emmc speed too low in mx6ull

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emmc speed too low in mx6ull

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Contributor III

my imx6ull connects emmc(MICRON 4GB  MTFC4GACAJCN-4MIT
) to usdhc2.

with 8-bit data bus mode :

&usdhc2 {
pinctrl-names = "default", "state_100mhz", "state_200mhz";
pinctrl-0 = <&pinctrl_usdhc2_8bit>;
pinctrl-1 = <&pinctrl_usdhc2_8bit_100mhz>;
pinctrl-2 = <&pinctrl_usdhc2_8bit_200mhz>;
bus-width = <8>;

no-1-8-v;

non-removable;
status = "okay";
};

Write Test CMD: time dd if=/dev/zero of=./500MB bs=1M count=500

Read Test CMD: time dd of=/dev/null if=./500MB bs=1M count=500

Speed: read=20MB/s write=15MB/s    (work at MMC_TIMING_MMC_DDR52 )

root@Router:~# cat /sys/kernel/debug/mmc1/ios
clock: 52000000 Hz
vdd: 21 (3.3 ~ 3.4 V)
bus mode: 2 (push-pull)
chip select: 0 (don't care)
power mode: 2 (on)
bus width: 3 (8 bits)
timing spec: 8 (mmc DDR52)
signal voltage: 0 (3.30 V)
driver type: 0 (driver type B)

 

if with 4-bit data bus mode :

&usdhc2 {

pinctrl-names = "default";
pinctrl-0 = <&pinctrl_usdhc2>;
bus-width = <4>;

non-removable;
status = "okay";
};

Speed: read=29MB/s write=15MB/s    (work at MMC_TIMING_MMC_DDR52)

 

I do a test in a 3rd part demo board 100ask_imx6ll (MYIR tech), its speed is only read=30MB/s write=13MB/s.

Also if i replace my imx6ull emmc with SkyHigh's S40FC004C1B1I000 (4GB), the test speed is read=50MB/s write=11MB/s.(also only work at MMC_TIMING_MMC_DDR52 )

 

What is NXP's EVK board emmc speed test reslut?  anyone test for me?

Anyone know why 8-bit mode speed is lower then 4-bit mode?

How to reach a higher MMC HS200 mode ? (RM say imx6ull support HS200 mode)

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1 Solution
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NXP TechSupport
NXP TechSupport

Yes, For the imx6ull support HS200 mode, for the 8bit support, you need to make  imx6ull's emmc controler and emmc flash powered 1.8V, and in the code remove "no-1-8-v;".

For your setting I see you are using the 3.3V, so only 4bit works.

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6 Replies
139 Views
NXP TechSupport
NXP TechSupport

Yes, For the imx6ull support HS200 mode, for the 8bit support, you need to make  imx6ull's emmc controler and emmc flash powered 1.8V, and in the code remove "no-1-8-v;".

For your setting I see you are using the 3.3V, so only 4bit works.

View solution in original post

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Contributor III

Thank you for your professional response,@b45499 

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NXP TechSupport
NXP TechSupport

You are welcome, wish you have a nice day.

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NXP TechSupport
NXP TechSupport

Which version BSP are you using? I will confirm it for you.

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Contributor III

the emmc part of our schemetic as below:

 999.png

our imx6ull's emmc controler and emmc flash are powered 3.3v only, so i add "no-1-8-v;" into usdhc2 node of dts.

Is that right?

&usdhc2 {
pinctrl-names = "default", "state_100mhz", "state_200mhz";
pinctrl-0 = <&pinctrl_usdhc2_8bit>;
pinctrl-1 = <&pinctrl_usdhc2_8bit_100mhz>;
pinctrl-2 = <&pinctrl_usdhc2_8bit_200mhz>;
bus-width = <8>;

no-1-8-v;

non-removable;
status = "okay";
};

if remove "no-1-8-v;" from usdhc2 node of dtsm,  our imx6ull probe emmc flash fail.

 

and i find in  linux-imx-5.4.24/drivers/mmc/host/sdhci-esdhc-imx.c

static int
sdhci_esdhc_imx_probe_dt(struct platform_device *pdev,
struct sdhci_host *host,
struct pltfm_imx_data *imx_data)
{

...

if (of_find_property(np, "no-1-8-v", NULL))
      host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;

...

}

and i find in linux-imx-5.4.24/drivers/mmc/host/sdhci.c

if (host->quirks2 & SDHCI_QUIRK2_NO_1_8_V) {
host->caps1 &= ~(SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 |
SDHCI_SUPPORT_DDR50);
/*
* The SDHCI controller in a SoC might support HS200/HS400
* (indicated using mmc-hs200-1_8v/mmc-hs400-1_8v dt property),
* but if the board is modeled such that the IO lines are not
* connected to 1.8v then HS200/HS400 cannot be supported.
* Disable HS200/HS400 if the board does not have 1.8v connected
* to the IO lines. (Applicable for other modes in 1.8v)
*/
mmc->caps2 &= ~(MMC_CAP2_HSX00_1_8V | MMC_CAP2_HS400_ES);
mmc->caps &= ~(MMC_CAP_1_8V_DDR | MMC_CAP_UHS);
}

those two infos make we confuse?

how to let our imx6's emmc reach a higher speed?

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166 Views
Contributor III

we use the kernel pulled from NXP's https://source.codeaurora.org/external/imx/linux-imx branch imx_5.4.24_2.1.0 recently.

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