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 X-Spam-Level: X-Spam-Status: No, score=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D347C12002 for ; Mon, 19 Jul 2021 12:04:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E9F0D60FDA for ; Mon, 19 Jul 2021 12:04:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236654AbhGSLXr (ORCPT ); Mon, 19 Jul 2021 07:23:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:54666 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236332AbhGSLXq (ORCPT ); Mon, 19 Jul 2021 07:23:46 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1C0636113C; Mon, 19 Jul 2021 12:04:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626696266; bh=r7MtcETmmwaxyZEhNTXDUCs5QkEaZXwKjSSDkYAiMLw=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=W5Xy8un6pjJrHiVOsd8DmDafSsjlJWAInL+v0gJIEmIxrXRc7R0xXJVF4v+4fNiQp TehCmkISibsQJbqqNWYP2AziPXEl7cyVVZGTH6+Xh9ONmwC8SQGlDqARlw5tGrPQkk kli8lASv66H2za4ziO3KzyNe/FGNAGi3kOcU5fmzhg/mu1b2ZNbKYr5TVeyiXwHJfh 0B6cZZsjmoRNnyzgPSJxs8n52GNO6Mv1R/7GqPfMlTlT6XSvoZoWd/wNWmnnf98eWy PJbVvrTOhtm2REBU0HlAMarUMyATtwZbpJGeT4LSj2K22F3KKyB3UaHlJ5M66mfRrg ufapHNtQUYXbw== Received: by mail-wm1-f43.google.com with SMTP id l18-20020a1ced120000b029014c1adff1edso12675026wmh.4; Mon, 19 Jul 2021 05:04:25 -0700 (PDT) X-Gm-Message-State: AOAM532jEN6E4efbNQgXnuOeoUu/jTvFedzcqu29+MAxf8k5+7aTJ3CN 6H1m520FBy9adaTRyLYUl1Pw1PV971TCwcgniIs= X-Google-Smtp-Source: ABdhPJyTLcL//uJgze/98z6NMZhekHRl1kr2RmyhG5NvFls6ynDEOwrdcVOH94odcgnCHsoc3BpRobMSS124oOCE/rw= X-Received: by 2002:a7b:c2fa:: with SMTP id e26mr31950216wmk.84.1626696264701; Mon, 19 Jul 2021 05:04:24 -0700 (PDT) MIME-Version: 1.0 References: <20210713151917.zouwfckidnjxvohn@vireshk-i7> <20210719103336.oyz6dppd5jf65w4m@vireshk-i7> In-Reply-To: <20210719103336.oyz6dppd5jf65w4m@vireshk-i7> From: Arnd Bergmann Date: Mon, 19 Jul 2021 14:04:08 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 1/5] dt-bindings: virtio: mmio: Add support for device subnode To: Viresh Kumar Cc: Rob Herring , Jason Wang , "Michael S. Tsirkin" , Jean-Philippe Brucker , Vincent Guittot , Bill Mills , =?UTF-8?B?QWxleCBCZW5uw6ll?= , "Enrico Weigelt, metux IT consult" , Jie Deng , DTML , "linux-kernel@vger.kernel.org" , "open list:DRM DRIVER FOR QEMU'S CIRRUS DEVICE" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 19, 2021 at 12:34 PM Viresh Kumar wrote: > On 14-07-21, 23:07, Arnd Bergmann wrote: > > On Wed, Jul 14, 2021 at 5:43 PM Rob Herring wrote: > > > I guess it comes down to is 'virtio,mmio' providing a bus or is it > > > just a device? I guess a bus (so 2 nodes) does make sense here. > > > 'virtio,mmio' defines how you access/discover the virtio queues (the > > > bus) and the functional device (i2c, gpio, iommu, etc.) is accessed > > > via the virtio queues. > > > > It's not really a bus since there is only ever one device behind it. > > A better analogy would be your 'serdev' framework: You could > > have a 8250 or a pl011 uart, and behind that have a mouse, GPS > > receiver or bluetooth dongle. > > > > In Documentation/devicetree/bindings/serial/serial.yaml, you also > > have two nodes for a single device, so we could follow that > > example. > > So two device nodes is final then ? Pretty much like how this patchset did it > already ? I need to get rid of reg thing and use "virtio,DID" though. Let's give Rob another day to reply here. I think two nodes is easier to get working than one node, even when we continue supporting the current iommu binding that relies on a single node, but we could make it work either way if necessary. Arnd