/a1I6uf30CQT9LJPIwQwZCZZt1tZp EmbVy2GHNqS/UeY3fB/iFYsyhwRuJL3HcGAQBC7o= Date: Thu, 29 Oct 2020 23:29:30 +0200 From: Laurent Pinchart To: Andy Shevchenko Cc: Andy Shevchenko , Dan Scally , Linux Kernel Mailing List , Linux Media Mailing List , Linus Walleij , prabhakar.mahadev-lad.rj@bp.renesas.com, "Krogerus, Heikki" , Dmitry Torokhov , laurent.pinchart+renesas@ideasonboard.com, kieran.bingham+renesas@ideasonboard.com, Jacopo Mondi , Rob Herring , "David S. Miller" , Rasmus Villemoes , Sergey Senozhatsky , Steven Rostedt , Petr Mladek , Mauro Carvalho Chehab , Tian Shu Qiu , Bingbu Cao , Sakari Ailus , Yong Zhi , "Rafael J. Wysocki" , Greg Kroah-Hartman , Tsuchiya Yuto Subject: Re: [RFC PATCH v3 9/9] ipu3-cio2: Add functionality allowing software_node connections to sensors on platforms designed for Windows Message-ID: <20201029212930.GE15024@pendragon.ideasonboard.com> References: <20201019225903.14276-1-djrscally@gmail.com> <20201019225903.14276-10-djrscally@gmail.com> <20201024012411.GT5979@pendragon.ideasonboard.com> <20201024093702.GA3939@pendragon.ideasonboard.com> <20201026161050.GQ4077@smile.fi.intel.com> <20201029201918.GD15024@pendragon.ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On Thu, Oct 29, 2020 at 10:26:56PM +0200, Andy Shevchenko wrote: > On Thu, Oct 29, 2020 at 10:21 PM Laurent Pinchart wrote: > > On Mon, Oct 26, 2020 at 06:10:50PM +0200, Andy Shevchenko wrote: > > > On Sat, Oct 24, 2020 at 12:37:02PM +0300, Laurent Pinchart wrote: > > > > On Sat, Oct 24, 2020 at 09:50:07AM +0100, Dan Scally wrote: > > > > > On 24/10/2020 02:24, Laurent Pinchart wrote: > > > > > > On Mon, Oct 19, 2020 at 11:59:03PM +0100, Daniel Scally wrote: > > > > > > > > >> + adev = acpi_dev_get_first_match_dev(supported_devices[i], NULL, -1); > > > > > > > > > > > > What if there are multiple sensor of the same model ? > > > > > > > > > > Hmm, yeah, that would be a bit of a pickle. I guess the newer > > > > > smartphones have multiple sensors on the back, which I presume are the > > > > > same model. So that will probably crop up at some point. How about > > > > > instead I use bus_for_each_dev() and in the applied function check if > > > > > the _HID is in the supported list? > > > > > > > > Sounds good to me. > > > > > > > > > >> + if (!adev) > > > > > >> + continue; > > > > > > Please, don't. > > > > > > If we have so weird ACPI tables it must be w/a differently. The all, even badly > > > formed, ACPI tables I have seen so far are using _UID to distinguish instance > > > of the device (see second parameter to the above function). > > > > > > If we meet the very broken table I would like rather to know about, then > > > silently think ahead what could be best. > > > > > > I.o.w. don't change this until we will have a real example of the problematic > > > firmware. > > > > I'm not sure to follow you. Daniel's current code loops over all the > > supported HID (as stored in the supported_devices table), and then gets > > the first ACPI device for each of them. If multiple ACPI devices exist > > with the same HID, we need to handle them all, so enumerating all ACPI > > devices and checking whether their HID is one we handle seems to be the > > right option to me. > > Devices with the same HID should be still different by another > parameter in ACPI. The above mentioned call just uses the rough > estimation for relaxed conditions. If you expect more than one device > with the same HID how do you expect to distinguish them? The correct > way is to use _UID. It may be absent, or set to a value. And this > value should be unique (as per U letter in UID abbreviation). That > said, the above is good enough till we find the firmware with the > above true (several devices with the same HID). Until then the code is > fine. I expect those devices with the same _HID to have different _UID values, yes. On the systems I've seen so far, that assumption is not violated, and I don't think we need to already plan how we will support systems where multiple devices would have the same _HID and _UID (within the same scope). There's no disagreement there. My point is that supported_devices stores HID values, and doesn't care about UID. The code loops over supported_devices, and for each entry, calls acpi_dev_get_first_match_dev() and process the ACPI devices returned by that call. We thus process at most one ACPI device per HID, which isn't right. -- Regards, Laurent Pinchart