Teensy41 support SDHC - Storage init Error

[EmbedWise]

Describe the bug
Working on the Teensy41 and trying to get the SD Card functionality to work. For this using the application developed by @bdkrae / @ufechner7. See https://github.com/bdkrae/zephyr_teensy4_test. Which is based on the zephyr/samples/subsys/fs/fat_fs.

Please also mention any information which could help others to understand
the problem you're facing:

• Using a Teensy41
• SanDisk Edge 4GB Micro SD, both tried with a formatted (MS-DOS and ExFAT partition)

I have also tried to follow the instructions

Card voltage switch
Teensy 4.1 has no hardware to switch card voltage. As a workaround in the file zephyr/drivers/disk/usdhc.c the line 502 needs to be changed:

#define SDMMCHOST_NOT_SUPPORT USDHC_HOST_CTRL_CAP_VS18(1)

This prevents the driver from trying to switch over to 1,8V supply for the card. Also, a dummy pin is defined in board defs.

I cannot find this Macro where that is defined. I already tried using the FLAG directly USDHC_HOST_CTRL_CAP_VS18_MASK. Still the same error.

To Reproduce
Using Zephyr 2.7.1

Expected behavior
SD Card should have been mounted

Logs and console output

[00:00:00.501,000] <inf> usdhc: USDHC detection other than GPIO
[00:00:00.501,000] <err> sdhc: Storage init ERROR!

Environment:

• OS: MacOS
• Toolchain GNU 10.3.1
• Zephyr 2.7.1

[EmbedWise]

I tested the interface with Arduino and the same SD card. Which works and shows both information and files on the SD card. So this confirms it is setting/driver related

[EmbedWise]

When the function usdhc_board_access_init is ran in zephyr/driver/disk/usdhc.c

if (!priv->detect_gpio) {
		LOG_INF("USDHC detection other than GPIO");
		priv->inserted = true;
		/* DATA3 does not monitor card insertion */
		base->PROT_CTRL &= ~USDHC_PROT_CTRL_D3CD_MASK;
		if ((base->PRES_STATE & USDHC_PRES_STATE_CINST_MASK) != 0) {
			priv->inserted = true;
		} else {
			priv->inserted = false;
			return -ENODEV;
		}
	} else {
		ret = usdhc_cd_gpio_init(priv->detect_gpio,
				config->detect_pin,
				config->detect_flags,
				&priv->detect_cb);
		if (ret) {
			return ret;
		}
		ret = gpio_pin_get(priv->detect_gpio, config->detect_pin);
		if (ret < 0) {
			return ret;
		}

		gpio_level = ret;

		if (gpio_level == 0) {
			priv->inserted = false;
			LOG_ERR("NO SD inserted!");

			return -ENODEV;
		}

		priv->inserted = true;
		LOG_INF("SD inserted!");
	}

Additional information:
The card present switch is not connected to the i.mxrt of the Teensy 4.1 .

So the cd-gpios in the dts should not be there.

The statement if ((base->PRES_STATE & USDHC_PRES_STATE_CINST_MASK) != 0) { evaluates false and therefore does not detect the SD card. I could not find where this flag should be set.

Result is the card is never detected

A dirty workaround is to add this to the dts or overlay and then it works:

&usdhc1 {
	status = "okay";
	no-1-8-v;
	cd-gpios = < &gpio3 21 GPIO_ACTIVE_HIGH>;
};

Note that I also add no-1-8-v;
Which applicable to the Teensy4.1

[jfischer-no]

@EmbedWise , would you like to open a PR to fix it in boards/arm/teensy4/teensy41.dts please?

[danieldegrasse]

@EmbedWise I don't have a teensy board to test this fix on, but looking at the schematic for the board it looks like the chip detect line for the SD card is not routed. The USDHC driver supports detecting a card via the internal pull up resistor on the DAT3 line. I've opened a PR (#42379) to switch the teensy41 board to using the DAT3 method of detecting SD card presence, instead of the dummy GPIO that was in use. Can you test that PR and verify it works for you? I would use the tests/drivers/disk test.