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 76F8BC61DB3 for ; Mon, 9 Jan 2023 08:06:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235078AbjAIIGr (ORCPT ); Mon, 9 Jan 2023 03:06:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60232 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236489AbjAIIGb (ORCPT ); Mon, 9 Jan 2023 03:06:31 -0500 Received: from mail-pl1-x62d.google.com (mail-pl1-x62d.google.com [IPv6:2607:f8b0:4864:20::62d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 98794E74 for ; Mon, 9 Jan 2023 00:06:16 -0800 (PST) Received: by mail-pl1-x62d.google.com with SMTP id y1so8690080plb.2 for ; Mon, 09 Jan 2023 00:06:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; h=in-reply-to:mime-version:user-agent:date:message-id:from:references :cc:to:subject:from:to:cc:subject:date:message-id:reply-to; bh=y/q3Gtxs+CTN9LI/ZMx7RJ7shRCMSk/GuBPxHGnvCos=; b=BJKJxrid9aWM7vf4PhMpyLnIBhxD50JWJMIiXHMC7peGj1tp+bhIginEDFpBw3ymaz VDb5L/qFeQdylwjiPE9UYFqoYpEIO5t0GQfnobEPzB1BB0396uLFnS3jZRgXNygEueJj Mgc3NzgzDDPe7z5eT2IJY6JCNoCWqAEJVwgXY= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:mime-version:user-agent:date:message-id:from:references :cc:to:subject:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=y/q3Gtxs+CTN9LI/ZMx7RJ7shRCMSk/GuBPxHGnvCos=; b=qX7judWmG9aTnaQCZBSe/acDFwmC9+vYTS9tq6e/8wjB33CKOxn0iVnxOUID5+iOfM zTU/cSq0Ss4PwjSJArW4BowMCP6RobsCLKpGxN8/oheUzYWYwrdXeO+hd9sV7shZjonS 6INiDgFdwY8aXsWo6hcsW2skWlNn8FuHXUYaJ5C/olqD8gefMQu9N5iAgjWwXKYVfnI1 JMZDTnsDakO219LdXPH+ZIiZm1TNKdKhbNRLGdOPwVNjQEL945wLFIAuctEcBoMQyo7r RUlxQ0FiobvTuy9kFBKzVNgkgislPy/iVnJWHUT0DRTWUX0Tw+b4/C4HfTS7hcnyvQqc T4QA== X-Gm-Message-State: AFqh2krmzgEGQlW1q0QYOTXFXlYISgro+BuKBCtnvTPzzNMddG4BxWBV MDxcQ2lc19OzCThOiqcxKwL9dYZT8J5jXcW2RYzM0TsZZ8gHSvKjj7SrjDqrsU9tDwrwPjwsQZQ zISWX00XECujDQCYlHittyq/Ekppyq8uMzc1s2wMVj+C1p1CF1gJN0rtQ19N/j5Sgw3GI0IG/lf mJmmLbdogIfaE= X-Google-Smtp-Source: AMrXdXsIK4Lt073ikFOMgmB17NircyrmMuQcuLamBcOOCCq+Liu/E8KHzCc1KrftZQwyMAavXENJvw== X-Received: by 2002:a17:902:7243:b0:189:30cd:8fa2 with SMTP id c3-20020a170902724300b0018930cd8fa2mr78495236pll.50.1673251575735; Mon, 09 Jan 2023 00:06:15 -0800 (PST) Received: from bcacpedev-irv-3.lvn.broadcom.net ([192.19.161.250]) by smtp.gmail.com with ESMTPSA id j6-20020a170902690600b00192aecb231asm5438521plk.121.2023.01.09.00.06.14 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 09 Jan 2023 00:06:15 -0800 (PST) Subject: Re: [PATCH 03/16] dt-bindings: spi: Add spi peripheral specific property To: Rob Herring Cc: Mark Brown , Linux SPI List , Broadcom Kernel List , anand.gore@broadcom.com, tomer.yacoby@broadcom.com, dan.beygelman@broadcom.com, joel.peshkin@broadcom.com, f.fainelli@gmail.com, jonas.gorski@gmail.com, kursad.oney@broadcom.com, dregan@mail.com, Krzysztof Kozlowski , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20230106200809.330769-1-william.zhang@broadcom.com> <20230106200809.330769-4-william.zhang@broadcom.com> <3ff9a7fa-25dd-701c-078e-03e47bd3c08b@broadcom.com> From: William Zhang Message-ID: <6720e3a4-dbbb-f490-98db-511a52b9a2ab@broadcom.com> Date: Mon, 9 Jan 2023 00:06:13 