From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754791AbaHBMkL (ORCPT ); Sat, 2 Aug 2014 08:40:11 -0400 Received: from mail-wg0-f47.google.com ([74.125.82.47]:36889 "EHLO mail-wg0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751534AbaHBMkI (ORCPT ); Sat, 2 Aug 2014 08:40:08 -0400 Message-ID: <53DCDC23.1090105@gmail.com> Date: Sat, 02 Aug 2014 14:40:03 +0200 From: Tomasz Figa User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 MIME-Version: 1.0 To: =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= , linux-samsung-soc@vger.kernel.org CC: linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, Stephan van Schaik , Vincent Palatin , Doug Anderson , Javier Martinez Canillas , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Russell King , Ben Dooks , Kukjin Kim , open list Subject: Re: [PATCH v4 4/4] ARM: dts: Add exynos5250-spring device tree References: <1406822910-6255-1-git-send-email-afaerber@suse.de> <1406822910-6255-5-git-send-email-afaerber@suse.de> <53DA936E.9060004@gmail.com> <53DB06D6.9060604@suse.de> In-Reply-To: <53DB06D6.9060604@suse.de> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01.08.2014 05:17, Andreas Färber wrote: > Am 31.07.2014 21:05, schrieb Tomasz Figa: >>> + >>> +&i2c_2 { >>> + status = "okay"; >>> + samsung,i2c-sda-delay = <100>; >>> + samsung,i2c-max-bus-freq = <66000>; >>> + >>> + hdmiddc@50 { >>> + compatible = "samsung,exynos4210-hdmiddc"; >>> + reg = <0x50>; >>> + }; >> >> I don't think this matches current Exynos HDMI bindings, which I believe >> have been changed to just take a phandle to i2c bus instead. > > Looks correct to me: > > http://git.kernel.org/cgit/linux/kernel/git/kgene/linux-samsung.git/tree/Documentation/devicetree/bindings/video/exynos_hdmiddc.txt?h=for-next > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/tree/Documentation/devicetree/bindings/video/exynos_hdmiddc.txt Looks correct according to the documentation, but unfortunately this is not the first time (and most likely not the last time) when our Exynos DRM people carelessly change the binding without taking care of updating relevant documentation correctly... Please see following code: https://git.kernel.org/cgit/linux/kernel/git/daeinki/drm-exynos.git/tree/drivers/gpu/drm/exynos/exynos_hdmi.c?h=exynos-drm-next#n2415 To get the DDC I2C adapter it first tries to look by a hardcoded compatible string for backwards compatibility, but when there is no such node, it uses the "ddc" property which is a phandle to the I2C adapter node on which the DDC channel will be present. Long story short, the binding of fake DDC device is obsolete and should be marked so in documentation, while new device trees should only use the new way with phandle. However what this patch adds is for now technically correct and should work even if support for old bindings is dropped in future, so I won't consider this an issue. Best regards, Tomasz