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=-9.0 required=3.0 tests=BAYES_00,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 B92FDC433C1 for ; Wed, 24 Mar 2021 21:19:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 742C961A09 for ; Wed, 24 Mar 2021 21:19:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233583AbhCXVSy (ORCPT ); Wed, 24 Mar 2021 17:18:54 -0400 Received: from mail-pj1-f44.google.com ([209.85.216.44]:45628 "EHLO mail-pj1-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230336AbhCXVSv (ORCPT ); Wed, 24 Mar 2021 17:18:51 -0400 Received: by mail-pj1-f44.google.com with SMTP id kr3-20020a17090b4903b02900c096fc01deso24150pjb.4; Wed, 24 Mar 2021 14:18:51 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=7uEcEQcGd9DID82dc3J2JnCkttWzlorSElofSVje6So=; b=M7xG8c4z068jlvHtJ9cdB6ixsAj6MIz4Xv4UcTORRnEhumkCpoZ+xEcqGKW9od++YN vQbSJmU0eH/OsxmvLM8hLLG5Eh0jpbpeqGZVguEcYJjwZ4JlSKkEkcK+GmXc4FuoLEe3 /BdOOUo5A6q1YlfXOFMi35cZ7Rw8CXSuFusnA8zQ72n/+tcqIvIU/GlYi0kR53J30OUI pHo7UzGvrEcwUoUPKmlGzmDN+cr4AwbfrFHKEtbkN/C6PWaZKIkaOsNrqjgNWlDeSgjs brr2VSqwpk1NFKyM4rRrHC4weUC+PBi88LCFI1RRbIMEm4H2JyJMGLGtdeKaakbZ/xaI f3Wg== X-Gm-Message-State: AOAM532CEpkTPgiPrJ76vyU70bT32affi/vt2nttdJZR4Lea8j5W4+L5 1x+G+mKf73vJwt9BbbE4EpTe7qVHrB4= X-Google-Smtp-Source: ABdhPJw1rgkGoxtrSIiVZpmGlG7v5sNipw9QTG++lHhgwXXaUi816Rp6j+SQ2+11AKqYuAl3qv26Fg== X-Received: by 2002:a17:90a:bb02:: with SMTP id u2mr5475413pjr.175.1616620730785; Wed, 24 Mar 2021 14:18:50 -0700 (PDT) Received: from localhost ([2601:647:5b00:1161:a4cc:eef9:fbc0:2781]) by smtp.gmail.com with ESMTPSA id t16sm3445348pfc.204.2021.03.24.14.17.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Mar 2021 14:17:59 -0700 (PDT) Date: Wed, 24 Mar 2021 14:17:08 -0700 From: Moritz Fischer To: Xu Yilun Cc: mdf@kernel.org, gregkh@linuxfoundation.org, linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org, trix@redhat.com, lgoncalv@redhat.com, hao.wu@intel.com Subject: Re: [PATCH v12 0/2] UIO support for dfl devices Message-ID: References: <1615168776-8553-1-git-send-email-yilun.xu@intel.com> <20210324082217.GA405791@yilunxu-OptiPlex-7050> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210324082217.GA405791@yilunxu-OptiPlex-7050> Precedence: bulk List-ID: X-Mailing-List: linux-fpga@vger.kernel.org Hi Xu, On Wed, Mar 24, 2021 at 04:22:17PM +0800, Xu Yilun wrote: > Hi Moritz: > > Sorry I need to get back to you again, seems no more comments from Greg. > > The patchset is stuck here for more than 1 month. Do you have some > more suggestion that could make it move forward? Do you have some more > comments? Or give an acked-by? Or could you apply it to your fpga branch > and go with next pull request? In its current form it's a UIO driver and needs at least Greg's Acked-by before I could apply it. Greg, can you take another look? > > Thanks, > Yilun > > On Mon, Mar 08, 2021 at 09:59:34AM +0800, Xu Yilun wrote: > > This patchset supports some dfl device drivers written in userspace. > > > > There are some Q&A about why UIO driver is needed in v11: > > > > >From Greg: > > Why are you saying that an ethernet driver should be using the UIO > > interface? > > > > And why can't you use the existing UIO drivers that bind to memory > > regions specified by firmware? Without an interrupt being used, why is > > UIO needed at all? > > > > >From Moritz: > > Essentially I see two options: > > - Have a DFL bus driver instantiate a platform driver (uio_pdrv_genirq) > > which I *think* you described above? > > - What this patch implements -- a UIO driver on the DFL bus > > > > These FPGA devices can on the fly change their contents and -- even if > > just for test -- being able to expose a bunch of registers via UIO can > > be extremely useful. > > > > Whether a device should expose registers or not should be up to the > > implemeneter of the FPGA design I think (policy). This patch (or the > > previous version) provides a mechanism to do so via DFL. > > > > This is similar in nature to uio_pdrv_genirq on a DT based platform, to > > expose the registers you instantiate the DT node. > > > > Re-implementing a new driver for each of these instances doesn't seem > > desirable and tying DFL as enumeration mechanism to UIO seems like a > > good compromise for enabling this kind of functionality. > > > > Note this is *not* an attempt to bypass the network stack or other > > existing subsystems. > > > > See the original message in: > > https://lore.kernel.org/linux-fpga/YDvQ8aO8v3NhLKzx@epycbox.lan/T/#m66ba2c96848e3dea38d1a4f16dfea3cb291f7975 > > > > > > >From Yilun: > > The ETH GROUP IP is not designed as the full functional ethernet > > controller. It is specially developed for the Intel N3000 NIC. Since it > > is an FPGA based card, it is designed for the users to runtime reload > > part of the MAC layer logic developed by themselves, while the ETH GROUP > > is another part of the MAC which is not expected to be reloaded by > > customers, but it provides some configurations for software to work with > > the user logic. > > > > So I category the feature as the devices that "designed for specific > > purposes and does not fit into one of the standard kernel subsystems". > > Some related description could be found in Patch #2, to illustrate why > > using UIO for some DFL devices. > > > > There are now UIO drivers for PCI or platform devices, but in this case > > we are going to export a DFL(Device Feature List) bus device to > > userspace, a DFL driver for UIO is needed to bind to it. > > > > See the original message in: > > https://lore.kernel.org/linux-fpga/YDvQ8aO8v3NhLKzx@epycbox.lan/T/#m91b303fd61485644353fad1e1e9c11d528844684 > > > > > > Xu Yilun (2): > > uio: uio_dfl: add userspace i/o driver for DFL bus > > Documentation: fpga: dfl: Add description for DFL UIO support > > > > Documentation/fpga/dfl.rst | 26 ++++++++++++++++++ > > MAINTAINERS | 1 + > > drivers/uio/Kconfig | 17 ++++++++++++ > > drivers/uio/Makefile | 1 + > > drivers/uio/uio_dfl.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++ > > 5 files changed, 111 insertions(+) > > create mode 100644 drivers/uio/uio_dfl.c > > > > -- > > 2.7.4 Thanks, Moritz