Slow SD Card

Honestly, It has been 2 months since this topic begins, and I also dealt with other cases during this period. Sorry to say I really don’t know what is gpio12 and gpio8 doing here. Share the board schematic and dts will be more clear to me.

Also, what is the exact dmesg that has sdcard detected but slow speed? Is it from 6/9? Or something else?

Hi Wayne,

Here are the schematic for SD card and connection to Nano SOM socket. GPIO12 is used for card detection pin and it connects to ground.
Nano SOM Socket Schematic.pdf (130.2 KB)
SD Card Schematic.pdf (78.4 KB)

Here is the dts fiile from tegra210-p3448-0002-p3449-0000-b00.dtb
org.dts (332.2 KB)

Here is the dmesg after deleted max-clk-limit.
dmesg sd card detect after removed max_clk_limit.txt (72.1 KB)


Then the problem is you don’t have cd-gpio. Your design does not match our design guide.

Doesn’t your sdcard slot need hotplug function?

No, it on a custom carrier board under a Nano SOM.

Sorry, no hot plug function!!!

Then please add “non-removable” to your sdhci controller, if there is no cd-gpios.

HI Wayne,
I have added non-removable, and built DT, see attached. The SD card still slow. Please help.
tegra210-soc-shield.dtsi (6.6 KB)

If you change anything, attach both new dts and dmesg. Thanks.

tegra210-soc-shield.dtsi this dtsi is not in use by jetson nano… Do you really know what file to modify?

Opps!! sorry for the wrong file., here is the correct one.
tegra210-sdhci.dtsi (5.7 KB)

Could it be that my circuit uses level shifter from 1.8v to 3.3V? Should I disable 3.3V in dts file?

And where is the dmesg…

Please also add those back…

nvidia,min-tap-delay = <106>;
nvidia,max-tap-delay = <185>;

And where is your vmmc-supply ? It is needed for the sdmmc_vdd_en.

Do I added vmmc-supply = <0x4c>; to the sdhci file even I saw vmmc and vqmmc in the tegra210-p3448-0002-p3449-0000-b00.dts file? Do I need vqmmc to sdhci file too?

Just share me you current full dts and your dmesg. You can not just tell me something like 0x4c and ask me if this would work or not. This hex value represents some regulator in the dts, this value is only valuable in your dts. It does not work on other users’ dts files. Thus, you tell me 0x4c and my answer is simple, I don’t know what is it.

Any problem to reveal those files?

Hi Wayne,

Here are the dts and dmesg files.
org.dts (332.3 KB)
dmesg_with_rebuilt_DT.txt (99.5 KB)


Is your SDMMC_VDD_EN connecting to a always-on 3.3v power source?

Hi Wayne,

I do not use SDMMC_VDD_EN. per attached schematic, I uses level shifter, 1.8V connect to Nano and 3.3V to SD card. the chip enable is always enable and is connected to 1.8V.

SD Card Schematic.pdf (78.4 KB)