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=-15.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 CE9CAC433ED for ; Tue, 20 Apr 2021 15:19:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9982B613C9 for ; Tue, 20 Apr 2021 15:19:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232823AbhDTPU1 (ORCPT ); Tue, 20 Apr 2021 11:20:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34414 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232303AbhDTPU0 (ORCPT ); Tue, 20 Apr 2021 11:20:26 -0400 Received: from mail-wr1-x433.google.com (mail-wr1-x433.google.com [IPv6:2a00:1450:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 23238C06174A for ; Tue, 20 Apr 2021 08:19:55 -0700 (PDT) Received: by mail-wr1-x433.google.com with SMTP id x7so37991996wrw.10 for ; Tue, 20 Apr 2021 08:19:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=baylibre-com.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:organization:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=22YXfrzIvJI/e0g2j0aYDyGRkNGq51wKgMJOLCS1QVw=; b=O61+oMWcADefXaQH2XclZbsr8Gd7B9uLWxTfxX0HtcSO9lbF4+LkcGS0iIhDDh61be Z8oPcqd/CUqGkbr9KwpjSNpjMGm9Xc9TriI8pehb0SW2S0TRqn7erkeJjTFBS4cJlqxK pNcKkTRE71jn+HJrb/nPm0hoGEYJCLsuAiHH/YaP+MkVtO3NIaBt7M7c9eHfnGImLqMt Czv9TFOQgwdHlwcGkvbyaQfCPC0PDwBZ3Rb1aB7i8jO+QreDfqaM/DyI3kEtduKOeWfL AYh174xTlv8ExB69UMRkOBXLMhtyswnGm4rADX5Tlo9naPUH15Taa8l1N2KngHJMV5px R4ZQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:organization :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=22YXfrzIvJI/e0g2j0aYDyGRkNGq51wKgMJOLCS1QVw=; b=JrTolzZFsUC2164GupqLE8wJzoMMG7EPFFB/F+a4j2YrC5gW7LFOh63+RC1FfIWmaj mWqPwELy282Uioydvtnu9UsRJJDmsO5dSH2kYnQo0J/BKelJx/GyH6w5qbP1D6kD5gXR Rx2L3bwOYWfAiqQD8D3ltWOJIxEwnvwqwwb1RckTvZUMYu3RhHvA+02sZ1skbM3GCqJI dB2BmxmkD/1lIwJOtEHg52AEoqya73/l4idaQdu2+8Ll7yRtikq+u36sI2FlASfquKjp Ej7t1aBg5IPC1soyo4zbWpohxizUhHYRal3jhuzVot5JXUNeJJ2YvHAIYdKjiZlnCCVh 7ihw== X-Gm-Message-State: AOAM530hD0dhC1YjDAlSpWhWvou/s/Ds+pzbwIqLrFaoJX9dTa550EQu EAYcaaegH3f1eeroHDClxG5k+UGLnOvBzsor X-Google-Smtp-Source: ABdhPJyYBtbYLuNyS+ppFk55wLeiEgofP4BmVUU7O9xG8j+pYW7WvxoWIH4KP4AuNd0cwIk7oMLsug== X-Received: by 2002:a05:6000:178c:: with SMTP id e12mr21440298wrg.42.1618931993723; Tue, 20 Apr 2021 08:19:53 -0700 (PDT) Received: from ?IPv6:2a01:e0a:90c:e290:b4:316d:263e:1360? ([2a01:e0a:90c:e290:b4:316d:263e:1360]) by smtp.gmail.com with ESMTPSA id h10sm13764777wrt.40.2021.04.20.08.19.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 20 Apr 2021 08:19:53 -0700 (PDT) Subject: Re: [PATCH 0/2] drm/bridge: dw-hdmi: disable loading of DW-HDMI CEC sub-driver To: Hans Verkuil , Laurent Pinchart Cc: jernej.skrabec@siol.net, jonas@kwiboo.se, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, robert.foss@linaro.org, linux-amlogic@lists.infradead.org, linux-arm-kernel@lists.infradead.org References: <20210416092737.1971876-1-narmstrong@baylibre.com> <96b9e144-0791-4c19-3e3c-b0e9efb86138@baylibre.com> From: Neil Armstrong Organization: Baylibre Message-ID: <0821533b-9e6a-237e-3845-741e82de4ed9@baylibre.com> Date: Tue, 20 Apr 2021 17:19:52 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 20/04/2021 17:13, Hans Verkuil wrote: > On 16/04/2021 13:38, Neil Armstrong wrote: >> On 16/04/2021 11:58, Laurent Pinchart wrote: >>> Hi Neil, >>> >>> On Fri, Apr 16, 2021 at 11:27:35AM +0200, Neil Armstrong wrote: >>>> This adds DW-HDMI driver a glue option to disable loading of the CEC sub-driver. >>>> >>>> On some SoCs, the CEC functionality is enabled in the IP config bits, but the >>>> CEC bus is non-functional like on Amlogic SoCs, where the CEC config bit is set >>>> but the DW-HDMI CEC signal is not connected to a physical pin, leading to some >>>> confusion when the DW-HDMI CEC controller can't communicate on the bus. >>> >>> If we can't trust the CEC config bit, would it be better to not use it >>> at all, and instead let each platform glue logic tell whether to enable >>> CEC or not ? >> >> Actually, the CEC config bit is right, the HW exists and should be functional, but >> this bit doesn't tell if the CEC signal is connected to something. >> >> This lies in the IP integration, like other bits under the "amlogic,meson-*-dw-hdmi" >> umbrella. >> >> The first attempt was by Hans using DT, but adding a property in DT for a vendor >> specific compatible doesn't make sense. Another idea would be to describe the >> CEC signal endpoint like we do for video signal, but I think this is out of scope and >> this solution is much simpler and straightforward, and it's more an exception than >> a general use case to solve. > > While a DT property might not make sense in this particular case, I still > believe that it is a perfectly valid approach in general: whether or not > the CEC pin is connected is at the hardware level decision, it is not > something that software can detect. If the designer of the board didn't > connect it, then the only place you can define that is in the device tree. Agreed, we need to define a smart way to declare CEC bus relationship in DT, the side effect would be to handle this particular case. > > Anyway, for meson I am fine with this solution. At least it prevents creating > a non-functioning cec device. So for this series: > > Acked-by: Hans Verkuil Thanks, Applying this serie to drm-misc-next Neil > > Regards, > > Hans > >> >> Neil >> >>> >>>> Jernej Skrabec (1): >>>> drm/bridge/synopsys: dw-hdmi: Add an option to suppress loading CEC >>>> driver >>>> >>>> Neil Armstrong (1): >>>> drm/meson: dw-hdmi: disable DW-HDMI CEC sub-driver >>>> >>>> drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 2 +- >>>> drivers/gpu/drm/meson/meson_dw_hdmi.c | 1 + >>>> include/drm/bridge/dw_hdmi.h | 2 ++ >>>> 3 files changed, 4 insertions(+), 1 deletion(-) >>>> >>> >> >> _______________________________________________ >> dri-devel mailing list >> dri-devel@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/dri-devel >> >