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=-10.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 C4B65C4346E for ; Sun, 27 Sep 2020 07:54:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5FFFF2399A for ; Sun, 27 Sep 2020 07:54:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601193246; bh=FExBk8zsN+Ua6IDq4ZCBhvfYVoagS100fvkfTV2FMnM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=XG2jc1peYOyeqx6T91t15Ky+nNL36WOr+jcX9CMrRSS1AYHmtl/Hc1rQcRYOd0wd4 Q4H8ku9/kEz0HnOv1/NnIE0Gg+daUJsLnAWbNE+4xyeJnd8e9AUQg+R0w6NwBefBRH vpOzoiUM5kMHQwamH7WOmyKz5kCwZ927CsPEc1ig= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727263AbgI0HyG (ORCPT ); Sun, 27 Sep 2020 03:54:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:36070 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726840AbgI0HyG (ORCPT ); Sun, 27 Sep 2020 03:54:06 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0558523998; Sun, 27 Sep 2020 07:54:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601193244; bh=FExBk8zsN+Ua6IDq4ZCBhvfYVoagS100fvkfTV2FMnM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UdlekJ0oMY7sUTK2cmaXNkekV8FOi9RmlzJM9krjblQFsS9IzteGZarqbbbBDaRg4 UKeUUPMVtooDkVq2lTCgtUUedNlVzQtR24tgXlttG+IQpxdHlJX9p6tBEGgpOqvcM+ C2IXC6n7l9N+kk0g36JxJis083McMZtg3ECc+KNY= Date: Sun, 27 Sep 2020 09:54:01 +0200 From: Greg KH To: Xu Yilun Cc: Moritz Fischer , linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org, trix@redhat.com, lgoncalv@redhat.com, hao.wu@intel.com Subject: Re: [PATCH v3 1/5] fpga: dfl: rename the bus type "dfl" to "fpga-dfl" Message-ID: <20200927075401.GA748141@kroah.com> References: <1600966801-30586-1-git-send-email-yilun.xu@intel.com> <1600966801-30586-2-git-send-email-yilun.xu@intel.com> <20200924172700.GA79736@archbook> <20200926022346.GA5623@yilunxu-OptiPlex-7050> <20200926060913.GA637197@kroah.com> <20200926192219.GA18625@epycbox.lan> <20200927055108.GA701198@kroah.com> <20200927073754.GB16433@yilunxu-OptiPlex-7050> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200927073754.GB16433@yilunxu-OptiPlex-7050> Precedence: bulk List-ID: X-Mailing-List: linux-fpga@vger.kernel.org On Sun, Sep 27, 2020 at 03:37:54PM +0800, Xu Yilun wrote: > Hi Greg, > > On Sun, Sep 27, 2020 at 07:51:08AM +0200, Greg KH wrote: > > On Sat, Sep 26, 2020 at 12:22:19PM -0700, Moritz Fischer wrote: > > > Hi Greg, > > > > > > On Sat, Sep 26, 2020 at 08:09:13AM +0200, Greg KH wrote: > > > > On Sat, Sep 26, 2020 at 10:23:46AM +0800, Xu Yilun wrote: > > > > > Hi greg, > > > > > > > > > > About the bus naming, I summarized some questions we've discussed to check > > > > > with you. See inline. > > > > > > > > > > On Thu, Sep 24, 2020 at 10:27:00AM -0700, Moritz Fischer wrote: > > > > > > Hi Xu, > > > > > > > > > > > > On Fri, Sep 25, 2020 at 12:59:57AM +0800, Xu Yilun wrote: > > > > > > > Now the DFL device drivers could be made as independent modules and put > > > > > > > in different subsystems according to their functionalities. So the name > > > > > > > should be descriptive and unique in the whole kernel. > > > > > > > > > > > > > > The patch changes the naming of dfl bus related structures, functions, > > > > > > > APIs and documentations. > > > > > > > > > > > > > > Signed-off-by: Xu Yilun > > > > > > > --- > > > > > > > Documentation/ABI/testing/sysfs-bus-dfl | 15 -- > > > > > > > Documentation/ABI/testing/sysfs-bus-fpga-dfl | 15 ++ > > > > > > > MAINTAINERS | 2 +- > > > > > > > drivers/fpga/dfl.c | 254 ++++++++++++++------------- > > > > > > > drivers/fpga/dfl.h | 77 ++++---- > > > > > > > 5 files changed, 184 insertions(+), 179 deletions(-) > > > > > > > delete mode 100644 Documentation/ABI/testing/sysfs-bus-dfl > > > > > > > create mode 100644 Documentation/ABI/testing/sysfs-bus-fpga-dfl > > > > > > > > > > > > > > diff --git a/Documentation/ABI/testing/sysfs-bus-dfl b/Documentation/ABI/testing/sysfs-bus-dfl > > > > > > > deleted file mode 100644 > > > > > > > index 23543be..0000000 > > > > > > > --- a/Documentation/ABI/testing/sysfs-bus-dfl > > > > > > > +++ /dev/null > > > > > > > @@ -1,15 +0,0 @@ > > > > > > > -What: /sys/bus/dfl/devices/dfl_dev.X/type > > > > > > > -Date: Aug 2020 > > > > > > > -KernelVersion: 5.10 > > > > > > > -Contact: Xu Yilun > > > > > > > -Description: Read-only. It returns type of DFL FIU of the device. Now DFL > > > > > > > - supports 2 FIU