From patchwork Mon May 13 14:24:10 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Uenal Mutlu X-Patchwork-Id: 10941009 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 64DB1933 for ; Mon, 13 May 2019 14:25:04 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 53A7E28173 for ; Mon, 13 May 2019 14:25:04 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 44C8E2817F; Mon, 13 May 2019 14:25:04 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,TVD_RCVD_SPACE_BRACKET autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 1965627B13 for ; Mon, 13 May 2019 14:25:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To: References:List-Owner; bh=VkMtdWYKvqBKk3e5nsb2oSCQ7/i6ILGNJ9G30WzfwwM=; b=dhR lLF1HS0z1Iw8ATlWJrNkYsB5lzCXeRq6NWJoiKGDnyFP0DzEsmK8hk/hM5gfqKJVzfbS20UAKtrWR KFChW9BQjSSUmMlejAZlogUQCUraRP0z9dmMb2vrsMxdFfoUTB+Kpcabq0VPGrjaNwIU72gjW9tG7 M69LjSV96H16B4wLhIQYo/CgMH1OHxHf4o4xaqVBr9UpqOcFNzwGKuaIISjuIriyhfWAbrrPMoRpL sg+5X4JcQE17YkDdpau1e8zp6RQpsDbiai9Qv/vnFqJTXU8xo9ERq/qCyehQ1+EH+JWRWZ4ArzP5v brG6fmI4tEB1dTuBRGj+WXa3B/Ccm2A==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hQBsu-0006y7-6y; Mon, 13 May 2019 14:24:56 +0000 Received: from mutluit.com ([82.211.8.197]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hQBsm-0006sz-Hf for linux-arm-kernel@lists.infradead.org; Mon, 13 May 2019 14:24:51 +0000 Received: from c22-local.mutluit.com (ip4d155212.dynamic.kabel-deutschland.de [77.21.82.18]:58476) by mutluit.com (s2.mutluit.com [82.211.8.197]:25) with ESMTP ([XMail 1.27 ESMTP Server]) id for from ; Mon, 13 May 2019 10:24:41 -0400 From: Uenal Mutlu To: Jens Axboe , Maxime Ripard , Chen-Yu Tsai , linux-ide@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v3] drivers: ata: ahci_sunxi: Increased SATA/AHCI DMA TX/RX FIFOs Date: Mon, 13 May 2019 16:24:10 +0200 Message-Id: <20190513142410.9299-1-um@mutluit.com> X-Mailer: git-send-email 2.11.0 X-Patchwork-Bot: notify X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190513_072449_032044_164B56F7 X-CRM114-Status: GOOD ( 12.14 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Uenal Mutlu , Oliver Schinagl , Andre Przywara , Linus Walleij , Pablo Greco , FUKAUMI Naoki , Hans de Goede , linux-sunxi@googlegroups.com, Jagan Teki , linux-amarula@amarulasolutions.com, Stefan Monnier MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Increasing the SATA/AHCI DMA TX/RX FIFOs (P0DMACR.TXTS and .RXTS, ie. TX_TRANSACTION_SIZE and RX_TRANSACTION_SIZE) from default 0x0 each to 0x3 each, gives a write performance boost of 120 MiB/s to 132 MiB/s from lame 36 MiB/s to 45 MiB/s previously. Read performance is above 200 MiB/s. [tested on SSD using dd bs=4K/8K/12K/16K/20K/24K/32K: peak-perf at 12K] Tested on the SBCs Banana Pi R1 (aka Lamobo R1) and Banana Pi M1 which are based on the Allwinner A20 32bit-SoC (ARMv7-a / arm-linux-gnueabihf). These devices are RaspberryPi-like small devices. This problem of slow SATA write-speed with these small devices lasts for about 7 years now (beginning with the A10 SoC). Many commentators throughout the years wrongly assumed the slow write speed was a hardware limitation. This patch finally solves the problem, which in fact was just a hard-to-find software problem