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=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 21348C433E0 for ; Thu, 18 Jun 2020 16:33:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F17C2208DB for ; Thu, 18 Jun 2020 16:33:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=xs4all.nl header.i=@xs4all.nl header.b="J9LyKS1t" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729077AbgFRQdl (ORCPT ); Thu, 18 Jun 2020 12:33:41 -0400 Received: from lb2-smtp-cloud9.xs4all.net ([194.109.24.26]:36147 "EHLO lb2-smtp-cloud9.xs4all.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728523AbgFRQdk (ORCPT ); Thu, 18 Jun 2020 12:33:40 -0400 Received: from cust-b5b5937f ([IPv6:fc0c:c16d:66b8:757f:c639:739b:9d66:799d]) by smtp-cloud9.xs4all.net with ESMTPA id lxTqj4kzMOn2BlxTtjr68t; Thu, 18 Jun 2020 18:33:37 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=xs4all.nl; s=s1; t=1592498017; bh=vtKr0QJM4YQXYVakz3PAt/mbhJX5PkE3qB6K3H3yOvU=; h=Subject:To:From:Message-ID:Date:MIME-Version:Content-Type:From: Subject; b=J9LyKS1thEawyu9GhMKQvu6sYFHjlbrKeBdhchSUfggNrEZ6bowPpzF+1ez1nwKFJ qblPDJf0slg3FgDlT39zDGvichFGqDRNNi39VyT8yvRbVlKPCiuIov0VCeuXESQhCF R1q5COrVDw9So6pnifER8eRXgywxh1yyTunOGmT/TjW6rYI+fbwbGbpK93Q47LPe+f cMkFjHZ6vk6pqyzE8LmESzejpxEHNQ5geg6ZZFQnUZ7Dvysr9KqPmlUOef5V9gRMmW yRFuXGQLb3A0f4VxLHTYLebc8nm0f4I0hm4MkhOqRrouKacQqgzk+nldKS+vjPzfNU xTRxTO7zU4M2Q== Subject: Re: [PATCH v5 2/2] media: cec: i2c: ch7322: Add ch7322 CEC controller driver To: Jeff Chase Cc: linux-media@vger.kernel.org, mchehab@kernel.org, robh+dt@kernel.org, devicetree@vger.kernel.org References: <20200615193811.233737-1-jnchase@google.com> <20200615193811.233737-3-jnchase@google.com> <3aefc5c4-2af1-59f2-0797-9a5baf91482e@xs4all.nl> From: Hans Verkuil Message-ID: <72ea0f61-5fd4-47b6-4b0f-db620ee661db@xs4all.nl> Date: Thu, 18 Jun 2020 18:33:33 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-CMAE-Envelope: MS4wfEg9Fnp5dNVyyXieynelS/dpB4wvcDOi8fTMtjfdMvpYuOB89rpIizCnaS5UL6XXQTwlvKK4gwXHgHi4AP28TCQOvgjYigwr5+WnGX1VWEn2O+r8tD9W LOiv81vX0EJLHWoz0umvCou11cQnsuk4vwiBVjWD1UKkLRv1MOb17+zeBb/HvnGWDkqNLYX9Ln7/+zFLO1bmk2Ym4Rec1BMbn5+5GRkN7A+retpt4gXMEzNN EW66c9A0I9G6bMi/PA9Hit4ZMWaaaERbxHaKL9wKEMk31+5lxITmKU8C7R+cqm2iNqYBW2Kgkw6hP9ktFgxyCA== Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 18/06/2020 18:25, Jeff Chase wrote: > On Thu, Jun 18, 2020 at 3:05 AM Hans Verkuil wrote: >> >> On 18/06/2020 10:59, Jeff Chase wrote: >>> Hi Hans, >>> >>> We are using two of these in an Intel-based Chromebox. I see that the >>> cros-ec and seco drivers just statically define the PCI BDF of the >>> Intel graphics device for their boards. I don't see an example of ACPI >>> passing this information. I can copy cros-ec and seco by adding a >>> board table and then use the UID of each device to select the correct >>> port. Adding board-specific configuration to the driver doesn't seem >>> ideal but I'm not sure what the proper way to pass this using ACPI is. >> >> You are right, it's not ACPI, it's using DMI matching. >> >> I have zero knowledge about ACPI, so I have no idea if there is some standard >> method of retrieving this association via ACPI. > > I'm not very familiar with ACPI either. I looked for but did not find > an ACPI equivalent of_get_mac_address(). > > I believe it's possible to reference the PCI node but it would take a > bit of work on both the coreboot and linux side. > >> >> This particular chip can actually be used both with DMI matching but also >> on an ARM with device tree, but since you can't test this on an ARM board, >> there is no point in adding support for that. >> >> However, compared to the cros-ec and seco drivers you can do something a bit >> different here: those drivers just return -ENODEV if there is no match, but >> since this driver reads the EDID it can just continue as long as it does not >> set the CEC_CAP_CONNECTOR_INFO capability. > > Is it necessary to add support if we don't set CEC_CAP_CONNECTOR_INFO? It is very desirable. Otherwise userspace will not know which CEC device is associated with which HDMI device. Since you are using two of these chips for a Chromebox, I suspect that you actually need to support this. Also, I am (slowly) working on wiring support for this in all CEC transmitter drivers, so I prefer not to add CEC drivers without support for this. I really should have noticed much earlier that support for this was missing. My apologies for that. Regards, Hans