From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-189.mta0.migadu.com (out-189.mta0.migadu.com [91.218.175.189]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F26FC13BC18; Fri, 1 Nov 2024 03:49:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.189 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730432962; cv=none; b=bZ1JQtBh/FmxTtfE9Q1EkXm9PhEsqm3u6Tg9DAyyAq5NNT7hL1wgaWNgiXV3ihFOm3cxmedhevNu+2BL5lR9HAjFE3QX0ZPaJqGxJlEgSeHP4GtmBf3iPAwCO4+j6S/KN2HsARYN1+/y1GwKtko1a3Pb7OwSRueIE8zcrD+wbjo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730432962; c=relaxed/simple; bh=ITlk7toW7r+/8ai/vHURhDUElQIuKW6j+3xWJJXBal4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=LuJ81GOPJu18tcMpI2L7yNgSFfvPmzXsxwdDArdGGsaEuAk7qqtj74P3ayCN0QLIxzjuwovAKI95jqeIUKB9mi5V3gYv5v1OuTUjdR/1t0EcI0Vg1JujL2qCUszoakOHHRnqBgX3Qg0DI6t98yUs0+ALRVvMiAui1NAm8HVQwrw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=Y++Ha3+I; arc=none smtp.client-ip=91.218.175.189 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="Y++Ha3+I" Message-ID: <30fefafc-d19a-40cb-bcb1-3c586ba8e67e@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1730432957; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+aisCwM6KP9qhKb2kb76HEqZmfimYG5W48SHq8fMVq8=; b=Y++Ha3+Inw7JOluD44nkAOSKEmpOHi1RI6ERF950vDTo2tE4evJIgqeCCjhUGWnS3wOJLE KJLrcTTGP+Ayn1k31dYjysjoFgR/A1qCWb/jV/ZUx5Gngphix6NPathal7tWHsLdSmdcF/ QK6CmqO46uFanBZJj0jAq2gK7lGlG3c= Date: Fri, 1 Nov 2024 11:49:07 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v2] drm/bridge: Fix assignment of the of_node of the parent to aux bridge To: Johan Hovold Cc: neil.armstrong@linaro.org, Andrzej Hajda , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Abel Vesa , Dmitry Baryshkov , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20241018-drm-aux-bridge-mark-of-node-reused-v2-1-aeed1b445c7d@linaro.org> <172951608323.1285208.3162107667310691864.b4-ty@linaro.org> <230b5910-6790-44cb-90ed-222bee89054d@linux.dev> <751a4ab5-acbf-4e57-8cf4-51ab10206cc9@linux.dev> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Sui Jingfeng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 2024/11/1 00:23, Johan Hovold wrote: > On Thu, Oct 31, 2024 at 11:06:38PM +0800, Sui Jingfeng wrote: > >> But I think Johan do need more times to understand what exactly >> the real problem is. We do need times to investigate new method. > No, I know perfectly well what the (immediate) problem is here (I was > the one adding support for the of_node_reused flag some years back). > > I just wanted to make sure that the commit message was correct and > complete before merging (and also to figure out whether this particular > patch needed to be backported). Well under such a design, having the child device sharing the 'OF' device node with it parent device means that one parent device can *only* create one AUX bridge child device. Since If you create two or more child AUX bridge, *all* of them will call devm_drm_of_get_bridge(&auxdev->dev, auxdev->dev.of_node, 0, 0), then we will *contend* the same next bridge resource. Because of the 'auxdev->dev.of_node' is same for all its instance. While other display bridges seems don't has such limitations. > Johan -- Best regards, Sui