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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_MUTT autolearn=ham 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 520C1C48BD5 for ; Tue, 25 Jun 2019 14:08:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 24CD7208E3 for ; Tue, 25 Jun 2019 14:08:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="DlsNVgfR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728738AbfFYOIB (ORCPT ); Tue, 25 Jun 2019 10:08:01 -0400 Received: from mail-ed1-f66.google.com ([209.85.208.66]:34017 "EHLO mail-ed1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727807AbfFYOIA (ORCPT ); Tue, 25 Jun 2019 10:08:00 -0400 Received: by mail-ed1-f66.google.com with SMTP id s49so27399313edb.1 for ; Tue, 25 Jun 2019 07:07:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=sender:date:from:to:cc:subject:message-id:mail-followup-to :references:mime-version:content-disposition :content-transfer-encoding:in-reply-to:user-agent; bh=CAtg3PLJ+XKSV8dAF2QLAFWrkpUis1quRM8X3SddO/c=; b=DlsNVgfRWTP8NpGGrX9t3Nbz1zo7ltZhwtKOk/Es+ZdbHwht+lr3TCIe70hcYOlrBR ABPEEparLAqoeRRvZ5Pzq1cEVMTiKJ3tiqSO4M7ZzKp6aqKBOmxw686MYovwaEFXhy8l NK+f1Jf6pSuG3cXFg7wdY+FYcdimxOYB8sVXQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :mail-followup-to:references:mime-version:content-disposition :content-transfer-encoding:in-reply-to:user-agent; bh=CAtg3PLJ+XKSV8dAF2QLAFWrkpUis1quRM8X3SddO/c=; b=lkPpjKtioO7WS6HhRJnMr6zwQ6fUIct6hASneSRMbWWhMsGe93sK0mWpY2vqzqR6eX WDtu3MrKGwZtpu1Z/HBWqNyWP0etqt3hpFN6L0fSoORC8cROGE8iQXsqOQRR1AKlLQzd PTfNcpXUu6LzMJMy+YqDG69Y2xkMFCsp8+XvaY9osM2uG+UAte723tivk0Neo1If8pbD Way7aS7SWzWs1s8eTQzzgzicjvZLwBSxlAlfegFR6KCDtDxSDkHvuOJL6wkI+xhRUNvH aao4KaaDvhXa8N/KBOj/1MrJP2Ke1g/i33ihxB9orvZj6dGMTMAdf/y7EF5aISkeDGzy kS/A== X-Gm-Message-State: APjAAAV4lmPxxoKg2ZsaBlxbwQXX0uBNGdkJWyxbl0Hb2/n5GqLG6oMW a8veBIqci7VMmYjXQzxJYu6ntA== X-Google-Smtp-Source: APXvYqwnUNvO8RCgD+CoeE0AtlUeuwzv5wVl2MiDkEcmAY2cVmivLFNLtUKUMk2lZa5wxlyqXHk8gw== X-Received: by 2002:a50:92e1:: with SMTP id l30mr77999218eda.141.1561471678547; Tue, 25 Jun 2019 07:07:58 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:569e:0:3106:d637:d723:e855]) by smtp.gmail.com with ESMTPSA id w17sm4594091edi.15.2019.06.25.07.07.56 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 25 Jun 2019 07:07:57 -0700 (PDT) Date: Tue, 25 Jun 2019 16:07:55 +0200 From: Daniel Vetter To: Emil Velikov Cc: Andrzej Pietrasiewicz , Russell King - ARM Linux admin , linux-samsung-soc@vger.kernel.org, Joonyoung Shim , Maxime Ripard , Seung-Woo Kim , Maarten Lankhorst , linux-kernel@vger.kernel.org, Krzysztof Kozlowski , Inki Dae , David Airlie , Kyungmin Park , Kukjin Kim , dri-devel@lists.freedesktop.org, Daniel Vetter , kernel@collabora.com, Sean Paul , linux-arm-kernel@lists.infradead.org, m.szyprowski@samsung.com Subject: Re: [PATCH 0/2] Associate ddc adapters with connectors Message-ID: <20190625140755.GT12905@phenom.ffwll.local> Mail-Followup-To: Emil Velikov , Andrzej Pietrasiewicz , Russell King - ARM Linux admin , linux-samsung-soc@vger.kernel.org, Joonyoung Shim , Maxime Ripard , Seung-Woo Kim , Maarten Lankhorst , linux-kernel@vger.kernel.org, Krzysztof Kozlowski , Inki Dae , David Airlie , Kyungmin Park , Kukjin Kim , dri-devel@lists.freedesktop.org, kernel@collabora.com, Sean Paul , linux-arm-kernel@lists.infradead.org, m.szyprowski@samsung.com References: <20190625100351.52ddptvb2gizaepi@shell.armlinux.org.uk> <817ccfba-754c-6a28-8d75-63f70605fd43@collabora.com> <20190625133639.GA16031@arch-x1c3> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190625133639.GA16031@arch-x1c3> X-Operating-System: Linux phenom 4.19.0-5-amd64 User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 25, 2019 at 02:36:39PM +0100, Emil Velikov wrote: > On 2019/06/25, Andrzej Pietrasiewicz wrote: > > Hi Russell, > > > > W dniu 25.06.2019 o 12:03, Russell King - ARM Linux admin pisze: > > > On Tue, Jun 25, 2019 at 11:46:34AM +0200, Andrzej Pietrasiewicz wrote: > > > > It is difficult for a user to know which of the i2c adapters is for which > > > > drm connector. This series addresses this problem. > > > > > > > > The idea is to have a symbolic link in connector's sysfs directory, e.g.: > > > > > > > > ls -l /sys/class/drm/card0-HDMI-A-1/i2c-2 > > > > lrwxrwxrwx 1 root root 0 Jun 24 10:42 /sys/class/drm/card0-HDMI-A-1/i2c-2 \ > > > > -> ../../../../soc/13880000.i2c/i2c-2 > > > > > > Don't you want the symlink name to be "i2c" or something fixed, rather > > > than the name of the i2c adapter? Otherwise, you seem to be encumbering > > > userspace with searching the directory to try and find the symlink. > > > > > > > Thank you for your comment. So you imagine something on the lines of: > > > > lrwxrwxrwx 1 root root 0 Jun 24 10:42 /sys/class/drm/card0-HDMI-A-1/ddc \ > > -> ../../../../soc/13880000.i2c/i2c-2 > > > > ? > > > Fwiw my Intel machine lists a number of i2c devices: > /sys/class/drm/card0-DP-1/i2c-6 > /sys/class/drm/card0-DP-2/i2c-7 > /sys/class/drm/card0-eDP-1/i2c-5 > > Note: I haven't looked _if_ they relate to ones you're proposing here. > > One thing worth mentioning is, the ones I've seen are not symlinks to > another sysfs entries. And there aren't any i2c nodes in /dev ... > > Just a random food for thought :-) Those are the i2c-over-dp-aux controllers. I think we want to list these too. Btw to make this more useful maybe some default implementations for get_modes which automatically dtrt, as a helper? Probably could use that to squash quite a bit of boilerplate. Otherwise I like this. Biggest problem I'm seeing here is rolling this out everywhere, this is a lot of work. And without widespread adoptions it's not terribly useful for userspace. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch