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 3D271C5519F for ; Mon, 16 Nov 2020 14:11:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CCFD7222E8 for ; Mon, 16 Nov 2020 14:11:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="SEdfL+vN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729397AbgKPOKq (ORCPT ); Mon, 16 Nov 2020 09:10:46 -0500 Received: from perceval.ideasonboard.com ([213.167.242.64]:48864 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727260AbgKPOKp (ORCPT ); Mon, 16 Nov 2020 09:10:45 -0500 Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id B6D0DA1B; Mon, 16 Nov 2020 15:10:42 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1605535843; bh=p0A0S6847SnNmvv85Vpj6XHcSbbIsP2+YZ/YS1m3Udc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SEdfL+vNG1UcIpa2XZOggHNtOgqcyFkFz3dqFVu7GIiZ8HXnQLRxSQbVEVuC0lzzx uwnIZy0L3t9CB8IQEigKgRtEznsEZ/+zviu/rGyrmPIX0UBNRDjbiRmbOooFK+zn9i UJpi53l/Tx/7kqtHS+KDb1TpS3JrLamYvcYohifA= Date: Mon, 16 Nov 2020 16:10:38 +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: <20201116141038.GJ6540@pendragon.ideasonboard.com> References: <20201029201918.GD15024@pendragon.ideasonboard.com> <20201029212930.GE15024@pendragon.ideasonboard.com> <20201029222215.GI4077@smile.fi.intel.com> <20201029225124.GI15024@pendragon.ideasonboard.com> <60b36af2-ad57-000b-76e4-379e1b58a3a0@gmail.com> <20201113162231.GO7524@pendragon.ideasonboard.com> <20201116085349.GA6540@pendragon.ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Andy, On Mon, Nov 16, 2020 at 03:57:17PM +0200, Andy Shevchenko wrote: > On Mon, Nov 16, 2020 at 10:53 AM Laurent Pinchart wrote: > > On Fri, Nov 13, 2020 at 09:45:00PM +0200, Andy Shevchenko wrote: > > > On Fri, Nov 13, 2020 at 6:22 PM Laurent Pinchart wrote: > > > > On Fri, Nov 13, 2020 at 10:02:30AM +0000, Dan Scally wrote: > > > > > On 29/10/2020 22:51, Laurent Pinchart wrote: > > > > > > On Fri, Oct 30, 2020 at 12:22:15AM +0200, Andy Shevchenko wrote: > > > > > >> On Thu, Oct 29, 2020 at 11:29:30PM +0200, Laurent Pinchart wrote: > > > > > > ... > > > > > > > > >> 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)) > > > > > > > > > > > > What the cio2-bridge code needs is indeed > > > > > > > > > > > > for each hid in supported hids: > > > > > > for each acpi device that is compatible with hid: > > > > > > ... > > > > > > > > > > > > which could also be expressed as > > > > > > > > > > > > for each acpi device: > > > > > > if acpi device hid is in supported hids: > > > > > > ... > > > > > > > > > > > > I don't mind either option, I'll happily follow the preference of the > > > > > > ACPI maintainers. > > > > > > > > > > Does this need raising elsewhere then? The original idea of just > > > > > bus_for_each_dev(&acpi_bus_type...) I have now tested and it works fine, > > > > > but it does mean that I need to export acpi_bus_type (currently that > > > > > symbol's not available)...that seems much simpler to me but I'm not sure > > > > > whether that's something to avoid, and if so whether Andy's approach is > > > > > better. > > > > > > > > > > Thoughts? > > > > > > > > I like simple options :-) A patch to export acpi_bus_type, with enough > > > > context in the commit message (and in the cover latter of the series), > > > > should be enough to provide all the information the ACPI maintainers > > > > need to decide which option is best. With a bit of luck that patch will > > > > be considered the best option and no extra work will be needed. > > > > > > The problem with ACPI bus is that it is not as simple as other buses, > > > i.e. it may have purely ACPI devices along with *companion* devices, > > > which are usually represented by platform bus. On top of that for > > > several ACPI devices there can be one physical node and it will be not > > > so clear what you are exactly looking for by traversing acpi_bus_type. > > > I believe it's hidden on purpose. > > > > Maybe there's something I don't get, as I'm not very familiar with the > > ACPI implementation in the kernel, but the code in the cio2-bridge, > > unless I'm mistaken, is really interested in ACPI devices on the ACPI > > bus, not companions or other devices related to the ACPI devices. > > AFAICS cio2-bridge wants to find ACPI companion devices which are > enumerated as platform ones (or I²C or SPI). I thought we were looking for ACPI devices, not companion devices, in order to extract information from the DSDT and store it in a software node. I could very well be wrong though. > > The > > iterators you have proposed above use bus_find_device() on > > acpi_bus_type, so I don't really see how they make a difference from a > > cio2-bridge point of view. > > This seems to be true. The iterators have no means to distinguish > between companion devices and pure ACPI, for example. > For this one needs to call something like 'get first physical node' > followed by 'let's check that it has a companion and that the one we > have already got from ACPI bus iterator'. > > > Is your point that acpi_bus_type shouldn't be > > exported because it could then be misused by *other* drivers ? Couldn't > > those drivers then equally misuse the iterators ? > > My point is that the ACPI bus type here is not homogenous. > And thus I think it was the reason behind hiding it. I might be > mistaken and you may ask ACPI maintainers for the clarification. > > In summary I think we are trying to solve a problem that has not yet > existed (devices with several same sensors). Do we have a DSDT of such > to look into? Not to my knowledge. -- Regards, Laurent Pinchart