From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.manjaro.org (mail.manjaro.org [116.203.91.91]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 12F7E47A66; Tue, 6 Aug 2024 15:39:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=116.203.91.91 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722958784; cv=none; b=eD0DqeTrIqAaQciijBY0N3mmwYuj8EyRHaNU3CsQobjvA9CUG9WWX0/S5iaV2biWfcGdGgMOjcIMlb6R8WRVDmAPCpvgWSlHWa4QbC8F1PJ02f/cYh733tXoI+kS3Jj5LilLBCfZYhGO3TXN4q3g4wDjh3jyymX2sH378rYA7Uo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722958784; c=relaxed/simple; bh=b7ozdsbwfMXW21Tyt4Tt33Hq8k141H7HbyANf37oXi0=; h=MIME-Version:Date:From:To:Cc:Subject:In-Reply-To:References: Message-ID:Content-Type; b=Exu/7ZxuqQ50IVqnX8ulsJO0jY9g1patois89mH9Nw5tp7l5cEV+KJz/q1d4zd+NpV+DIn09g5ICvScnUBgFW0wo48mO3ts4E1OyH0MUZ6BJrKWQAZvR7CXoSI7lhwJIVctWkhRIq+oKsivU3C9afaS8/W59pMsnyZHmZqSRHDU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=manjaro.org; spf=pass smtp.mailfrom=manjaro.org; dkim=pass (2048-bit key) header.d=manjaro.org header.i=@manjaro.org header.b=VfEMfp9v; arc=none smtp.client-ip=116.203.91.91 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=manjaro.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=manjaro.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=manjaro.org header.i=@manjaro.org header.b="VfEMfp9v" Precedence: bulk X-Mailing-List: linux-mmc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=manjaro.org; s=2021; t=1722958773; 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=2Chn8ymlqazavJ1DZmXPdLBrye9DBk3cugxlezlxhvc=; b=VfEMfp9veTf9vofJGHvARhjKJLQWxXoE6CZ4ZfPJBcyubeBt6RFYznvEmk0qhNLGaLcWIZ V4ZVilXZpCU9C/H3Fj/ysZ/XgET0TF1ZDcxMeq8V3CyxyQdsNk7NIj2fbogg2t01z7WsLv wvZqgRJCniv7XWLsHstRuSCgMls15R5RXpdkYXYEbuirc0/HNhXfXfbC+UTQp1+RTHuNyc HQCGgdhhrNGrjo/ZN4a8er9JdyzG+eHz0KiwhMuHq/wV0VtW6AozR7DoRbDrDnLY5G34gi SGgRl+hV/9eqi04hVkBzZk6CNzURj7hKvvnqvMopGb0w7ymNHesO9/LnmyrCtw== Date: Tue, 06 Aug 2024 17:39:32 +0200 From: Dragan Simic To: Christian Marangi Cc: Christoph Hellwig , Ulf Hansson , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , Joern Engel , Keith Busch , Jens Axboe , Sagi Grimberg , Wolfram Sang , Florian Fainelli , Thomas Bogendoerfer , linux-mmc@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, linux-nvme@lists.infradead.org Subject: Re: [PATCH v3 2/6] nvme: assign of_node to nvme device In-Reply-To: <66b21f20.5d0a0220.200175.4b9b@mx.google.com> References: <20240806114118.17198-1-ansuelsmth@gmail.com> <20240806114118.17198-3-ansuelsmth@gmail.com> <20240806124312.GB10156@lst.de> <66b21f20.5d0a0220.200175.4b9b@mx.google.com> Message-ID: X-Sender: dsimic@manjaro.org Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Authentication-Results: ORIGINATING; auth=pass smtp.auth=dsimic@manjaro.org smtp.mailfrom=dsimic@manjaro.org Hello all, On 2024-08-06 15:03, Christian Marangi wrote: > On Tue, Aug 06, 2024 at 02:43:12PM +0200, Christoph Hellwig wrote: >> On Tue, Aug 06, 2024 at 01:41:12PM +0200, Christian Marangi wrote: >> > Introduce support for a dedicated node for a nvme card. This will be a >> > subnode of the nvme controller node that will have the "nvme-card" >> > compatible. >> > >> > This follow a similar implementation done for mmc where the specific mmc >> > card have a dedicated of_node. >> > >> > This can be used for scenario where block2mtd module is used to declare >> > partition in DT and block2mtd is called on the root block of the nvme >> > card, permitting the usage of fixed-partition parser or alternative >> > ones. >> >> Err, hell no. Why would you wire up a purely PCIe device to OF? >> PCIe is self-discovering. >> > > Well on embedded pure PCIe card most of the time are not a thing... > Unless it's an enterprise product, everything is integrated in the pcb > and not detachable for cost saving measure or also if the thing use > PCIe > protocol but it tighlty coupled with the SoC. > > This implementation is already very common for all kind of pcie devices > like wireless card, gpio expander that are integrated in the PCB and > require property in DT like calibration data, quirks or GPIO pin > definitions, i2c... > > In modern SoC we are seeing an influx of using cheap flash storage > option instead of NAND or NOR as modern hw require more space and price > increase is not that high... Almost any high tier device is switching > to > using emmc and even attached NVME and simulating MTD with them for easy > usage. > > Please consider this well used scenario in emebedded where PCIe is just > a comunication way and the concept of detachable doesn't exist at all > and things can be described in DT as static. Also these storage are > used > for rootfs mount so userspace is not so viable. As a note, perhaps this is another good example of a "fixed layout" PCIe device found on an SBC: https://lore.kernel.org/linux-rockchip/20240805073425.3492078-1-jacobe.zang@wesion.com/T/#u