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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7B43CC38142 for ; Wed, 1 Feb 2023 16:35:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232071AbjBAQfC (ORCPT ); Wed, 1 Feb 2023 11:35:02 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39800 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229615AbjBAQe7 (ORCPT ); Wed, 1 Feb 2023 11:34:59 -0500 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 083DC4690; Wed, 1 Feb 2023 08:34:56 -0800 (PST) Received: by linux.microsoft.com (Postfix, from userid 1127) id B311620B74F8; Wed, 1 Feb 2023 08:34:55 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com B311620B74F8 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1675269295; bh=4c21+WsHMdgERH83tze28bmrMD1U1gRJ4pTq1J2qqYQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=G7vmgFyTp14UCrjNXXNDIWrZLHdUoudSBR2CW2qUMLqCttEtMlcuwNxLv35bRu/sg GN5RS2CUBykO8xIOmm6saDqq+iv1QFNZQPmgMTu6yxSIlqk1JbEw+oc06A/+nNDhom y4ARkooDVwCNDgKQkYpKn1UGaC45j1uyvPibiSuc= Date: Wed, 1 Feb 2023 08:34:55 -0800 From: Saurabh Singh Sengar To: Rob Herring Cc: krzysztof.kozlowski+dt@linaro.org, kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, daniel.lezcano@linaro.org, tglx@linutronix.de, virtualization@lists.linux-foundation.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, mikelley@microsoft.com, ssengar@microsoft.com Subject: Re: [PATCH v2 0/6] Device tree support for Hyper-V VMBus driver Message-ID: <20230201163455.GA21409@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net> References: <1675188609-20913-1-git-send-email-ssengar@linux.microsoft.com> <20230201020449.GC20379@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net> <20230201145146.GA3352796-robh@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230201145146.GA3352796-robh@kernel.org> User-Agent: Mutt/1.5.21 (2010-09-15) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 01, 2023 at 08:51:46AM -0600, Rob Herring wrote: > On Tue, Jan 31, 2023 at 06:04:49PM -0800, Saurabh Singh Sengar wrote: > > On Tue, Jan 31, 2023 at 02:27:51PM -0600, Rob Herring wrote: > > > On Tue, Jan 31, 2023 at 12:10 PM Saurabh Sengar > > > wrote: > > > > > > > > This set of patches expands the VMBus driver to include device tree > > > > support. > > > > > > > > The first two patches enable compilation of Hyper-V APIs in a non-ACPI > > > > build. > > > > > > > > The third patch converts the VMBus driver from acpi to more generic > > > > platform driver. > > > > > > > > Further to add device tree documentation for VMBus, it needs to club with > > > > other virtualization driver's documentation. For this rename the virtio > > > > folder to more generic hypervisor, so that all the hypervisor based > > > > devices can co-exist in a single place in device tree documentation. The > > > > fourth patch does this renaming. > > > > > > > > The fifth patch introduces the device tree documentation for VMBus. > > > > > > > > The sixth patch adds device tree support to the VMBus driver. Currently > > > > this is tested only for x86 and it may not work for other archs. > > > > > > I can read all the patches and see *what* they do. You don't really > > > need to list that here. I'm still wondering *why*. That is what the > > > cover letter and commit messages should answer. Why do you need DT > > > support? How does this even work on x86? FDT is only enabled for > > > CE4100 platform. > > > > HI Rob, > > > > Thanks for your comments. > > We are working on a solution where kernel is booted without ACPI tables to keep > > the overall system's memory footprints slim and possibly faster boot time. > > We have tested this by enabling CONFIG_OF for x86. > > It's CONFIG_OF_EARLY_FLATTREE which you would need and that's not user > selectable. At a minimum, you need some kconfig changes. Where are > those? You are right we have define a new config flag in Kconfig, and selected CONFIG_OF and CONFIG_OF_EARLY_FLATTREE. We are working on upstreaming that patch as well however that will be a separate patch series. > > Also see my comment on v1 about running DT validation on your dtb. I'm > sure running it would point out other issues. Such as the root level > comaptible string(s) need to be documented. You need cpu nodes, > interrupt controller, timers, etc. Those all have to be documented. I will be changing the parent node to soc node as suggested by Krzysztof in other thread. soc { #address-cells = <2>; #size-cells = <2>; vmbus@ff0000000 { #address-cells = <2>; #size-cells = <1>; compatible = "Microsoft,vmbus"; ranges = <0x00 0x00 0x0f 0xf0000000 0x10000000>; }; }; This will be sufficient. Regards, Saurabh > > Rob