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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9545DCD13CF for ; Tue, 3 Sep 2024 09:11:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: Content-Transfer-Encoding:Content-Type:MIME-Version:References:In-Reply-To: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=7LttFW8rTrdCnShZkP1nFG0SbHb65v/96Px6RosbpqQ=; b=I77HVwymqhjdjc gGuXktIxR5ZvxacVTskohWi2CTdfuick4JllxQ+Yt1D9vlAv9lYMXbFpePMgG6puPCk/ZuK3qfuWt w/tDV1FGpxU3Pf338IdMl/XnJjALKjYzx7/nY50y1O9PPTdOHwh5bHbvMWQlBnWwe1uBri9VU9ndF wjvMgXlRhU/vjsY3kgZWxWWExuDN/eRWDKhoxXCUXY25egutbF6ZryXeqcPZVIEAtl2odchBb8S5Q MUHFLhMQ0JoJWJfxzJ/UTrzenjwdd7wtpuHIHrrZxKczQhbkglvrwni9Bxc0IZMfh8NTwHys2m0kA BBqvaj3oVCuNcIsd7egA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1slPYu-0000000H4pZ-2oSq; Tue, 03 Sep 2024 09:10:56 +0000 Received: from relay2-d.mail.gandi.net ([217.70.183.194]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1slPXz-0000000H4ah-1GnG; Tue, 03 Sep 2024 09:10:01 +0000 Received: by mail.gandi.net (Postfix) with ESMTPSA id C13424000B; Tue, 3 Sep 2024 09:09:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1725354597; 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=7LttFW8rTrdCnShZkP1nFG0SbHb65v/96Px6RosbpqQ=; b=YLjxJgQeUItsVJ9gFA+6szbHMMcy/jFztLjUTtOdnTE1kJJ1YNpr5SWSmSzrQ0Fcor3gGz 8UO1UWSm2NNGYm+PEtn65EfyIIl8iL8anFMsQ9vGc8MRsVuZ4Cyak/fSmlA/R2uLfCjrlM XV9M2ZBOonlf+tO2sq2fJH7BtgFCKOgfePeGYqVoKJWChjb6MCbFLuJYCgbfq5/VL32JIG 9co31FIV9mpNOR7bRqHir+gL6DLowcQyXHkn1phPVoBTQVnidadKcHuyPSdJ4LM/gO013j 1E2uC57WvRuf0xJig2u1sfnT4uLMBRKvZZ9Ujr+I2eqYvrf50qlmXpWBKmodyw== Date: Tue, 3 Sep 2024 11:09:53 +0200 From: Herve Codina To: Rob Herring Subject: Re: [PATCH 04/11] of: address: Preserve the flags portion on 1:1 dma-ranges mapping Message-ID: <20240903110953.2b1f55b6@bootlin.com> In-Reply-To: References: <5ca13a5b01c6c737f07416be53eb05b32811da21.1724159867.git.andrea.porta@suse.com> <20240821001618.GA2309328-robh@kernel.org> Organization: Bootlin X-Mailer: Claws Mail 4.3.0 (GTK 3.24.43; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-GND-Sasl: herve.codina@bootlin.com X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240903_020959_940113_180B239D X-CRM114-Status: GOOD ( 32.86 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Andrew Lunn , Catalin Marinas , Michael Turquette , Claudiu Beznea , Eric Dumazet , Dragan Cvetic , Thomas Petazzoni , Will Deacon , linux-clk@vger.kernel.org, linux-arch@vger.kernel.org, Florian Fainelli , Lee Jones , Saravana Kannan , Broadcom internal kernel review list , linux-pci@vger.kernel.org, Jakub Kicinski , Paolo Abeni , Luca Ceresoli , Linus Walleij , devicetree@vger.kernel.org, Conor Dooley , Arnd Bergmann , linux-gpio@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, Bjorn Helgaas , Andrea della Porta , linux-arm-kernel@lists.infradead.org, Derek Kiernan , Stephen Boyd , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Stefan Wahren , netdev@vger.kernel.org, Krzysztof Kozlowski , "David S. Miller" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi, On Fri, 30 Aug 2024 14:37:54 -0500 Rob Herring wrote: ... > > this view is much like Bootlin's approach, also my pci-ep-bus node now would look > > like this: > > ... > > pci-ep-bus@0 { > > ranges = <0xc0 0x40000000 > > 0x01 0x00 0x00000000 > > 0x00 0x00400000>; > > ... > > }; > > > > and also the correct unit address here is 0 again, since the parent address in > > ranges is 0x01 0x00 0x00000000 (0x01 is the flags and in this case represent > > BAR1, I assume that for the unit address I should use only the address part that > > is 0, right?). > > No, it should be 1 for BAR1. It's 1 node per BAR. It should be 1 node per BAR but in some cases it is not. Indeed, in the LAN966x case, the pci-ep-bus need to have access to several BARs and we have: ... pci-ep-bus@0 { compatible = "simple-bus"; #address-cells = <1>; #size-cells = <1>; /* * map @0xe2000000 (32MB) to BAR0 (CPU) * map @0xe0000000 (16MB) to BAR1 (AMBA) */ ranges = <0xe2000000 0x00 0x00 0x00 0x2000000 0xe0000000 0x01 0x00 0x00 0x1000000>; ... Some devices under this bus need to use both BARs and use two regs values in their reg properties to access BAR0 and BAR1. > > > > > The assumption so far with all of this is that you have some specific > > > > > PCI device (and therefore a driver). The simple-buses under it are > > > > > defined per BAR. Not really certain if that makes sense in all cases, > > > > > but since the address assignment is dynamic, it may have to. I'm also > > > > > not completely convinced we should reuse 'simple-bus' here or define > > > > > something specific like 'pci-bar-bus' or something. > > > > > > > > Good point. Labeling a new bus for this kind of 'appliance' could be > > > > beneficial to unify the dt overlay approach, and I guess it could be > > > > adopted by the aforementioned Bootlin's Microchip patchset too. > > > > However, since the difference with simple-bus would be basically non > > > > existent, I believe that this could be done in a future patch due to > > > > the fact that the dtbo is contained into the driver itself, so we do > > > > not suffer from the proliferation that happens when dtb are managed > > > > outside. > > > > > > It's an ABI, so we really need to decide first. > > > > Okay. How should we proceed? > > I think simple-bus where you have it is fine. It is really 1 level up > that needs to be specified. Basically something that's referenced from > the specific PCI device's schema (e.g. the RP1 schema (which you are > missing)). > > That schema needs to roughly look like this: > > properties: > "#address-cells": > const: 3 > "#size-cells": > const: 2 > ranges: > minItems: 1 > maxItems: 6 > items: > additionalItems: true > items: > - maximum: 5 # The BAR number > - const: 0 > - const: 0 > - # TODO: valid PCI memory flags > > patternProperties: > "^bar-bus@[0-5]$": > type: object > additionalProperties: true > properties: > compatible: > const: simple-bus > ranges: true > IMHO, the node should not have 'bar' in the name. In the LAN966x PCI use case, multiple BARs have to be accessed by devices under this simple-bus. That's why I choose pci-ep-bus for this node name. Best regards, Hervé