Re: [RFC PATCH] drivers: ata: ahci_sunxi: Increased SATA/AHCI DMA TX/RX FIFOs

[Maxime Ripard]

Hi,

On Fri, May 10, 2019 at 09:25:50PM +0200, Uenal Mutlu wrote:
> Increasing the SATA/AHCI DMA TX/RX FIFOs (P0DMACR.TXTS and .RXTS) from
> default 0x0 each to 0x3 each gives a write performance boost of 120MB/s
> from lame 36MB/s to 45MB/s previously. Read performance is about 200MB/s
> [tested on SSD using dd bs=4K count=512K].
>
> Tested on the Banana Pi R1 (aka Lamobo R1) and Banana Pi M1 SBCs
> with Allwinner A20 32bit-SoCs (ARMv7-a / arm-linux-gnueabihf).
> These devices are RaspberryPi-like small devices.
>
> RFC: Since more than about 25 similar SBC/SoC models do use the
> ahci_sunxi driver, users are encouraged to test it on all the
> affected boards and give feedback.
>
> List 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/Category:Devices_with_SATA_port
>
> Signed-off-by: Uenal Mutlu <um@xxxxxxxxxxx>
> ---
>  drivers/ata/ahci_sunxi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/ata/ahci_sunxi.c b/drivers/ata/ahci_sunxi.c
> index 911710643305..257986431c79 100644
> --- a/drivers/ata/ahci_sunxi.c
> +++ b/drivers/ata/ahci_sunxi.c
> @@ -158,7 +158,7 @@ static void ahci_sunxi_start_engine(struct ata_port *ap)
>  	struct ahci_host_priv *hpriv = ap->host->private_data;
>
>  	/* Setup DMA before DMA start */
> -	sunxi_clrsetbits(hpriv->mmio + AHCI_P0DMACR, 0x0000ff00, 0x00004400);
> +	sunxi_clrsetbits(hpriv->mmio + AHCI_P0DMACR, 0x0000ffff, 0x00004433);

Having comments / defines here would be great, once fixed:
Acked-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxx>

Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com