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 AA178C61DB3 for ; Mon, 9 Jan 2023 20:10:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237553AbjAIUKl (ORCPT ); Mon, 9 Jan 2023 15:10:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34866 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237264AbjAIUKh (ORCPT ); Mon, 9 Jan 2023 15:10:37 -0500 Received: from mail-pf1-x42a.google.com (mail-pf1-x42a.google.com [IPv6:2607:f8b0:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 576E51BCBF for ; Mon, 9 Jan 2023 12:10:34 -0800 (PST) Received: by mail-pf1-x42a.google.com with SMTP id 20so1641815pfu.13 for ; Mon, 09 Jan 2023 12:10:34 -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=U+Ecs18R9CtKFlvsB/pRW1Pzr0GQIhnnzaODeB/IhEo=; b=J3Xn9t/TLONNwRdZI6be/UThG5nLjVCwIRKvkdmxFEhtiUA+o4z4BW8VH9RKYbhq70 AbsHHH0Zjpq2BRSKBZFqW766Q5NVqjkChCTduz1b2mTAQNchXv+Gion6THdwI8mmtWIv +bQqv24KzIDhGZks3SvI52FGaG2o3DHDcxfl0= 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=U+Ecs18R9CtKFlvsB/pRW1Pzr0GQIhnnzaODeB/IhEo=; b=Fks58X7PLLm4ehdmdVzpvt4yRStOzkAFcZAas4UBI0c+bN8oZmxNBBnHDyHPgYmX5R lTId3Y+q53QytE7E7aJntj8/tQzgAhg3+uz9Z1uSymTemtly8CFCVz6RzOxT5kDof693 7WxqlmlSn48Wx++F6pjac4vQEY/aIRTyfKG6qy8CNNm91oYpgcebB+aOoPI4e6CFp9y9 rmPGfcwfPodNrPJouQ9/GtgsjNwAHD3KY862YYglg7sJGGTDP4mAJxPzAmZoQyzFaycs yNcFAbzy7iDp4hQtFvPXcR3Q0kxtn0RCZsK9f/E1O1Lq++QxGQHSqJ+SuBo7q6DlOxpZ 5dbw== X-Gm-Message-State: AFqh2krjOHnthcLtV37SckaaNDPY5XlqTwfL72O29Xk79Ff5L59FqCbq QYrIDnrNc0yae44SF6lpZ5ko97WJ/IqXq7W+XIwHGz39550NUAE9DSHHIVYEUNYgSad0ayOixkF z9id1EsSR6vuuDaUD/E0fvH9ZTqqT6p1gj644KZCShCKMllnTy7IHqEmDkb9I6BxOsHSyR94LQV DTPEHHuxwcbKo= X-Google-Smtp-Source: AMrXdXsFvNZHTRAj5m5Qu9ebO47JRobxHIxZGgtsGNQiGeqRxSdNx/ohVQcPCotqGKZwYbGoDI87oA== X-Received: by 2002:a62:33c7:0:b0:583:2971:df8b with SMTP id z190-20020a6233c7000000b005832971df8bmr14911646pfz.20.1673295033113; Mon, 09 Jan 2023 12:10:33 -0800 (PST) Received: from bcacpedev-irv-3.lvn.broadcom.net ([192.19.161.250]) by smtp.gmail.com with ESMTPSA id 8-20020a621608000000b0058a3d8eab6asm265144pfw.134.2023.01.09.12.10.31 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 09 Jan 2023 12:10:32 -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: Mon, 9 Jan 2023 12:10:30 -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="00000000000017035c05f1da5c06" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --00000000000017035c05f1da5c06 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit On 01/09/2023 11:06 AM, Mark Brown wrote: > On Fri, Jan 06, 2023 at 07:35:59PM -0800, William Zhang wrote: >> On 01/06/2023 01:47 PM, Mark Brown wrote: >>> On Fri, Jan 06, 2023 at 12:07:59PM -0800, William Zhang wrote: > >>>> 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. > > You can put whatever logic is needed in the code - for something like > this an architecture based define isn't ideal but is probably good > enough if need be (though I'd not be surprised if it turned out that > there was also some performance benefit for the MIPS systems too, at > least for smaller transfers). > I just don't know what other logic I can put in the driver to select interrupt or polling mode. Only the end user know if performance or cpu usage is more important to their application. --00000000000017035c05f1da5c06 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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