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=-13.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 EFD61C4361A for ; Fri, 4 Dec 2020 16:42:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B337522AED for ; Fri, 4 Dec 2020 16:42:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730747AbgLDQl6 (ORCPT ); Fri, 4 Dec 2020 11:41:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57948 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726526AbgLDQl4 (ORCPT ); Fri, 4 Dec 2020 11:41:56 -0500 Received: from mail-ed1-x543.google.com (mail-ed1-x543.google.com [IPv6:2a00:1450:4864:20::543]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CF637C061A51 for ; Fri, 4 Dec 2020 08:41:15 -0800 (PST) Received: by mail-ed1-x543.google.com with SMTP id ck29so6470374edb.8 for ; Fri, 04 Dec 2020 08:41:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=0DSnVIqhCjfQRKv2sQg9Q6JdfEOfBg7tXO7oAxFOt6Q=; b=0yetlJbYMnmdPmLRUZn7RS3bh0tzdzDGM+9PDleeD2iqRFXkNd6mRf3f03rSWgmQd5 qOdHp/kup+NAYxh/CJU9LLba4DAwBUgERhl0M4qXHOiXVt1fco+LP77vh1cyZ6qq4c/8 foxoZxB5HbKBzb5iEeajTCsLfYovy0DkhPTg2Vx19iICqqPRG/USmccONRumHiexn6TT emAV80gchfWJPgkMYOcf5EbJkWMDGA1M8o5UgQZIurDf8zmRVSOw/6i4VpmZ4L3VjJY1 Lb0/f/PdqHE31Hd1g7ro/aT6mcyIWyq6RwBrvqipCdwmt+1rH+sEiJAwqvHPxCuIWtFs z3iQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=0DSnVIqhCjfQRKv2sQg9Q6JdfEOfBg7tXO7oAxFOt6Q=; b=IcqUAQ+mg3XYAHSQQ98Z6cNqBVDF7KcRJLRFE+HBTMN9qIpc+czB5ih62rz1xsVpW7 V+Ho8k/BGALm6FJaSuz0geQJRDaZr9U6SKV4Meko3cCPadpQSdyIAG2r6AiezFw0XkTt Yhyq3DTX4YPEfXpjlSOGnJAnLHdRfPCR06QiUsKhk+aYjkuqUYW0or641lvxsZAAeHy5 nAl73VNi2vd7+VIxXFws6/JjSjtVGsLZPRhSgVg6tnNqitREhNKr8fAyAGgseflGEhTE 3ZFqXujy9x3TD3MvKmR/cp4QqZlZTl4fc7pVyQfPI/ghmO+QVdEUSjn4AX16HsTMTXFt K+bA== X-Gm-Message-State: AOAM532MA79iTrFrdKNtKKh/Evnqq09/ucv6DGq0SLgan0MyykcGN3Qe 7TrqmYzh6uJTadDbE9VPxtn+tfHaR2OXXNRVUXlcqA== X-Google-Smtp-Source: ABdhPJwaZ4haRtuDzBD84WdDW7otHcrepP4bW/OgCJDuVGkx8fNTTRTGsYJMeW0OBOxCy0odLqO+2rTLHMU2+xmnxS8= X-Received: by 2002:aa7:cdc3:: with SMTP id h3mr2165444edw.52.1607100074435; Fri, 04 Dec 2020 08:41:14 -0800 (PST) MIME-Version: 1.0 References: <160695681289.505290.8978295443574440604.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: From: Dan Williams Date: Fri, 4 Dec 2020 08:41:09 -0800 Message-ID: Subject: Re: [resend/standalone PATCH v4] Add auxiliary bus support To: Greg KH Cc: Mark Brown , Liam Girdwood , David Miller , Jakub Kicinski , Jason Gunthorpe , Kiran Patil , Ranjani Sridharan , Fred Oh , Leon Romanovsky , Dave Ertman , Pierre-Louis Bossart , Shiraz Saleem , Parav Pandit , Martin Habets , linux-rdma , Netdev , alsa-devel@alsa-project.org, Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 4, 2020 at 3:41 AM Greg KH wrote: > > On Wed, Dec 02, 2020 at 04:54:24PM -0800, Dan Williams wrote: > > From: Dave Ertman > > > > Add support for the Auxiliary Bus, auxiliary_device and auxiliary_driver. > > It enables drivers to create an auxiliary_device and bind an > > auxiliary_driver to it. > > > > The bus supports probe/remove shutdown and suspend/resume callbacks. > > Each auxiliary_device has a unique string based id; driver binds to > > an auxiliary_device based on this id through the bus. > > > > Co-developed-by: Kiran Patil > > Co-developed-by: Ranjani Sridharan > > Co-developed-by: Fred Oh > > Co-developed-by: Leon Romanovsky > > Signed-off-by: Kiran Patil > > Signed-off-by: Ranjani Sridharan > > Signed-off-by: Fred Oh > > Signed-off-by: Leon Romanovsky > > Signed-off-by: Dave Ertman > > Reviewed-by: Pierre-Louis Bossart > > Reviewed-by: Shiraz Saleem > > Reviewed-by: Parav Pandit > > Reviewed-by: Dan Williams > > Reviewed-by: Martin Habets > > Link: https://lore.kernel.org/r/20201113161859.1775473-2-david.m.ertman@intel.com > > Signed-off-by: Dan Williams > > --- > > This patch is "To:" the maintainers that have a pending backlog of > > driver updates dependent on this facility, and "Cc:" Greg. Greg, I > > understand you have asked for more time to fully review