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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 62122C7EE23 for ; Wed, 7 Jun 2023 08:56:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239645AbjFGI4g (ORCPT ); Wed, 7 Jun 2023 04:56:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54634 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239623AbjFGI4M (ORCPT ); Wed, 7 Jun 2023 04:56:12 -0400 Received: from mail-ed1-x535.google.com (mail-ed1-x535.google.com [IPv6:2a00:1450:4864:20::535]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7C6F81BF7 for ; Wed, 7 Jun 2023 01:55:13 -0700 (PDT) Received: by mail-ed1-x535.google.com with SMTP id 4fb4d7f45d1cf-516a008e495so369611a12.1 for ; Wed, 07 Jun 2023 01:55:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1686128112; x=1688720112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=RTpA5qOAPRS8MQZfyN8Ss9cXLKE3reuQWNe17eVOs98=; b=D2ESwCvV3EMJ4Ca9Xo0YrNr2h8zDu3w8UAFRDTvjKd+CzOHysYAMrUv95WmgXW6pef PsKk6OT+GE3LhG59KbziqQ8SX2zQaEPT9u8GVDR84WIwdNAJaeEZI0k91AdVnjG4fkba 7QfIE+0YEtfGCqwMJjmHD0uUn7sG3yGccZKVA9w7gvuWa2pSa7UzCkUG/q57UumGb1EA 4OKi4guQJOqGhlKfXqujVgAzpzyCQ7hJotGxoUFQ9FHVd4N13KRLYrRg+JJE1C5Pxxon yqRiF+kOeMILJ7ArRRRzkzEFaxvUjTteQsnxlZPRwwLMcnLuFClt6rOtK1yjIsDrIlmd ftfw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1686128112; x=1688720112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=RTpA5qOAPRS8MQZfyN8Ss9cXLKE3reuQWNe17eVOs98=; b=QVcWM1/omvUwn1J2k3Q2Vyiw0EI8CUtsl6htVqHNctDVTBJTnxPpnaKEWJmIiOJZzD Z9F9eYs7mPCanD88Sor1A1NjMDQ9NFj8kY4S2Khbw+lTU0L08sJtPlGmkEdZTj52DuX0 Rpx6j8pcSJDVwoANMzM+gq46bOFW9lEuoeBEMPIsKG4gkKOyKbNbtC7pgpn42zm1ToCX ONIv5eXUUpumBdmT6rOh9zPex9ehOaCPiqw9zpfAluuAF3rzzhb3Rx3b+XlJKsqgmlL9 eQhB300uycYCmSkuco9phbf/AZpbJMfadqAT/HEk0/kJ/Lu/gA292Sr4AJ7zTK3lqAHo jpeg== X-Gm-Message-State: AC+VfDzhovEBlFFMMLDT3uK+RjJf76M39N4Ebol0/jTa9Y6CDH9g/lkl rc26vu16GknyAOtQ+/krfGtyUA== X-Google-Smtp-Source: ACHHUZ68EljsPgkNMfLt/pjzYCbcf3rch3Eqf0hQ739bCBHvP3l1XP1YD46PoScoXp1Rg3YgbqRIWg== X-Received: by 2002:aa7:c59a:0:b0:514:9e47:4319 with SMTP id g26-20020aa7c59a000000b005149e474319mr4990483edq.5.1686128111991; Wed, 07 Jun 2023 01:55:11 -0700 (PDT) Received: from [192.168.1.20] ([178.197.219.26]) by smtp.gmail.com with ESMTPSA id u6-20020aa7d0c6000000b0050488d1d376sm5951735edo.0.2023.06.07.01.55.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 07 Jun 2023 01:55:11 -0700 (PDT) Message-ID: Date: Wed, 7 Jun 2023 10:55:08 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.2 Subject: Re: [v5 3/5] dt-bindings: mfd: Add aspeed pwm-tach binding Content-Language: en-US To: Billy Tsai , Patrick Williams Cc: "jdelvare@suse.com" , "linux@roeck-us.net" , "robh+dt@kernel.org" , "krzysztof.kozlowski+dt@linaro.org" , "joel@jms.id.au" , "andrew@aj.id.au" , "lee@kernel.org" , "thierry.reding@gmail.com" , "u.kleine-koenig@pengutronix.de" , "corbet@lwn.net" , "p.zabel@pengutronix.de" , "linux-hwmon@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-aspeed@lists.ozlabs.org" , "linux-kernel@vger.kernel.org" , "linux-pwm@vger.kernel.org" , "linux-doc@vger.kernel.org" References: <20230606094535.5388-1-billy_tsai@aspeedtech.com> <20230606094535.5388-4-billy_tsai@aspeedtech.com> <35bf0a69-bcf6-ae35-eb3c-e74cfcf9c571@linaro.org> From: Krzysztof Kozlowski In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/06/2023 08:26, Billy Tsai wrote: > >> > >> He felt what he was trying to accomplish met the documented > >> expectations. Are there some changes that need to be done in mfd.txt to > >> further clarify when to use it and when not to? > > > I think mfd.txt clearly states: > > "For more complex devices, when the nexus driver has to > > probe registers to figure out what child devices exist etc, this should > > not be used. In the latter case the child devices will be determined by > > the operating system." > > About the mfd: > For our pwm and tach devices, there is no need to check/apply any hardware register from parent to determine child’s existence or functional. > They don’t have any dependency on the parent node. In fact, it doesn’t require a specific driver to bind with the "aspeed,ast2600-pwm-tach" label. Their purpose is solely to share the same clock, reset phandle and base address. The main reason for using simple-mfd in this case is because these two independent devices share the same base address. Actually one more thoughts. I have doubt that you have two independent devices. If you share the clock, reset line and register address space, this means *you do not have two independent devices*. You have most likely only one device. Best regards, Krzysztof