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-256; boundary="000000000000d17c6505f1d03de3" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --000000000000d17c6505f1d03de3 Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Hi Rob, On 01/07/2023 07:38 AM, Rob Herring wrote: > On Fri, Jan 6, 2023 at 9:27 PM William Zhang wrote: >> >> Hi Mark, >> >> On 01/06/2023 01:14 PM, Mark Brown wrote: >>> On Fri, Jan 06, 2023 at 12:07:55PM -0800, William Zhang wrote: >>> >>>> brcm,no-clk-gate is a Broadcom Broadband HS SPI controller specific >>>> property for certain SPI device such as Broadcom ISI voice daughtercard >>>> to work properly. It disables the clock gating feature when the chip >>>> select is deasserted for any device that wants to keep the clock >>>> running. >>> >>> Why would this property be Broadcom specific? Other devices could in >>> theory implement this. >>> >> It does not need to be Broadcom specific if other SoC's SPI bus >> controller support such function. I am not aware of such case but >> certainly I am no expert on other chips. I can put it in the generic >> spi-peripheral-props.yaml if that is what you suggest. >> >>>> +properties: >>>> + brcm,no-clk-gate: >>>> + $ref: /schemas/types.yaml#/definitions/flag >>>> + description: >>>> + Some SPI device such as Broadcom ISI based voice daughtercard requires SPI >>>> + clock running even when chip select is deasserted. By default the >>>> + controller turns off or gate the clock when cs is not active to save >>>> + power. This flag tells the controller driver to keep the clock running >>>> + when chip select is not active. >>> >>> This seems problematic with any host controlled chip select support... >>> >> Yes those ISI chip based voice cards do need such strange requirement >> and will not work with other controller. That is one of the reason I >> put this as Broadcom specific option. > > Keeping the clock on or not would affect all devices unless you have a > per device clock you can gate, so making this a per device flag > doesn't make sense. > This applies only to each chip select. There is only one device under each chip select. So won't impact any other devices under other cs. > If this is a requirement of the slave device, then the device's > compatible string can imply the need for this and its driver can tell > the host controller in some way. That is true but spi host controller driver reads and parses these slave device flag directly. > > Rob > --000000000000d17c6505f1d03de3 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIIQcAYJKoZIhvcNAQcCoIIQYTCCEF0CAQExDzANBglghkgBZQMEAgEFADALBgkqhkiG9w0BBwGg gg3HMIIFDTCCA/WgAwIBAgIQeEqpED+lv77edQixNJMdADANBgkqhkiG9w0BAQsFADBMMSAwHgYD VQQLExdHbG9iYWxTaWduIFJvb3QgQ0EgLSBSMzETMBEGA1UEChMKR2xvYmFsU2lnbjETMBEGA1UE AxMKR2xvYmFsU2lnbjAeFw0yMDA5MTYwMDAwMDBaFw0yODA5MTYwMDAwMDBaMFsxCzAJBgNVBAYT AkJFMRkwFwYDVQQKExBHbG9iYWxTaWduIG52LXNhMTEwLwYDVQQDEyhHbG9iYWxTaWduIEdDQyBS MyBQZXJzb25hbFNpZ24gMiBDQSAyMDIwMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA vbCmXCcsbZ/a0fRIQMBxp4gJnnyeneFYpEtNydrZZ+GeKSMdHiDgXD1UnRSIudKo+moQ6YlCOu4t rVWO/EiXfYnK7zeop26ry1RpKtogB7/O115zultAz64ydQYLe+a1e/czkALg3sgTcOOcFZTXk38e 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