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=-4.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 3D50BC04AA7 for ; Mon, 13 May 2019 17:47:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 15DFD20879 for ; Mon, 13 May 2019 17:47:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=baylibre-com.20150623.gappssmtp.com header.i=@baylibre-com.20150623.gappssmtp.com header.b="aG5v8TAA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730987AbfEMRrt (ORCPT ); Mon, 13 May 2019 13:47:49 -0400 Received: from mail-pl1-f194.google.com ([209.85.214.194]:34109 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730143AbfEMRrs (ORCPT ); Mon, 13 May 2019 13:47:48 -0400 Received: by mail-pl1-f194.google.com with SMTP id w7so6851520plz.1 for ; Mon, 13 May 2019 10:47:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=baylibre-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:in-reply-to:references:date:message-id :mime-version; bh=7ftcbU8JnQmvm8sGh32+gWVqyGisGkp05zvI/Os1BUA=; b=aG5v8TAA+1qIp67dGGOJ7ud6fKmC9NYGNER2ymFATsKxSw7VEJIAcZr2RhZ15fOE+B xM9aXfO+Ft7I1MfUm4KhUZu+IaQTsAEf0ZUgfzyXoJqmDOKfJe66+f8zw4AuubJ+or27 ufNo6pYKwNT8Q2CQZo2VhJrv8HJ0BChKp1IwSD51GT5N3nyfqhziSRmyrdLi7fiCHqsO j3XOAMVG4Yp4wboAfnQSKvQq9UFhKNB3o2DaThW4zr3zp8xLy/YYiycKAQjGpm/IhWaZ ofn9Dn3m2QyeTutPItizv/1Me+LzhsVv7veUC9Qx4hrZZ1nCfKt/wt9RPLbvy6vlzNwK N55Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=7ftcbU8JnQmvm8sGh32+gWVqyGisGkp05zvI/Os1BUA=; b=RQz2BlUCJcNzfdz7OYmNzJ17IGsgRlWnVIUTS547wf9rAQiWw22dGaoHD/8IdKH3sb kaaJuHnFEfrHmB4zajQfR1plE0n7wKbhSuCDRZV6hipaAsvdTVuj8XWTkq3aIaFB8seT i+Z8QnksMBwCjj05JvMvAPu2rcqtIx6wECBIrP/Vwt0M9Cmg/mghSGG0IqaDpUzuSs/i uu+UWpZvRsyhgL+RksQhHKm7Js5yCPQ74bs2m+1PUr/DGTuoNPdDPNz+TFtnm3Xxuc+j OaddjaR4um7k9+sUitsSrOIcdD5EYs9izeyelQAOny7k78UeUg/3AKpMRVihtyg6JQ2i sRMg== X-Gm-Message-State: APjAAAU4Sa8pfmpIM7qghvoppPQ+a0tgpmpMtJKS/SyQIIjZ3vCCJHYz hhTGkYdrWaMsuYg8Ijnt8KlQ4w== X-Google-Smtp-Source: APXvYqykzOc6H2gQfaH2tmKL5VMylfiYXvxqcBKK0+ieVzRpKiH1CsSkvAVqvM2zkJDtRZ1QN5T4tw== X-Received: by 2002:a17:902:e708:: with SMTP id co8mr32206427plb.141.1557769667349; Mon, 13 May 2019 10:47:47 -0700 (PDT) Received: from localhost ([2601:602:9200:a1a5:fd66:a9bc:7c2c:636a]) by smtp.googlemail.com with ESMTPSA id w12sm14856903pgp.51.2019.05.13.10.47.46 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 13 May 2019 10:47:46 -0700 (PDT) From: Kevin Hilman To: Neil Armstrong , ulf.hansson@linaro.org Cc: baylibre-upstreaming@groups.io, Neil Armstrong , linux-mmc@vger.kernel.org, linux-amlogic@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] mmc: meson-gx: add ddr-access-quirk In-Reply-To: <20190513091548.16674-3-narmstrong@baylibre.com> References: <20190513091548.16674-1-narmstrong@baylibre.com> <20190513091548.16674-3-narmstrong@baylibre.com> Date: Mon, 13 May 2019 10:47:45 -0700 Message-ID: <7hd0kmckla.fsf@baylibre.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Neil Armstrong writes: > On the Amlogic G12A SoC family, (only) the SDIO controller fails to access > the data from DDR, leading to a broken controller. > > But each MMC controller has 1,5KiB of SRAM after the registers, that can > be used as bounce buffer to avoid direct DDR access from the integrated > DMAs (this SRAM may be used by the boot ROM when DDR is not yet initialized). > > The quirk is to disable the chained descriptor for this controller, and > use this SRAM memory zone as buffer for the bounce buffer fallback mode. > > The performance hit hasn't been evaluated, but the fix has been tested > using a WiFi AP6398S SDIO module, and the iperf3 Bandwidth measurement gave > 55.2 Mbits/sec over a 63 Hours long test, with the SDIO ios set as High-Speed > at 50MHz clock. It gave 170 Mbits/sec as SDR104 and 200MHz clock. > > Signed-off-by: Neil Armstrong Reviewed-by: Kevin Hilman