DESK-MX6UL-L/Peripherals/USB Host

History
Version	Issue Date	Notes
1.0.0	Jul 2021	First DESK release

Peripheral USB Host

The USB Host port requires to configure the USB VBUS regulator and the gpio used for enabling the 5V USB power switch.

Device tree configuration

Here below an example of device tree configuration used on standard DAVE's kit for the AXEL ULite SOM:

From imx6ul-axelulite-cb003a.dts:

        reg_usb_otg1_vbus: regulator@2 {
                compatible = "regulator-fixed";
                reg = <2>;
                pinctrl-names = "default";
                pinctrl-0 = <&pinctrl_usb_otg1>;
                regulator-name = "usb_otg1_vbus";
                regulator-min-microvolt = <5000000>;
                regulator-max-microvolt = <5000000>;
                gpio = <&gpio1 18 GPIO_ACTIVE_HIGH>;
                enable-active-high;
        };
...
...
&usbotg1 {
        vbus-supply = <&reg_usb_otg1_vbus>;
        disable-over-current;
        dr_mode = "host";
        status = "okay";
};
...
...
&iomuxc {
        pinctrl-0 = <&pinctrl_hog_gpios>;
        imx6ul-axelulite {
...
...
                pinctrl_usb_otg1: usbotg1grp {
                        fsl,pins = <
                                MX6UL_PAD_UART1_CTS_B__GPIO1_IO18       0x10b0          /* HOST PWR */
                                MX6UL_PAD_GPIO1_IO03__GPIO1_IO03        0x10b0          /* HOST OC */
                        >;
                };
};

Accessing the peripheral

Linux messages at boot time

When a USB peripheral is inserted, in the following example a memory mass storage device, the kernel recognizes the device (i.e. xlass, vendor id, product id, etc.)

root@desk-mx6ul-axelulite:~# [  564.193377] usb 1-1: new high-speed USB device number 2 using ci_hdrc
[  564.435616] usb 1-1: New USB device found, idVendor=0951, idProduct=1665
[  564.442457] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  564.457846] usb 1-1: Product: DataTraveler 2.0
[  564.462455] usb 1-1: Manufacturer: Kingston
[  564.474290] usb 1-1: SerialNumber: 50E549C202681071F97202CB
[  564.488603] usb-storage 1-1:1.0: USB Mass Storage device detected
[  564.508986] scsi host0: usb-storage 1-1:1.0
[  565.526470] scsi 0:0:0:0: Direct-Access     Kingston DataTraveler 2.0 0000 PQ: 0 ANSI: 4
[  565.555313] sd 0:0:0:0: [sda] 15151168 512-byte logical blocks: (7.76 GB/7.22 GiB)
[  565.583739] sd 0:0:0:0: [sda] Write Protect is off
[  565.599208] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[  565.637032]  sda: sda1
[  565.663492] sd 0:0:0:0: [sda] Attached SCSI removable disk

Additional information

If the root file system configuration does not automatically mount the partition, it is possible to mount the device using the following command:

root@desk-mx6ul-axelulite:~# mkdir -p /mnt/usb
root@desk-mx6ul-axelulite:~# mount /dev/sda1 /mnt/usb
[  640.717947] FAT-fs (sda1): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.
root@desk-mx6ul-axelulite:~#  ls -la /mnt/usb
total 6756
drwxr-xr-x 3 root root   16384 Jan  1  1970 .
drwxr-xr-x 4 root root    4096 Oct  7 16:33 ..
drwxr-xr-x 2 root root   16384 Feb 26  2020 System Volume Information
-rwxr-xr-x 1 root root 6881192 Mar 31  2020 uImage-4.14.98-xelk-5.0.0-rc2+gb0960b6
root@desk-mx6ul-axelulite:~#

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