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 C719AC46467 for ; Wed, 11 Jan 2023 19:49:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235713AbjAKTtG (ORCPT ); Wed, 11 Jan 2023 14:49:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49786 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230514AbjAKTsU (ORCPT ); Wed, 11 Jan 2023 14:48:20 -0500 Received: from mail-pg1-x534.google.com (mail-pg1-x534.google.com [IPv6:2607:f8b0:4864:20::534]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 10E5620E for ; Wed, 11 Jan 2023 11:48:19 -0800 (PST) Received: by mail-pg1-x534.google.com with SMTP id d10so11258711pgm.13 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=enAhZlFkGrAGYyPjDKPsiFGN+sHjzn84LwIDmt42nLU=; b=MRw4qhgWmByobzfodVcZY17e9KBuWftxoVfdUZCIf3PIfSiY6O5Vw8UMPOoIPoFlj5 AOqNsX17DfC33uq7Ysm3+9FqwOrPfaqFdkApfNbEysfHojR5om88vtrNi/d393s04X1+ j0TWaaJI24QR8ISSIhdVNS0Yw5O7z1LT4RlH8= 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=enAhZlFkGrAGYyPjDKPsiFGN+sHjzn84LwIDmt42nLU=; b=6gAhW0OctBXCRgTJ2+DKDA2w6V5VHYnp/G1uQ3M0gN7+bIYOUHiWcoa1fDNjMYh0bx vtv3ZfDBGbMKTUvrIRYf0SBNZI/MMiUjuqBiQUj3AbGkP+VtowipVjF6hD48JRjHG19O CSgZNs6QaMHEjohuXuDwCO/L2fnwQ1ewsm4d1lORPvvzxPUVhxZOJ3jCf9Svg7UXp8GQ +Z/KmAzNT2najvMIX4IyXi/s8FkqzA+J3L/9IvvD632Xxui2dQUvO+vxUCI1AWIbv5gA CKPRwPCVXIUoMGNyhNUzEwWB4GUFw8ns2lBgQThnHZxqHRQ7op22C+8cAfB2YDJk1EMS EI2w== X-Gm-Message-State: AFqh2kremzx2anoYc5SSplSnmBEjunFMJTOrt2zMPX38MqmHA1VvNv2V RFZdLJkmOZtQBL6oVNcSakD4eg== 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="000000000000344b9205f20248a8" Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org --000000000000344b9205f20248a8 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. --000000000000344b9205f20248a8 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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