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=-0.9 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 E9C2AC433E1 for ; Fri, 5 Jun 2020 20:07:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C324C206FA for ; Fri, 5 Jun 2020 20:07:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=walle.cc header.i=@walle.cc header.b="OuBQyumV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728257AbgFEUHl (ORCPT ); Fri, 5 Jun 2020 16:07:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47292 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728227AbgFEUHk (ORCPT ); Fri, 5 Jun 2020 16:07:40 -0400 Received: from ssl.serverraum.org (ssl.serverraum.org [IPv6:2a01:4f8:151:8464::1:2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 86799C08C5C3; Fri, 5 Jun 2020 13:07:39 -0700 (PDT) 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 C7B7222FEB; Fri, 5 Jun 2020 22:07:36 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=walle.cc; s=mail2016061301; t=1591387657; 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=A4yi/Grhaf0w4jjGNDMnsTZ5HJKkIfL4Ymq6vlFIb8I=; b=OuBQyumVx9fvWq152YNCm2zk5nOR6UzVoQFWmfvSoHap0daT70FokziRiSbd6uS36mmPq6 G+e8cV1FzWm9bwj7zpeF8fVaVmGgJnv9KD/GT5DtDfSlaIe9MSW8xvNitMyQkuNc0sFibr gIo1iXnMpABriffMl0K69T6+nevu00I= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Fri, 05 Jun 2020 22:07:36 +0200 From: Michael Walle To: Mark Brown Cc: Lee Jones , linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-pwm@vger.kernel.org, linux-watchdog@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Linus Walleij , Bartosz Golaszewski , Rob Herring , Jean Delvare , Guenter Roeck , Thierry Reding , =?UTF-8?Q?Uwe_Kleine-K=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: <20200605105026.GC5413@sirena.org.uk> References: <20200604211039.12689-1-michael@walle.cc> <20200604211039.12689-3-michael@walle.cc> <20200605065709.GD3714@dell> <20200605105026.GC5413@sirena.org.uk> User-Agent: Roundcube Webmail/1.4.4 Message-ID: X-Sender: michael@walle.cc Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Am 2020-06-05 12:50, schrieb Mark Brown: > On Fri, Jun 05, 2020 at 07:57:09AM +0100, Lee Jones wrote: >> On Thu, 04 Jun 2020, Michael Walle wrote: > >> > + sl28cpld->regmap = devm_regmap_init_i2c(i2c, &sl28cpld_regmap_config); >> > + if (IS_ERR(sl28cpld->regmap)) >> > + return PTR_ERR(sl28cpld->regmap); > >> This is now a shared memory allocator and not an MFD at all. > >> I'm clamping down on these type of drivers! > >> Please find a better way to accomplish this. > > What is the concern with this? Looking at the patch I'm guessing the > concern would be that the driver isn't instantiating any MFD children > and instead requiring them to be put in the DT? > >> Potentially using "simple-mfd" and "simple-regmap". > >> The former already exists and does what you want. The latter doesn't >> yet exist, but could solve your and lots of other contributor's >> issues. > > I have no idea what you are thinking of when you say "simple-regmap" so > it is difficult to comment. I guess, Lee is suggesting to be able to create a regmap instance via device tree (and populate its child nodes?). Like compatible = "syscon", "simple-mfd"; but for any regmap, not just MMIO. But, there is more in my driver: (1) there is a version check (2) there is another function for which there is no suitable linux subsystem I'm aware of and thus which I'd like to us sysfs attributes for: This controller supports 16 non-volatile configuration bits. (this is still TBD) I don't see what is different between this driver and for example the gateworks-gsc.c. Just that mine doesn't use a global register set, but local offsets and a base for each component. From a hardware perspective its one device behind an I2C address providing different functions across multiple driver subsystems. Actually, I've tried to remove the devm_of_platform_populate() and instead added the "simple-mfd" to my mfd node: compatible = "kontron,sl28cpld-r1", "simple-mfd"; I guess that doesn't work because the device is below the i2c bus? -- -michael