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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 CC182C4361B for ; Sat, 19 Dec 2020 00:23:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 93AC123B27 for ; Sat, 19 Dec 2020 00:23:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726347AbgLSAWy (ORCPT ); Fri, 18 Dec 2020 19:22:54 -0500 Received: from relay4-d.mail.gandi.net ([217.70.183.196]:51157 "EHLO relay4-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725925AbgLSAWx (ORCPT ); Fri, 18 Dec 2020 19:22:53 -0500 X-Greylist: delayed 97350 seconds by postgrey-1.27 at vger.kernel.org; Fri, 18 Dec 2020 19:22:52 EST X-Originating-IP: 86.202.109.140 Received: from localhost (lfbn-lyo-1-13-140.w86-202.abo.wanadoo.fr [86.202.109.140]) (Authenticated sender: alexandre.belloni@bootlin.com) by relay4-d.mail.gandi.net (Postfix) with ESMTPSA id 73881E0002; Sat, 19 Dec 2020 00:22:08 +0000 (UTC) Date: Sat, 19 Dec 2020 01:22:08 +0100 From: Alexandre Belloni To: Jason Gunthorpe Cc: Mark Brown , Greg KH , Dan Williams , Pierre-Louis Bossart , alsa-devel@alsa-project.org, Kiran Patil , linux-rdma , Shiraz Saleem , Martin Habets , Liam Girdwood , Ranjani Sridharan , Fred Oh , Dave Ertman , Jakub Kicinski , Netdev , Leon Romanovsky , David Miller , Linux Kernel Mailing List , Parav Pandit , lee.jones@linaro.org Subject: Re: [resend/standalone PATCH v4] Add auxiliary bus support Message-ID: <20201219002208.GI3143569@piout.net> References: <20201218131709.GA5333@sirena.org.uk> <20201218140854.GW552508@nvidia.com> <20201218155204.GC5333@sirena.org.uk> <20201218162817.GX552508@nvidia.com> <20201218180310.GD5333@sirena.org.uk> <20201218184150.GY552508@nvidia.com> <20201218203211.GE5333@sirena.org.uk> <20201218205856.GZ552508@nvidia.com> <20201218211658.GH3143569@piout.net> <20201218233608.GA552508@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201218233608.GA552508@nvidia.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18/12/2020 19:36:08-0400, Jason Gunthorpe wrote: > On Fri, Dec 18, 2020 at 10:16:58PM +0100, Alexandre Belloni wrote: > > > But then again, what about non-enumerable devices on the PCI device? I > > feel this would exactly fit MFD. This is a collection of IPs that exist > > as standalone but in this case are grouped in a single device. > > So, if mfd had a mfd_device and a mfd bus_type then drivers would need > to have both a mfd_driver and a platform_driver to bind. Look at > something like drivers/char/tpm/tpm_tis.c to see how a multi-probe > driver is structured > > See Mark's remarks about the old of_platform_device, to explain why we > don't have a 'dt_device' today > So, what would that mfd_driver have that the platform_driver doesn't already provide? > > Note that I then have another issue because the kernel doesn't support > > irq controllers on PCI and this is exactly what my SoC has. But for now, > > I can just duplicate the irqchip driver in the MFD driver. > > I think Thomas fixed that recently on x86 at least.. > > Having to put dummy irq chip drivers in MFD anything sounds scary :| > This isn't a dummy driver it is a real irqchip, what issue is there to register an irqchip from MFD ? > > Let me point to drivers/net/ethernet/cadence/macb_pci.c which is a > > fairly recent example. It does exactly that and I'm not sure you could > > do it otherwise while still not having to duplicate most of macb_probe. > > Creating a platform_device to avoid restructuring the driver's probe > and device logic to be generic is a *really* horrible reason to use a > platform device. > Definitively but it made it in and seemed reasonable at the time it seems. I stumbled upon that a while ago because I wanted to remove platform_data support from the macb driver and this is the last user. I never got the time to tackle that. -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com