Linux-ide Archive on lore.kernel.org
 help / color / Atom feed
* [PATCH v3] drivers: ata: ahci_sunxi: Increased SATA/AHCI DMA TX/RX FIFOs
@ 2019-05-13 14:24 Uenal Mutlu
  2019-07-05  8:48 ` [linux-sunxi] " Chen-Yu Tsai
  2019-07-05 16:17 ` Jens Axboe
  0 siblings, 2 replies; 3+ messages in thread
From: Uenal Mutlu @ 2019-05-13 14:24 UTC (permalink / raw)
  To: Jens Axboe, Maxime Ripard, Chen-Yu Tsai,
	linux-ide-u79uwXL29TY76Z2rM5mHXA,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA
  Cc: Uenal Mutlu, linux-sunxi-/JYPxA39Uh5TLH3MbocFFw,
	linux-amarula-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/,
	Jagan Teki, Pablo Greco, Mark Rutland, Oliver Schinagl,
	Linus Walleij, Hans de Goede, FUKAUMI Naoki, Andre Przywara,
	Stefan Monnier

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 <maxime.ripard-LDxbnhwyfcJBDgjK7y7TUQ@public.gmane.org>
Reviewed-by: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Uenal Mutlu <um-lNbj7F0cCK5BDgjK7y7TUQ@public.gmane.org>
---

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);
-- 
2.11.0

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [linux-sunxi] [PATCH v3] drivers: ata: ahci_sunxi: Increased SATA/AHCI DMA TX/RX FIFOs
  2019-05-13 14:24 [PATCH v3] drivers: ata: ahci_sunxi: Increased SATA/AHCI DMA TX/RX FIFOs Uenal Mutlu
@ 2019-07-05  8:48 ` " Chen-Yu Tsai
  2019-07-05 16:17 ` Jens Axboe
  1 sibling, 0 replies; 3+ messages in thread
From: Chen-Yu Tsai @ 2019-07-05  8:48 UTC (permalink / raw)
  To: Jens Axboe, Hans de Goede
  Cc: Maxime Ripard, linux-ide, linux-arm-kernel, linux-kernel,
	Uenal Mutlu, linux-sunxi, linux-amarula, Jagan Teki, Pablo Greco,
	Mark Rutland, Oliver Schinagl, Linus Walleij, FUKAUMI Naoki,
	Andre Przywara, Stefan Monnier

On Mon, May 13, 2019 at 10:24 PM Uenal Mutlu <um@mutluit.com> wrote:
>
> 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 <maxime.ripard@bootlin.com>
> Reviewed-by: Hans de Goede <hdegoede@redhat.com>
> Signed-off-by: Uenal Mutlu <um@mutluit.com>

Tested-by: Chen-Yu Tsai <wens@csie.org>

on a Lamabo R1 as well.

Maybe we could merge this soon so it makes the next merge window?

Thanks.

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH v3] drivers: ata: ahci_sunxi: Increased SATA/AHCI DMA TX/RX FIFOs
  2019-05-13 14:24 [PATCH v3] drivers: ata: ahci_sunxi: Increased SATA/AHCI DMA TX/RX FIFOs Uenal Mutlu
  2019-07-05  8:48 ` [linux-sunxi] " Chen-Yu Tsai
@ 2019-07-05 16:17 ` Jens Axboe
  1 sibling, 0 replies; 3+ messages in thread
From: Jens Axboe @ 2019-07-05 16:17 UTC (permalink / raw)
  To: Uenal Mutlu, Maxime Ripard, Chen-Yu Tsai, linux-ide,
	linux-arm-kernel, linux-kernel
  Cc: linux-sunxi, linux-amarula, Jagan Teki, Pablo Greco,
	Mark Rutland, Oliver Schinagl, Linus Walleij, Hans de Goede,
	FUKAUMI Naoki, Andre Przywara, Stefan Monnier

On 5/13/19 8:24 AM, Uenal Mutlu wrote:
> 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

Applied for 5.3, thanks.

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, back to index

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-05-13 14:24 [PATCH v3] drivers: ata: ahci_sunxi: Increased SATA/AHCI DMA TX/RX FIFOs Uenal Mutlu
2019-07-05  8:48 ` [linux-sunxi] " Chen-Yu Tsai
2019-07-05 16:17 ` Jens Axboe

Linux-ide Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-ide/0 linux-ide/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-ide linux-ide/ https://lore.kernel.org/linux-ide \
		linux-ide@vger.kernel.org linux-ide@archiver.kernel.org
	public-inbox-index linux-ide


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-ide


AGPL code for this site: git clone https://public-inbox.org/ public-inbox