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=-3.5 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,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 B0327C2D0A3 for ; Thu, 29 Oct 2020 22:21:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 554DB20FC3 for ; Thu, 29 Oct 2020 22:21:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725864AbgJ2WVU (ORCPT ); Thu, 29 Oct 2020 18:21:20 -0400 Received: from mga07.intel.com ([134.134.136.100]:57461 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725372AbgJ2WVT (ORCPT ); Thu, 29 Oct 2020 18:21:19 -0400 IronPort-SDR: NfQkLAtSRGS/gWPoFhYjxkiWPCczqtYV5h8svMaBRW9ePxg8XKV+q1EcZ6WOuwdrYd4IL7xl3r G8zkLkv65PbA== X-IronPort-AV: E=McAfee;i="6000,8403,9789"; a="232702151" X-IronPort-AV: E=Sophos;i="5.77,431,1596524400"; d="scan'208";a="232702151" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Oct 2020 15:21:18 -0700 IronPort-SDR: CJS0rcGYr2PIy4FIbEiF05kBNSocd9wkSBPaZBQtxh7G0RWwyA0N9ef2U+BPzFH+ARO745nYJd ChYv8xYkoekw== X-IronPort-AV: E=Sophos;i="5.77,431,1596524400"; d="scan'208";a="361650059" Received: from smile.fi.intel.com (HELO smile) ([10.237.68.40]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Oct 2020 15:21:13 -0700 Received: from andy by smile with local (Exim 4.94) (envelope-from ) id 1kYGJD-001Yoh-5S; Fri, 30 Oct 2020 00:22:15 +0200 Date: Fri, 30 Oct 2020 00:22:15 +0200 From: Andy Shevchenko To: Laurent Pinchart Cc: 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: <20201029222215.GI4077@smile.fi.intel.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> <20201029212930.GE15024@pendragon.ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201029212930.GE15024@pendragon.ideasonboard.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 29, 2020 at 11:29:30PM +0200, Laurent Pinchart wrote: > 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. In this case we probably need something like struct acpi_device * acpi_dev_get_next_match_dev(struct acpi_device *adev, const char *hid, const char *uid, s64 hrv) { struct device *start = adev ? &adev->dev : NULL; ... dev = bus_find_device(&acpi_bus_type, start, &match, acpi_dev_match_cb); ... } in drivers/acpi/utils.c and static inline struct acpi_device * acpi_dev_get_first_match_dev(const char *hid, const char *uid, s64 hrv) { return acpi_dev_get_next_match_dev(NULL, hid, uid, hrv); } in include/linux/acpi.h. Then we may add #define for_each_acpi_dev_match(adev, hid, uid, hrv) \ for (adev = acpi_dev_get_first_match_dev(hid, uid, hrv); \ adev; \ adev = acpi_dev_get_next_match_dev(adev, hid, uid, hrv)) -- With Best Regards, Andy Shevchenko