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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 83CE2C433E0 for ; Wed, 10 Jun 2020 07:49:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 635762064C for ; Wed, 10 Jun 2020 07:49:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=walle.cc header.i=@walle.cc header.b="WoEXRz5O" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726570AbgFJHtJ (ORCPT ); Wed, 10 Jun 2020 03:49:09 -0400 Received: from ssl.serverraum.org ([176.9.125.105]:39381 "EHLO ssl.serverraum.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726105AbgFJHtJ (ORCPT ); Wed, 10 Jun 2020 03:49:09 -0400 Received: from ssl.serverraum.org (web.serverraum.org [172.16.0.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ssl.serverraum.org (Postfix) with ESMTPSA id 1A02022FAC; Wed, 10 Jun 2020 09:49:04 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=walle.cc; s=mail2016061301; t=1591775344; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EpiWQe7sIJRbI+UfNTOW4odZUYl2nUaDudurz82UFR4=; b=WoEXRz5Ol7yHvA4TIamouQM2IQMbMH2HE/Qr6GVUTJt9HQPASS0WLM+XW8xImuPncHHkVE gqUr1OWarLyGqYIrwQgyBJlmXzmhVALtKvHmFIfqlPJDI30cHCG+tiR3VcbPYTHydnfr3o jIs0QOf9YOPE23Flqsw8nBaumSkKuNI= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 10 Jun 2020 09:49:04 +0200 From: Michael Walle To: Lee Jones Cc: Andy Shevchenko , Ranjani Sridharan , david.m.ertman@intel.com, shiraz.saleem@intel.com, Rob Herring , Mark Brown , "open list:GPIO SUBSYSTEM" , devicetree , Linux Kernel Mailing List , linux-hwmon@vger.kernel.org, linux-pwm@vger.kernel.org, linux-watchdog@vger.kernel.org, linux-arm Mailing List , Linus Walleij , Bartosz Golaszewski , Jean Delvare , Guenter Roeck , Thierry Reding , =?UTF-8?Q?Uwe_Kleine-K?= =?UTF-8?Q?=C3=B6nig?= , Wim Van Sebroeck , Shawn Guo , Li Yang , Thomas Gleixner , Jason Cooper , Marc Zyngier , Greg Kroah-Hartman , Andy Shevchenko Subject: Re: [PATCH v4 02/11] mfd: Add support for Kontron sl28cpld management controller In-Reply-To: <20200610071940.GS4106@dell> References: <7d7feb374cbf5a587dc1ce65fc3ad672@walle.cc> <20200608185651.GD4106@dell> <32231f26f7028d62aeda8fdb3364faf1@walle.cc> <20200609064735.GH4106@dell> <32287ac0488f7cbd5a7d1259c284e554@walle.cc> <20200609151941.GM4106@dell> <95e6ec9bbdf6af7a9ff9c31786f743f2@walle.cc> <20200609194505.GQ4106@dell> <3a6931248f0efcaf8efbb5425a9bd833@walle.cc> <20200610071940.GS4106@dell> User-Agent: Roundcube Webmail/1.4.4 Message-ID: X-Sender: michael@walle.cc Sender: linux-watchdog-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org Am 2020-06-10 09:19, schrieb Lee Jones: > On Wed, 10 Jun 2020, Michael Walle wrote: >> Am 2020-06-09 21:45, schrieb Lee Jones: >> > On Tue, 09 Jun 2020, Michael Walle wrote: >> > > > We do not need a 'simple-regmap' solution for your use-case. >> > > > >> > > > Since your device's registers are segregated, just split up the >> > > > register map and allocate each sub-device with it's own slice. >> > > >> > > I don't get it, could you make a device tree example for my >> > > use-case? (see also above) >> > >> > &i2cbus { >> > mfd-device@10 { >> > compatible = "simple-mfd"; >> > reg = <10>; >> > >> > sub-device@10 { >> > compatible = "vendor,sub-device"; >> > reg = <10>; >> > }; >> > }; >> > >> > The Regmap config would be present in each of the child devices. >> > >> > Each child device would call devm_regmap_init_i2c() in .probe(). >> >> Ah, I see. If I'm not wrong, this still means to create an i2c >> device driver with the name "simple-mfd". > > Yes, it does. > >> Besides that, I don't like this, because: >> - Rob already expressed its concerns with "simple-mfd" and so on. > > Where did this take place? I'd like to read up on this. In this thread: https://lore.kernel.org/linux-devicetree/20200604211039.12689-1-michael@walle.cc/T/#m16fdba5962069e7cd4aa817582ee358c9fe2ecbf > >> - you need to duplicate the config in each sub device > > You can have a share a single config. > >> - which also means you are restricting the sub devices to be >> i2c only (unless you implement and duplicate other regmap configs, >> too). For this driver, SPI and MMIO may be viable options. > > You could also have a shared implementation to choose between different > busses. Then what is the difference between to have this shared config in the parent driver only and use the functions which are already there, i.e. dev_get_regmap(parent). But see, below, I'll wait with what you're coming up. > >> Thus, I'd rather implement a simple-mfd.c which implement a common >> I2C driver for now and populate its children using >> devm_of_platform_populate(). This could be extended to support other >> type of regmaps like SPI in the future. >> >> Also some MFD drivers could be moved to this, a likely candidate is >> the smsc-ece1099.c. Although I don't really understand its purpose, >> if don't have CONFIG_OF. >> >> Judging from the existing code, this simple-mfd.c wouldn't just be >> "a list of compatible" strings but also additional quirks and tweaks >> for particular devices in this list. > > Hold off on the simple-mfd.c idea, as I'm not taken by it yet and > wouldn't want you to waste your time. I have another idea which would > help. Give me a few days to put something together. Sure. I'm just glad there is now a discussion about this issue. -michael