types, 0 for FME, 1 for PORT. > > > > > > > - Format: 0x%x > > > > > > > - > > > > > > > -What: /sys/bus/dfl/devices/dfl_dev.X/feature_id > > > > > > > -Date: Aug 2020 > > > > > > > -KernelVersion: 5.10 > > > > > > > -Contact: Xu Yilun > > > > > > > -Description: Read-only. It returns feature identifier local to its DFL FIU > > > > > > > - type. > > > > > > > - Format: 0x%x > > > > > > > > > > > > You're changing userland facing ABI. I think that's something to avoid, > > > > > > please check with Greg on the rules since this hasn't been in a release yet. > > > > > > > > > > > > > > > > I'm going to change the name of bus stuff for other subsystems, to be > > > > > aligned, I also consider change the bus_type.name and dfl dev_name. But > > > > > it will cause the changing of user ABIs. No user case for these user ABI > > > > > now cause they are just queued, is it good I change them? > > > > > > > > Why change the user name here? No need for that, right? Unless you > > > > really want to, and think that no one will notice. If so, fine, change > > > > them :) > > > > > > Let's leave it as is -- An FPGA is one possible implementation and as for > > > other buses, you wouldn't call it fpga-usb or usb-fpga just because the > > > USB bus is implemented in an FPGA if it behaves like a normal USB bus. > > > Having an ASIC based DFL bus show up under dfl-fpga / fpga-dfl in sysfs > > > would be super confusing. > > > > > > > > It is mentioned that although Device Feature List is introduced in FPGA, > > > > > but it doesn't limit the usage in FPGA only. It's just a method to > > > > > discover features from a device, for sure it can be extended and used > > > > > in other devices too. So it can be bigger namespace than FPGA. Like in > > > > > our existing code, we picked dfl_fpga (DFL based FPGA) for uapi (ioctl) > > > > > and internal functions. This is suggested by Alan (The previous FPGA > > > > > maintainer). It's possible to have "DFL based XXX" in the future, even > > > > > currently only FPGA uses DFL. This is the reason we thought just "dfl" > > > > > in the whole kernel space is OK. > > > > > So, is there a chance we keep the "dfl" naming in the whole kernel? > > > > > > > > No one knows what "DFL" is, and odds are, if a different subsystem wants > > > > to use it, they will have their own variant, right? > > DFL is a method to discover devices. If a different subsystem (e.g. ASIC based > DFL bus) want to use DFL and follows the DFL spec, they could just use the DFL > stuff for enumeration, no need to have new variants. > > > > > > > > > And why didn't you all use device tree? How did this sneak in past > > > > everyone? > > > > > > DFL is a pretty efficient implementation in terms of resource > > > utilization on the FPGA end (a couple of registers / memories) vs > > > several kilobytes of memory for a device-tree blob. > > > > > > The hardware using DFL to describe its internal structure exists in the > > > form of deployed accelerator cards and telling all its users to go and > > > change their hardware design would be feasible -- If you think about an > > > FPGA as a (albeit reconfigurable) ASIC you wouldn't go and tell people > > > to redesign their ASIC to use Device-Tree? :) > > > > > > I'm not sure where the 'sneaking in' anything comes from. It's been > > > reviewed on the list (and by yourself back then). If you feel any of > > > this wasn't kosher, let's talk about it, to make sure it doesn't happen > > > again. > > > > I can't remember reviewing it, sorry, too many patches, I probably was > > only worrying about functionality issues, not what the code actually did > > :) > > > > So it's fine, just a surprise to me, no big deal. > > I'm glad that we made it clear. And the bus name & user APIs cound be > kept as "dfl". So I assume the name "dfl" is OK to be used and could > be recognized by people out of FPGA domain, is it? > > If so, I still want to keep the name "dfl_device_id" in mod_devicetable.h > as well. No, this is specific to the fpga subsystem, right? So please put fpga in the name. > We want to keep the device id name of the bus aligned with the > bus name. And it would be confusing as well if a driver for ASIC based > DFL device uses the "dfl_fpga_device_id" structure. Do we have that in the kernel today? thanks, greg "naming is hard" k-h