sunxi: backport increased SATA/AHCI DMA TX/RX FIFOs
This backports SATA performance boost from 5.3 kernel: 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] dd bs Before MB/s After MB/s Increase 4k 14.4 16.5 15% 64k 34.5 74.4 116% 1M 40.5 93.2 130% Ref: https://forum.openwrt.org/t/sunxi-sata-write-speed-patch/54555/5 Signed-off-by: Aleksander Jan Bajkowski <A.Bajkowski@stud.elka.pw.edu.pl> [commit subject & description tweaks] Signed-off-by: Petr Štetiar <ynezz@true.cz>master
Aleksander Jan Bajkowski
4 years ago
committed by
Petr Štetiar
parent
fbd00bb8d4
commit
5499b24dc0
@ -0,0 +1,94 @@
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From 120357ea176e420d313cf8cf2ff35fbe233d3bab Mon Sep 17 00:00:00 2001
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From: Uenal Mutlu <um@mutluit.com>
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Date: Mon, 13 May 2019 16:24:10 +0200
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Subject: [PATCH] drivers: ata: ahci_sunxi: Increased SATA/AHCI DMA TX/RX FIFOs
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Increasing the SATA/AHCI DMA TX/RX FIFOs (P0DMACR.TXTS and .RXTS, ie.
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TX_TRANSACTION_SIZE and RX_TRANSACTION_SIZE) from default 0x0 each
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to 0x3 each, gives a write performance boost of 120 MiB/s to 132 MiB/s
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from lame 36 MiB/s to 45 MiB/s previously.
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Read performance is above 200 MiB/s.
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[tested on SSD using dd bs=4K/8K/12K/16K/20K/24K/32K: peak-perf at 12K]
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Tested on the SBCs Banana Pi R1 (aka Lamobo R1) and Banana Pi M1 which
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are based on the Allwinner A20 32bit-SoC (ARMv7-a / arm-linux-gnueabihf).
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These devices are RaspberryPi-like small devices.
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This problem of slow SATA write-speed with these small devices lasts
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for about 7 years now (beginning with the A10 SoC). Many commentators
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throughout the years wrongly assumed the slow write speed was a
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hardware limitation. This patch finally solves the problem, which
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in fact was just a hard-to-find software problem due to lack of
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SATA/AHCI documentation by the SoC-maker Allwinner Technology.
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Lists of the affected sunxi and other boards and SoCs with SATA using
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the ahci_sunxi driver:
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$ grep -i -e "^&ahci" arch/arm/boot/dts/sun*dts
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and http://linux-sunxi.org/SATA#Devices_with_SATA_ports
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See also http://linux-sunxi.org/Category:Devices_with_SATA_port
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Tested-by: Chen-Yu Tsai <wens@csie.org>
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Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
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Reviewed-by: Hans de Goede <hdegoede@redhat.com>
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Signed-off-by: Uenal Mutlu <um@mutluit.com>
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Signed-off-by: Jens Axboe <axboe@kernel.dk>
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---
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drivers/ata/ahci_sunxi.c | 47 ++++++++++++++++++++++++++++++++++++++--
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1 file changed, 45 insertions(+), 2 deletions(-)
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--- a/drivers/ata/ahci_sunxi.c
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+++ b/drivers/ata/ahci_sunxi.c
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@@ -157,8 +157,51 @@ static void ahci_sunxi_start_engine(stru
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void __iomem *port_mmio = ahci_port_base(ap);
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struct ahci_host_priv *hpriv = ap->host->private_data;
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- /* Setup DMA before DMA start */
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- sunxi_clrsetbits(hpriv->mmio + AHCI_P0DMACR, 0x0000ff00, 0x00004400);
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+ /* Setup DMA before DMA start
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+ *
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+ * NOTE: A similar SoC with SATA/AHCI by Texas Instruments documents
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+ * this Vendor Specific Port (P0DMACR, aka PxDMACR) in its
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+ * User's Guide document (TMS320C674x/OMAP-L1x Processor
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+ * Serial ATA (SATA) Controller, Literature Number: SPRUGJ8C,
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+ * March 2011, Chapter 4.33 Port DMA Control Register (P0DMACR),
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+ * p.68, https://www.ti.com/lit/ug/sprugj8c/sprugj8c.pdf)
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+ * as equivalent to the following struct:
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+ *
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+ * struct AHCI_P0DMACR_t
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+ * {
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+ * unsigned TXTS : 4;
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+ * unsigned RXTS : 4;
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+ * unsigned TXABL : 4;
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+ * unsigned RXABL : 4;
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+ * unsigned Reserved : 16;
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+ * };
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+ *
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+ * TXTS: Transmit Transaction Size (TX_TRANSACTION_SIZE).
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+ * This field defines the DMA transaction size in DWORDs for
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+ * transmit (system bus read, device write) operation. [...]
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+ *
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+ * RXTS: Receive Transaction Size (RX_TRANSACTION_SIZE).
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+ * This field defines the Port DMA transaction size in DWORDs
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+ * for receive (system bus write, device read) operation. [...]
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+ *
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+ * TXABL: Transmit Burst Limit.
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+ * This field allows software to limit the VBUSP master read
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+ * burst size. [...]
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+ *
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+ * RXABL: Receive Burst Limit.
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+ * Allows software to limit the VBUSP master write burst
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+ * size. [...]
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+ *
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+ * Reserved: Reserved.
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+ *
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+ *
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+ * NOTE: According to the above document, the following alternative
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+ * to the code below could perhaps be a better option
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+ * (or preparation) for possible further improvements later:
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+ * sunxi_clrsetbits(hpriv->mmio + AHCI_P0DMACR, 0x0000ffff,
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+ * 0x00000033);
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+ */
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+ sunxi_clrsetbits(hpriv->mmio + AHCI_P0DMACR, 0x0000ffff, 0x00004433);
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/* Start DMA */
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sunxi_setbits(port_mmio + PORT_CMD, PORT_CMD_START);
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