due to lack of SATA/AHCI documentation by the SoC-maker Allwinner Technology. Lists of the affected sunxi and other boards and SoCs with SATA using the ahci_sunxi driver: $ grep -i -e "^&ahci" arch/arm/boot/dts/sun*dts and http://linux-sunxi.org/SATA#Devices_with_SATA_ports See also http://linux-sunxi.org/Category:Devices_with_SATA_port Acked-by: Maxime Ripard Reviewed-by: Hans de Goede Signed-off-by: Uenal Mutlu --- v3: * Removed RFC from Subject line, and also the explicit call for RFC in the text, thereby submitting the patch for official merging. v2: * Commented the patch in-place in ahci_sunxi.c * With bs=12K and no conv=... passed to dd, the write performance rises further to 132 MiB/s * Changed MB/s to MiB/s * Posted the story behind the patch: http://lkml.iu.edu/hypermail/linux/kernel/1905.1/03506.html * Posted a dd test script to find optimal bs, and some results: https://bit.ly/2YoOzEM v1: * States bs=4K for dd and a write performance of 120 MiB/s --- drivers/ata/ahci_sunxi.c | 47 +++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 45 insertions(+), 2 deletions(-) diff --git a/drivers/ata/ahci_sunxi.c b/drivers/ata/ahci_sunxi.c index 911710643305..018186a39a69 100644 --- a/drivers/ata/ahci_sunxi.c +++ b/drivers/ata/ahci_sunxi.c @@ -157,8 +157,51 @@ static void ahci_sunxi_start_engine(struct ata_port *ap) void __iomem *port_mmio = ahci_port_base(ap); struct ahci_host_priv *hpriv = ap->host->private_data; - /* Setup DMA before DMA start */ - sunxi_clrsetbits(hpriv->mmio + AHCI_P0DMACR, 0x0000ff00, 0x00004400); + /* Setup DMA before DMA start + * + * NOTE: A similar SoC with SATA/AHCI by Texas Instruments documents + * this Vendor Specific Port (P0DMACR, aka PxDMACR) in its + * User's Guide document (TMS320C674x/OMAP-L1x Processor + * Serial ATA (SATA) Controller, Literature Number: SPRUGJ8C, + * March 2011, Chapter 4.33 Port DMA Control Register (P0DMACR), + * p.68, https://www.ti.com/lit/ug/sprugj8c/sprugj8c.pdf) + * as equivalent to the following struct: + * + * struct AHCI_P0DMACR_t + * { + * unsigned TXTS : 4; + * unsigned RXTS : 4; + * unsigned TXABL : 4; + * unsigned RXABL : 4; + * unsigned Reserved : 16; + * }; + * + * TXTS: Transmit Transaction Size (TX_TRANSACTION_SIZE). + * This field defines the DMA transaction size in DWORDs for + * transmit (system bus read, device write) operation. [...] + * + * RXTS: Receive Transaction Size (RX_TRANSACTION_SIZE). + * This field defines the Port DMA transaction size in DWORDs + * for receive (system bus write, device read) operation. [...] + * + * TXABL: Transmit Burst Limit. + * This field allows software to limit the VBUSP master read + * burst size. [...] + * + * RXABL: Receive Burst Limit. + * Allows software to limit the VBUSP master write burst + * size. [...] + * + * Reserved: Reserved. + * + * + * NOTE: According to the above document, the following alternative + * to the code below could perhaps be a better option + * (or preparation) for possible further improvements later: + * sunxi_clrsetbits(hpriv->mmio + AHCI_P0DMACR, 0x0000ffff, + * 0x00000033); + */ + sunxi_clrsetbits(hpriv->mmio + AHCI_P0DMACR, 0x0000ffff, 0x00004433); /* Start DMA */ sunxi_setbits(port_mmio + PORT_CMD, PORT_CMD_START);