DESK-MX6-L/Pheripherals/USB Host

History
Version	Issue Date	Notes
1.0.0	Oct 2020	First DESK release

Contents

Peripheral USB HostEdit

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

Device tree configurationEdit

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

From imx6qdl-axelcommon.dtsi:

    regulators {
        compatible = "simple-bus";
 
        reg_usb_h1_vbus: usb_h1_vbus {
            compatible = "regulator-fixed";
            regulator-name = "usb_h1_vbus";
            regulator-min-microvolt = <5000000>;
            regulator-max-microvolt = <5000000>;
            gpio = <&gpio2 11 0>;
            enable-active-high;
        };
    };
...
...
&usbh1 {
    vbus-supply = <&reg_usb_h1_vbus>;
    status = "okay";
};

Accessing the peripheralEdit

Linux messages at boot timeEdit

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-mx6:~# [  635.250658] usb 1-1: new high-speed USB device number 3 using ci_hdrc
[  635.452905] usb 1-1: New USB device found, idVendor=18a5, idProduct=0302
[  635.459662] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  635.468681] usb 1-1: Product: STORE N GO
[  635.473596] usb 1-1: Manufacturer: Verbatim
[  635.477809] usb 1-1: SerialNumber: CCYYMMDDHHmmSSNUFLQ9
[  635.491337] usb-storage 1-1:1.0: USB Mass Storage device detected
[  635.497852] scsi host0: usb-storage 1-1:1.0
[  638.418581] scsi 0:0:0:0: Direct-Access     Verbatim STORE N GO       1100 PQ: 0 ANSI: 4
[  638.429992] sd 0:0:0:0: [sda] 61069312 512-byte logical blocks: (31.3 GB/29.1 GiB)
[  638.444695] sd 0:0:0:0: [sda] Write Protect is off
[  638.453430] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[  638.473696]  sda: sda1
[  638.481431] sd 0:0:0:0: [sda] Attached SCSI removable disk
root@desk-mx6:~#

Additional informationEdit

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-mx6:~# mkdir -p /mnt/usb
root@desk-mx6:~# mount /dev/sda1 /mnt/usb
[  831.081734] FAT-fs (sda1): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.
root@desk-mx6:~#  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-mx6:~#

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