From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay6-d.mail.gandi.net (relay6-d.mail.gandi.net [217.70.183.198]) (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 F27A76FC5; Tue, 14 May 2024 17:11:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.183.198 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715706686; cv=none; b=Imt3va4qW1G/mtHfuMJGqlYJHXVv4xDOMaVuY+uEssa0ETwa5yeTBlDFxQAkmYTF6oSADuP0yX5byZbYZpwuDXWG2LdvOjh6ApSnE/Iiyf8RnCPGp0O3lD2qwuD8oZx3Pk4kl8l2EjCft3uGiT1qZlFgMES1GgbF3T28LTDTCHc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715706686; c=relaxed/simple; bh=JOFWO9OkUaqiqQCHDYJAVIjKoCtVTHFpaPviaW6ZoVE=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=EDvqTO6cTARFDjZYs+fbF81VoREKXzv7eh2eeDLbMbbYdpFJp6ybnHyuDatMPkBPvG1y4Bls5h/JZVhuRMEMHNZEJ4TKTszkuhkrX+DaD0dohwSK492AmO9dq6UjV32wDvRuuiy1gkIfyQHaH3XFiKW45beQX6sUopwr1AJpqgE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=h9DaJlGC; arc=none smtp.client-ip=217.70.183.198 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="h9DaJlGC" Received: by mail.gandi.net (Postfix) with ESMTPSA id D2226C000A; Tue, 14 May 2024 17:11:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1715706681; 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=P8Cv6K+hNAOMTSxkND2VnO0L0L1inZAjtqwoyrqFY7A=; b=h9DaJlGC+6C/mDVfK/AsaTg4yxGmOU9QB/6NcMOZzP5nn7EA0QcvVPRb2l73nChCwUWulE 2Q0E3g4kgu71qAAISfkFW983lJZA+9EQmY20pATxXQORSqPihC4fr01C1TyG4zADlhDKUB iekUFtnGyMmRXb5W+MkapjZ4jfmTeO6tST2vwHIm3sVSpUsCzg8CEIp+v/td8+PuDKf4J7 OTie7bIPOgYzbgcEbq2NTUMmaUTI7TQ5ca2byxWD+O5MUzgCO75moKdmluRb5zjLJvfqlc e6WxoGuE3WdXLAEp7KLwCWbDc2yP7A0KbRtjJNH6CdoxnGQgwrg1jZcCHv1USQ== Date: Tue, 14 May 2024 19:11:17 +0200 From: Luca Ceresoli To: Rob Herring Cc: Krzysztof Kozlowski , Conor Dooley , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , Derek Kiernan , Dragan Cvetic , Arnd Bergmann , Greg Kroah-Hartman , Saravana Kannan , Paul Kocialkowski , =?UTF-8?Q?Herv=C3=A9?= Codina , Thomas Petazzoni , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Paul Kocialkowski Subject: Re: [PATCH v2 0/5] Add support for GE SUNH hot-pluggable connector (was: "drm: add support for hot-pluggable bridges") Message-ID: <20240514191117.519b274c@booty> In-Reply-To: <20240510164449.GB336987-robh@kernel.org> References: <20240510-hotplug-drm-bridge-v2-0-ec32f2c66d56@bootlin.com> <20240510164449.GB336987-robh@kernel.org> Organization: Bootlin X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.33; x86_64-pc-linux-gnu) 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=US-ASCII Content-Transfer-Encoding: 7bit X-GND-Sasl: luca.ceresoli@bootlin.com Hello Rob, On Fri, 10 May 2024 11:44:49 -0500 Rob Herring wrote: > On Fri, May 10, 2024 at 09:10:36AM +0200, Luca Ceresoli wrote: [...] > > Overall approach > > ================ > > > > Device tree overlays appear as the most natural solution to support the > > addition and removal of devices from a running system. > > > > Several features are missing from the mainline Linux kernel in order to > > support this use case: > > > > 1. runtime (un)loading of device tree overlays is not supported > > Not true. Device specific applying of overlays has been supported > since we merged DT overlay support. What's not supported is a general > purpose interface to userspace to change any part of the DT at any point > in time. I think I should replace "supported" with "exposed [to user space]". In other words, there is no user of of_overlay_fdt_apply() / of_overlay_remove*() in mainline Linux, except in unittest. Would it be a correct rewording? > > 2. if enabled, overlay (un)loading exposes several bugs > > Hence why there is no general purpose interface. Absolutely. Best regards, Luca -- Luca Ceresoli, Bootlin Embedded Linux and Kernel engineering https://bootlin.com