imx6ull 524Mhz GPMI interface NAND speed

[dc1]

Hello all, 

i have a imx6ull 524Mhz cpu connected with the interface GPMI to a NAND MT29F32G08CBADBWP in EDO mode 5:

gpmi-nand 1806000.gpmi-nand: enable the asynchronous EDO mode 5

with ubifs (an old version ... 2017)

My gpmi device tree is set as:

&gpmi {

compatible = "fsl,imx6ull-gpmi-nand", "fsl, imx6ul-gpmi-nand";
#address-cells = <1>;
#size-cells = <1>;
reg = <0x01806000 0x2000>, <0x01808000 0x4000>;
reg-names = "gpmi-nand", "bch";
interrupts = <GIC_SPI 15 IRQ_TYPE_LEVEL_HIGH>;
interrupt-names = "bch";
clocks = <&clks IMX6UL_CLK_GPMI_IO>,
<&clks IMX6UL_CLK_GPMI_APB>,
<&clks IMX6UL_CLK_GPMI_BCH>,
<&clks IMX6UL_CLK_GPMI_BCH_APB>,
<&clks IMX6UL_CLK_PER_BCH>;
clock-names = "gpmi_io", "gpmi_apb", "gpmi_bch",
"gpmi_bch_apb", "per1_bch";
dmas = <&dma_apbh 0>;
dma-names = "rx-tx";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_gpmi_nand_1>;
status = "okay";
nand-on-flash-bbt;
};

my speed test show this result :

dd if=/dev/zero of=./largefile bs=1M count=1024

1073741824 bytes (1.1 GB, 1.0 GiB) copied, 47.6832 s, 22.5 MB/s

dd if=/dev/zero of=./largefile bs=1M count=1024 oflag=dsync

1073741824 bytes (1.1 GB, 1.0 GiB) copied, 50.2484 s, 21.4 MB/s

dd if=/dev/zero of=./largefile bs=100M count=10

1048576000 bytes (1.0 GB, 1000 MiB) copied, 42.4279 s, 24.7 MB/s

dd if=/dev/zero of=./largefile bs=100M count=10 oflag=dsync

1048576000 bytes (1.0 GB, 1000 MiB) copied, 50.4285 s, 20.8 MB/s

My question is if it is possible to increase the gpmi frequency clock to reach better speed performance and, in case, how to do that?

Can you help me?

Thanks

[igorpadykov]

Hi Daniele

>My question is if it is possible to increase the gpmi frequency clock..

I am afraid it is not possible and gpmi (nand) driver selects operating frequency

automatically, one can refer to driver source comments:

4.4) We only support the fastest asynchronous mode of ONFI nand.
 *       For some ONFI nand, the mode 4 is the fastest mode;
 *       while for some ONFI nand, the mode 5 is the fastest mode.
..
The async mode requires 40MHz for mode 4, 50MHz for mode 5.

gpmi-lib.c\gpmi-nand\nand\mtd\drivers - linux-imx - i.MX Linux kernel 

Best regards
igor
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