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 B148FC46467 for ; Sat, 7 Jan 2023 03:36:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231335AbjAGDgF (ORCPT ); Fri, 6 Jan 2023 22:36:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39112 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229521AbjAGDgE (ORCPT ); Fri, 6 Jan 2023 22:36:04 -0500 Received: from mail-qt1-x836.google.com (mail-qt1-x836.google.com [IPv6:2607:f8b0:4864:20::836]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F1A26C07 for ; Fri, 6 Jan 2023 19:36:02 -0800 (PST) Received: by mail-qt1-x836.google.com with SMTP id v14so3825004qtq.3 for ; Fri, 06 Jan 2023 19:36:02 -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=8Cs/5+6LA9OtaicfH5IQoAfbsUYW0y6F32TrdTRPZyU=; b=cf2D0KGrzTj0ad6LuOnX8pW8FixiroxbmrCRgm4lTqpHu2KT9KwSaDdYvrfCe/bTwy AuZlNXYPkR1kw+oFE4cz4DtJDoOKZlrW5gDjSyXP8/kbbdzD6oxqPw8z021mG92hjtLO GoH1qobPEKL4Vhu0p28J4ewC0JwjnEPynOVkQ= 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=8Cs/5+6LA9OtaicfH5IQoAfbsUYW0y6F32TrdTRPZyU=; b=xAt3QmUTfA2RJDyq1K6hN8czw8AFhU4pRwUsvOL+h4Zecvvsd2tCFd2vBFRUROrE1T v7YcdfUosb6cIsFcTyFeFfNdmV2AAzgsrcFVq3/HW6Dq7wPJzKmNPoOYM4ZpI6eFJB6X 7nrOF34nj1RU+UCfsrpYFPfzrIaZRO+u8iiAv89GGGx/m1MJVBdELWXLY4wSPLcv7Cv9 NwbYjA5+uhCCfPTk83wkfoEEn4troVGlWbMu3qVCsORO+Z172CXgfubmrcLkyiPb9SF4 1BCluZPnpCt2HnyJCerEl48EWuAwuN3hJCg5UpxwXHvgpH+Ogn8jXANYBcKYpI4i33Lj qykQ== X-Gm-Message-State: AFqh2krOJiH/M2bzDWqBCUpvPG1xF4dXx/f+ei8/LPPRLUnXg92WHmqL P/iEBwU/Dul9tP67GFSmCutx1w== X-Google-Smtp-Source: AMrXdXteuvYOh0s0azL7/PlZxuOlbvJoft3qH/CyIS1dgzSVUOCYFVJ6QCRUpF4sMJJZyUzgCd0e+w== X-Received: by 2002:ac8:7551:0:b0:3a7:f46b:7a82 with SMTP id b17-20020ac87551000000b003a7f46b7a82mr74882152qtr.21.1673062562030; Fri, 06 Jan 2023 19:36:02 -0800 (PST) Received: from bcacpedev-irv-3.lvn.broadcom.net ([192.19.161.250]) by smtp.gmail.com with ESMTPSA id t13-20020ac8738d000000b003434d3b5938sm1417743qtp.2.2023.01.06.19.36.00 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 06 Jan 2023 19:36:01 -0800 (PST) Subject: Re: [PATCH 07/16] spi: bcm63xx-hsspi: Add polling mode support To: Mark Brown Cc: 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, linux-kernel@vger.kernel.org References: <20230106200809.330769-1-william.zhang@broadcom.com> <20230106200809.330769-8-william.zhang@broadcom.com> From: William Zhang Message-ID: Date: Fri, 6 Jan 2023 19:35:59 -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="000000000000b74b4105f1a43bd6" Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org --000000000000b74b4105f1a43bd6 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit On 01/06/2023 01:47 PM, Mark Brown wrote: > On Fri, Jan 06, 2023 at 12:07:59PM -0800, William Zhang wrote: > >> Polling mode provides better throughput in general by avoiding the >> interrupt overhead as the maximum data size one interrupt can handle is >> only 512 bytes. > >> When interrupt is not defined in the HSSPI dts node, driver switches to >> polling mode for controller SPI message processing. Also add driver >> banner message when the driver is loaded successfully. > > This should not be something the user selects via the DT, if the polling > mode is better then the driver should just use it regardless of there > being an interrupt wired up. Generally there's some point at which the > benefits of polling become minimal (and the costs more impactful) but if > the DMA setup is as bad as it sounds then the driver should just ignore > the interrupt. > I agree but this is more for backward compatibility as the original driver uses interrupt to work with MIPS based SoC and I do not want to change that behavior. For newer devices I added, they work in polling mode by default with the dts I supplied. IMHO it is also good to have this fallback option to use interrupt in case user is sensitive to cpu usage. --000000000000b74b4105f1a43bd6 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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