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 AE9A9C5479D for ; Wed, 11 Jan 2023 19:49:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232212AbjAKTtM (ORCPT ); Wed, 11 Jan 2023 14:49:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49378 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232361AbjAKTsU (ORCPT ); Wed, 11 Jan 2023 14:48:20 -0500 Received: from mail-pg1-x52e.google.com (mail-pg1-x52e.google.com [IPv6:2607:f8b0:4864:20::52e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7323F3A2 for ; Wed, 11 Jan 2023 11:48:19 -0800 (PST) Received: by mail-pg1-x52e.google.com with SMTP id f3so11290136pgc.2 for ; Wed, 11 Jan 2023 11:48:19 -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=VUD7VWxsTLdXOfiM9+k/eeXf3wS9oa0S7XpNc1NyWQ0=; b=D25N+VquKY3lYrOahotIar0GIfMWBMlxhLB6DNodNuIcPk6tjlnOsZyHM7gVVjKFBk XFWuskozCecvsXi1JRB4d3iJbQnMGYVIko8/+aK0eQdneOmaYuZdtf2R9CIWKlUSKDlf 3lmohR297w6S8DctPE2h+bvktoKNLu3ZFsBqo= 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=VUD7VWxsTLdXOfiM9+k/eeXf3wS9oa0S7XpNc1NyWQ0=; b=Y8XzDoQJVC1Pucd9+Fru4U33Gke/knHKF5V3MDOqN41nSUgJxrQ0HQsMSR91M97r33 EtkOdxGQqjo3qUlQ+POXYxfv13VgaPmv4chlsbZhmhG95XkWrE+PlVdfZGgcjzUYDjpK qxnfyF+fVMVRATTXdlEExKM24AOpfMDLQKKTSeF6OnuhTu5OOiZpD3ndrm13SPbpCPyV FbVY5uFfEdGKqU95zdy6fMdgQZN9EhByLSlNLdPY/92GVtMuIP/UIVDOxg61coDpJddx hV4ptnOlUjOdDiU2f1mNKEkRp5ysEuYXkW4KlHsB1JTTLhfNEHgHbbuhBrPz04CJbNBi 8oCQ== X-Gm-Message-State: AFqh2koAbpGJDAbXbJuwOYGE/wi9GaVk0vMWyxPMGVJHXaqG8WUf71Z3 GyGvnLm5ViF+iQC9nS3cXHQYbyH2G20q6u6O/0PWVx4KMc/pg6YoSjkdoRt9qmD/lhvDkukuB2Z 43TRALpgUyQXHrTej2Ud2T7taT3YXaQLWmcRFEKW4wACjOzEWqhkWWbHrRXZDZ6twZyBHqnFMne 51vYoRFyQnkSc= X-Google-Smtp-Source: AMrXdXu70lr36Umvn0O72GVI5dkgMQUBwczSrT6+XK7TiZZGrY3ymN7j3qMyMsYvs6V7/JfUSn7RUw== X-Received: by 2002:a05:6a00:72a:b0:57d:56f1:6ae7 with SMTP id 10-20020a056a00072a00b0057d56f16ae7mr62388860pfm.33.1673466498307; Wed, 11 Jan 2023 11:48:18 -0800 (PST) Received: from bcacpedev-irv-3.lvn.broadcom.net ([192.19.161.250]) by smtp.gmail.com with ESMTPSA id u127-20020a626085000000b00580fb018e4bsm6607563pfb.211.2023.01.11.11.48.16 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 11 Jan 2023 11:48:17 -0800 (PST) Subject: Re: [PATCH 03/16] dt-bindings: spi: Add spi peripheral specific property To: Mark Brown Cc: Rob Herring , 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> <6720e3a4-dbbb-f490-98db-511a52b9a2ab@broadcom.com> From: William Zhang Message-ID: Date: Wed, 11 Jan 2023 11:48:16 -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="000000000000366af905f2024872" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --000000000000366af905f2024872 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit On 01/10/2023 02:01 PM, Mark Brown wrote: > On Mon, Jan 09, 2023 at 12:18:09PM -0800, William Zhang wrote: > >> This setting is set per spi message for particular chip select of the device >> when starting the message through bcm63xx_hsspi_set_clk function and restore >> to default(clock gating) when message is done through >> bcm63xx_hsspi_restore_clk_gate. > > In that case I am extremely confused about what the feature is supposed > to do. The description says: > > + 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. > > > which to me sounds like the clock should never be turned off and instead > left running at all times. Switching back to clock gating after sending > the message doesn't seem to correspond to the above at all, the message > being done would normally also be the point at which chip select is > deasserted. > This feature is used by our voice team and as far I can tell, it is used to keep clock running between the transfers within the same message. But now that we have prepend mode to combine to one transfer or dummy workaround to keep cs always active between transfers, this indeed does not seems right. I will have to talk to the voice team why this is still needed and get back here. --000000000000366af905f2024872 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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