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 X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 616DEC432C0 for ; Tue, 26 Nov 2019 10:48:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 93EF120637 for ; Tue, 26 Nov 2019 10:48:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=fpond.eu header.i=@fpond.eu header.b="TkGBgN7G" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727771AbfKZKsb (ORCPT ); Tue, 26 Nov 2019 05:48:31 -0500 Received: from mo4-p00-ob.smtp.rzone.de ([85.215.255.22]:14499 "EHLO mo4-p00-ob.smtp.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727737AbfKZKsb (ORCPT ); Tue, 26 Nov 2019 05:48:31 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1574765309; s=strato-dkim-0002; d=fpond.eu; h=Subject:References:In-Reply-To:Message-ID:To:From:Date: X-RZG-CLASS-ID:X-RZG-AUTH:From:Subject:Sender; bh=I31bQPpn/vbAjn5TTUO2KRld/rGkuqy8VkI9ImPhBsU=; b=TkGBgN7GgqLYbT+U2Nl1Bw4kUt4vDPN320xhSEDZTdviFgPXhio9HZcRWbjtmKExYQ b55fmGFn1fUcFvN3j1MgBRNbVl6z/2YIh0E6l9WLbqwsl+YuixVW9ckoFttzSybvvWel Bk+F9CFgRiEhNi4VhkAiTlzFfBKB2wycBDn6Ozt24EWPn54037bDUNXMXf5pS5TgY855 uGnq37pAd6jpg/kulbIdvvs3feCAlhfD7REAVFXF9LqPeKNzjvKMyCfDZYobZOJ+lJbp oZg5chLNdKcKkHlfbgJU9MUUIDo5qN35k9jrmqRVDtwteFOdJm4LmvswWwqEq5xuGuqt 733w== X-RZG-AUTH: ":OWANVUa4dPFUgKR/3dpvnYP0Np73amq+g13rqGzmt2bYDnKIKaws6YXTsc4=" X-RZG-CLASS-ID: mo00 Received: from oxapp04-01.back.ox.d0m.de by smtp-ox.front (RZmta 45.0.2 AUTH) with ESMTPSA id k05717vAQAjP4O5 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (curve X9_62_prime256v1 with 256 ECDH bits, eq. 3072 bits RSA)) (Client did not present a certificate); Tue, 26 Nov 2019 11:45:25 +0100 (CET) Date: Tue, 26 Nov 2019 11:45:25 +0100 (CET) From: Ulrich Hecht To: Yoshihiro Shimoda , linux-renesas-soc@vger.kernel.org Message-ID: <1619526348.1354132.1574765125512@webmail.strato.com> In-Reply-To: <1574403231-18512-1-git-send-email-yoshihiro.shimoda.uh@renesas.com> References: <1574403231-18512-1-git-send-email-yoshihiro.shimoda.uh@renesas.com> Subject: Re: [PATCH RFC 0/4] mmc: host: renesas_sdhi_sys_dmac: change dma_buswidth MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Priority: 3 Importance: Normal X-Mailer: Open-Xchange Mailer v7.10.1-Rev22 X-Originating-IP: 112.198.74.215 X-Originating-Client: open-xchange-appsuite Sender: linux-renesas-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org > On November 22, 2019 at 7:13 AM Yoshihiro Shimoda wrote: > > > This patch can improve performance when a sd card transfer size > is multiples of 32 like a sd memory card. However, this may > disimprove performance when a sd card transfer size is not > multiples of 32 because this patch uses PIO instead of SYS-DMAC. I have logged the DMA transfer sizes of a Marvell SD8897 WiFi/BT chip, and there transfers that are not multiples of 32 are infrequent (every second or so) and small (184 bytes); all large transfers are multiples of 32. Would it be practical to switch the DMA bus width down if odd sizes are encountered, and back up again otherwise? CU Uli