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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 AB5EBC46469 for ; Wed, 12 Sep 2018 12:14:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5D68620882 for ; Wed, 12 Sep 2018 12:14:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5D68620882 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bootlin.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726945AbeILRSs (ORCPT ); Wed, 12 Sep 2018 13:18:48 -0400 Received: from mail.bootlin.com ([62.4.15.54]:51303 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726359AbeILRSr (ORCPT ); Wed, 12 Sep 2018 13:18:47 -0400 Received: by mail.bootlin.com (Postfix, from userid 110) id 0F4E320720; Wed, 12 Sep 2018 14:14:31 +0200 (CEST) Received: from localhost (242.171.71.37.rev.sfr.net [37.71.171.242]) by mail.bootlin.com (Postfix) with ESMTPSA id D8364203DA; Wed, 12 Sep 2018 14:14:20 +0200 (CEST) Date: Wed, 12 Sep 2018 14:14:20 +0200 From: Alexandre Belloni To: Lee Jones Cc: Geert Uytterhoeven , radu_nicolae.pirea@upb.ro, Rob Herring , Mark Rutland , Nicolas Ferre , Greg KH , Mark Brown , Jiri Slaby , Richard Genoud , "David S. Miller" , Mauro Carvalho Chehab , Andrew Morton , Arnd Bergmann , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , Linux ARM , Linux Kernel Mailing List , "open list:SERIAL DRIVERS" , linux-spi Subject: Re: [PATCH v12 0/6] Driver for at91 usart in spi mode Message-ID: <20180912121420.GE2760@piout.net> References: <20180911181838.GI4185@dell> <20180911185839.GA25212@piout.net> <20180911224418.GK4185@dell> <20180911225440.GL4185@dell> <20180912073355.GB2557@piout.net> <20180912084143.GN4185@dell> <20180912105407.GR4185@dell> <20180912111757.GC2760@piout.net> <20180912114352.GT4185@dell> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180912114352.GT4185@dell> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/09/2018 12:43:52+0100, Lee Jones wrote: > > > But ... we can't have it both ways. *Either* it's a true MFD, in > > > which case it can/should have 2 separate compatible strings which can > > > be specified directly from the DT. *Or* it's not an MFD. In the > > > latter case, which I think we're all agreeing on (else we'd have 2 > > > compatible strings), MFD is not the place to handle this (my original > > > point). > > > > > > > If that is what bothers you, then let's move it out of mfd. > > As I've already mentioned. I don't just want it moved out of MFD and > shoved somewhere else. My aim is to fix this properly. > If it is out of MFD, then I'm not sure why you would care too much about it as you won't be maintaining that code. And I still this what was done was correct but I'm open to test what you suggest. > > > So ... this is a USART device which can do SPI, right? > > > > > > My current thinking is that; as this is a USART device first & > > > foremost, the USART should be probed in the first instance regardless, > > > then if SPI mode is specified it (the USART driver) registers the SPI > > > platform driver (as MFD does currently) and exits gracefully, allowing > > > the SPI driver to take over. > > > > > > Spanner in the works: is it physically possible to change the mode at > > > run-time? :s > > > > Yes it is possible but on Linux that will not happen without probing > > the drivers again. > > Not sure I understand what you mean. > I was just commenting on changing the mode at runtime. > I'm suggesting that you use the same platform_* interfaces MFD uses to > register the SPI driver if SPI mode has been selected. Only do so > from the appropriate driver i.e. USART. > Yeah, I understood that but I didn't comment because I'm not sure this will work yet. -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com