this and apply > > it to driver-core.git, likely for v5.12, but please consider Acking it > > for v5.11 instead. It looks good to me and several other stakeholders. > > Namely, stakeholders that have pressure building up behind this facility > > in particular Mellanox RDMA, but also SOF, Intel Ethernet, and later on > > Compute Express Link. > > > > I will take the blame for the 2 months of silence that made this awkward > > to take through driver-core.git, but at the same time I do not want to > > see that communication mistake inconvenience other parties that > > reasonably thought this was shaping up to land in v5.11. > > > > I am willing to host this version at: > > > > git://git.kernel.org/pub/scm/linux/kernel/git/djbw/linux tags/auxiliary-bus-for-5.11 > > > > ...for all the independent drivers to have a common commit baseline. It > > is not there yet pending Greg's Ack. > > > > For example implementations incorporating this patch, see Dave Ertman's > > SOF series: > > > > https://lore.kernel.org/r/20201113161859.1775473-2-david.m.ertman@intel.com > > > > ...and Leon's mlx5 series: > > > > http://lore.kernel.org/r/20201026111849.1035786-1-leon@kernel.org > > > > PS: Greg I know I promised some review on newcomer patches to help with > > your queue, unfortunately Intel-internal review is keeping my plate > > full. Again, I do not want other stakeholder to be waiting on me to > > resolve that backlog. > > Ok, I spent some hours today playing around with this. I wrote up a > small test-patch for this (how did anyone test this thing???) and while > it feels awkward in places, and it feels like there is still way too > much "boilerplate" code that a user has to write and manage, I don't > have the time myself to fix it up right now. > > So I'll go apply this to my tree, and provide a tag for everyone else to > be able to pull from for their different development trees so they can > work on. > > I do have 3 follow-on patches that I will send to the list in response > to this message that I will be applying on top of this patch. They do > some minor code formatting changes, as well as change the return type of > the remove function to make it more future-proof. That last change will > require users of this code to change their implementations, but it will > be obvious what to do as you will get a build warning. > > Note, I'm still not comfortable with a few things here. The > documentation feels odd, and didn't really help me out in writing any > test code, which doesn't seem right. Also the use of strings and '.' as > part of the api feels awkward, and messy, and of course, totally > undocumented. > > But, as the use of '.' is undocumented, that means we can change it in > the future! Because no driver or device name should ever be a user api > reliant thing, if we come up with a better way to do all of this in the > future, that shouldn't be a problem to change existing users over to > this. So this is a warning to everyone, you CAN NOT depend on the sysfs > name of a device or bus name for any tool. If so, your userspace tool > is broken. > > Thanks for everyone in sticking with this, I know it's been a long slog, > hopefully this will help some driver authors move forward with their > crazy complex devices :) To me, the documentation was written, and reviewed, more from the perspective of "why not open code a custom bus instead". So I can see after the fact how that is a bit too much theory and justification and not enough practical application. Before the fact though this was a bold mechanism to propose and it was not clear that everyone was grokking the "why" and the tradeoffs. I also think it was a bit early to identify consistent design patterns across the implementations and codify those. I expect this to evolve convenience macros just like other parts of the driver-core gained over time. Now that it is in though, another pass through the documentation to pull in more examples seems warranted.