DESK-MX9-L/Peripherals/USB1 OTG
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Contents
Peripheral USB1 OTG[edit | edit source]
AURA SOM supports OTG/Host/Peripheral modes: on AURA Evaluation Kit the USB1 OTG port is configured as peripheral.
Device tree configuration[edit | edit source]
Here below is an example of device tree configuration used on standard DAVE's kit for the AURA SOM:
From kernel device tree imx93-aura.dtsi:
...
&usbotg1 {
dr_mode = "peripheral";
hnp-disable;
srp-disable;
adp-disable;
disable-over-current;
samsung,picophy-pre-emp-curr-control = <3>;
samsung,picophy-dc-vol-level-adjust = <7>;
status = "disabled";
};
...
From kernel device tree imx93-aura-cb2001.dts:
/ {
...
&usbotg1 {
dr_mode = "peripheral";
status = "okay";
};
...
Accessing the peripheral[edit | edit source]
Usage with mass-storage[edit | edit source]
root@desk-mx93:~# dd if=/dev/zero of=mass_storage count=256 bs=1M 256+0 records in 256+0 records out 268435456 bytes (268 MB, 256 MiB) copied, 0.774426 s, 347 MB/s root@desk-mx93:~# mkfs.msdos mass_storage mkfs.fat 4.2 (2021-01-31) root@desk-mx93:~# mkdir loop root@desk-mx93:~# mount -o loop mass_storage loop [ 2309.051910] loop0: detected capacity change from 0 to 524288 root@desk-mx93:~# echo "Test USB OTG with mass storage device" > loop/usb.txt root@desk-mx93:~# umount loop root@desk-mx93:~#
then insert the g_mass_storage kernel module driver enabling an Windows PC to see it as a removable device
root@desk-mx93:~# modprobe g_mass_storage removable=y file=mass_storage [ 2366.224448] Mass Storage Function, version: 2009/09/11 [ 2366.229698] LUN: removable file: (no medium) [ 2366.234576] LUN: removable file: /home/root/mass_storage [ 2366.239928] Number of LUNs=1 [ 2366.242990] g_mass_storage gadget.0: Mass Storage Gadget, version: 2009/09/11 [ 2366.250151] g_mass_storage gadget.0: userspace failed to provide iSerialNumber [ 2366.257373] g_mass_storage gadget.0: g_mass_storage ready root@desk-mx93:~#
Once the USB cable is connected to the PC, the kernel prints the following messages:
[32262.935133] usb 1-1: new high-speed USB device number 2 using ehci-pci [32263.305571] usb 1-1: New USB device found, idVendor=0525, idProduct=a4a5, bcdDevice= 6.01 [32263.305574] usb 1-1: New USB device strings: Mfr=3, Product=4, SerialNumber=0 [32263.305575] usb 1-1: Product: Mass Storage Gadget [32263.305577] usb 1-1: Manufacturer: Linux 6.1.55-desk-mx9-l-5.0.0+g8942d3259e9b with 4c100000.usb [32263.337697] usb-storage 1-1:1.0: USB Mass Storage device detected [32263.337819] usb-storage 1-1:1.0: Quirks match for vid 0525 pid a4a5: 10000 [32263.337867] scsi host4: usb-storage 1-1:1.0 [32263.337968] usbcore: registered new interface driver usb-storage [32263.340492] usbcore: registered new interface driver uas [32264.367940] scsi 4:0:0:0: Direct-Access Linux File-Stor Gadget 0601 PQ: 0 ANSI: 2 [32264.368435] sd 4:0:0:0: Attached scsi generic sg2 type 0 [32264.385398] sd 4:0:0:0: Power-on or device reset occurred [32264.404893] sd 4:0:0:0: [sdb] 524288 512-byte logical blocks: (268 MB/256 MiB) [32264.519991] sd 4:0:0:0: [sdb] Write Protect is off [32264.519993] sd 4:0:0:0: [sdb] Mode Sense: 0f 00 00 00 [32264.637756] sd 4:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [32264.942269] sdb: [32265.225654] sd 4:0:0:0: [sdb] Attached SCSI removable disk
