Re: [PATCH v3] drivers: ata: ahci_sunxi: Increased SATA/AHCI DMA TX/RX FIFOs

[Jens Axboe]

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