From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (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 D01A615852F; Fri, 1 Nov 2024 09:21:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730452867; cv=none; b=sV37pW9zduoWOhflRRLuCfD1SoDW5aA86qq1A+6ntccVPKX5PWgrQz1kP/1jKIk1X/fRSzpAAhSfoXeADWHNEQdKT6lxmHo2a23Dn1IzxooJT0/D/bguhIyOFMJXjtsWwMkb232KyU5aHWcA8xbm0Tl++v1z1Jf+MMUhN85k0rU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730452867; c=relaxed/simple; bh=DvGdTgJ/Dg9JlFjF6NE7OmksllUnclX4NbH7Ot6PLFk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=h5OOF1eL6G4FP5NBwHLtnJlfbrKqmX5kkCeOLQyd2OxH7A73yybcpCd1SrSBhjATqa/AIpCtl32/4yyfRzAtCBLCaxW20/wKmdmqsKjCS5870HbeCIAfOfEPAtRPovP21T70EGlJtnUGMVXzlXBZ8Y6POpm5S5ag9V31w/5uc68= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=UbN1DXSM; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="UbN1DXSM" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 3436D3D4; Fri, 1 Nov 2024 10:20:51 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1730452851; bh=DvGdTgJ/Dg9JlFjF6NE7OmksllUnclX4NbH7Ot6PLFk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UbN1DXSMfqjA+beJQ+tmf2QAG3lWzfRixBwST78dyzID5Q9CUZjnxJr7nuL+mHKC7 9KqXtwICmXxJwrrlbewhGPeNmpBXER55mMZ/MwEtL0UfmLVe1AB9gHssb/XY3xk12l 8eD7F2OUFpTlJ/USFuTALVxl1et5E3n1FS5/5Iuc= Date: Fri, 1 Nov 2024 11:20:49 +0200 From: Laurent Pinchart To: Sui Jingfeng Cc: Johan Hovold , neil.armstrong@linaro.org, Andrzej Hajda , Robert Foss , 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 Subject: Re: [PATCH v2] drm/bridge: Fix assignment of the of_node of the parent to aux bridge Message-ID: <20241101092049.GJ2473@pendragon.ideasonboard.com> 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> <30fefafc-d19a-40cb-bcb1-3c586ba8e67e@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <30fefafc-d19a-40cb-bcb1-3c586ba8e67e@linux.dev> On Fri, Nov 01, 2024 at 11:49:07AM +0800, Sui Jingfeng wrote: > > 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. Brainstorming a bit, I wonder if we could create a swnode for the auxiliary device, instead of reusing the parent's OF node. This would require switching the DRM OF-based APIs to fwnode, but that's easy and mostly a mechanical change. -- Regards, Laurent Pinchart