Linux USB OTG: Difference between revisions

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<!-- Set release according to "release" parameter in URL and use RELEASE_SUMO_V1.0_DART-MX8M as default
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--> {{#lst:Yocto_Platform_Customization|{{#var:RELEASE_PARAM|RELEASE_SUMO_V1.0_DART-MX8M}}}} <!--
--> {{#lst:Yocto_Platform_Customization|{{#var:RELEASE_PARAM}}}} <!--
--> {{#lst:Android_Platform_Customization|{{#var:RELEASE_PARAM|RELEASE_N7.1.1_1.0.0_VAR-SOM-MX6}}}} <!--
--> {{#lst:B2QT_Platform_Customization|{{#var:RELEASE_PARAM}}}} <!--
--> {{#lst:Android_Platform_Customization|{{#var:RELEASE_PARAM}}}} <!--
--> {{#lst:Debian_Platform_Customization|{{#var:RELEASE_PARAM}}}} <!--
--> {{#vardefine:DEFAULT_DTS|{{#replace:{{#var:DEFAULT_DTB}}|.dtb|.dts}}}} <!--
--> {{#vardefine:DEFAULT_DTS_SOM|{{#replace:{{#var:DEFAULT_DTB_SOM}}|.dtb|.dts}}}} <!--
--> {{#vardefine:DTS_DIR|arch/{{#switch: {{#var:SOC_SERIES}}|imx8|imx9|am6=arm64|arm}}/boot/dts/{{#ifeq: {{#var:HARDWARE_NAME}}|
DART-MX8M|{{#ifeq: {{#var:YOCTO_NAME}}|Morty|variscite/|freescale/}}|{{#switch: {{#var:SOC_SERIES}} | imx8|imx9=freescale/|am6=ti/}}}}}} <!--  
--> {{PageHeader|{{#var:HARDWARE_NAME}} USB OTG}} {{DocImage|category1=Yocto|category2=Android}}[[Category:Debian]][[Category:DART-MX8M-MINI]][[Category:DART-MX8M]][[Category:DART-MX8M-PLUS]] __toc__
--> {{PageHeader|{{#var:HARDWARE_NAME}} USB OTG}} {{DocImage|category1=Yocto|category2=Android}}[[Category:Debian]][[Category:DART-MX8M-MINI]][[Category:DART-MX8M]][[Category:DART-MX8M-PLUS]] __toc__


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For example:<br>
For example:<br>
Follow either the "Build the Linux kernel from source code" or "Customizing the Linux kernel" Wiki pages and edit the following device tree file:<br>
Follow either the "Build the Linux kernel from source code" or "Customizing the Linux kernel" Wiki pages and edit the following device tree file:<br>
arch/arm64/boot/dts/{{#ifeq: {{#var:HARDWARE_NAME}}|DART-MX8M|{{#ifeq: {{#var:YOCTO_NAME}}|Morty|variscite/imx8m-var-dart-common.dtsi|freescale/fsl-imx8mq-var-dart-common.dtsi}}|freescale/fsl-imx8mm-var-dart.dts}} <br>
{{#switch: {{#var:HARDWARE_NAME}}
|DART-MX8M={{#ifeq: {{#var:YOCTO_NAME}}|Morty|{{#var:DTS_DIR}}imx8m-var-dart-common.dtsi|{{#var:DTS_DIR}}{{#var:DEFAULT_DTS_SOM | fsl-imx8mq-var-dart-common.dtsi }}}}
|DART-MX8M-MINI={{#var:DTS_DIR}}{{#var:DEFAULT_DTS|fsl-imx8mm-var-dart.dts }} for DART-MX8M-MINI, or {{#var:DTS_DIR}}{{#var:DEFAULT_DTS_SOM | fsl-imx8mm-var-som.dts }} for VAR-SOM-MX8M-MINI
|DART-MX8M-PLUS={{#var:DTS_DIR}}{{#var:DEFAULT_DTS|fsl-imx8mp-var-dart.dts }} for DART-MX8M-PLUS, or {{#var:DTS_DIR}}{{#var:DEFAULT_DTS_SOM | fsl-imx8mp-var-som.dts }} for VAR-SOM-MX8M-PLUS
|VAR-SOM-MX8M-NANO={{#var:DTS_DIR}}{{#if: {{#var:DEFAULT_DTS}} | {{#var:DEFAULT_DTS}}.dts | fsl-imx8mn-var-som.dts }}
|#default={{#var:DTS_DIR}}{{#var:DEFAULT_DTS}}
}} <br>


{{#ifeq: {{#var:HARDWARE_NAME}} | DART-MX8M |
{{#switch: {{#var:HARDWARE_NAME}}
|DART-MX8M=
<syntaxhighlight lang="diff">
<syntaxhighlight lang="diff">
&usb_dwc3_0 {
&usb_dwc3_0 {
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};
};
</syntaxhighlight>
</syntaxhighlight>
|
|DART-MX8M-PLUS=
{{#ifeq: {{#var:HARDWARE_NAME}} | DART-MX8M-PLUS |
<syntaxhighlight lang="diff">
<syntaxhighlight lang="diff">
&usb_dwc3_0 {
&usb_dwc3_0 {
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};
};
</syntaxhighlight>
</syntaxhighlight>
|
|#default=
<syntaxhighlight lang="diff">
<syntaxhighlight lang="diff">
&usbotg1 {
&usbotg1 {
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};
};
</syntaxhighlight>
</syntaxhighlight>
}}}}
|VAR-SOM-AM62=
<syntaxhighlight lang="diff">
&usb0 {
+ dr_mode = "host";
#address-cells = <1>;
#size-cells = <0>;
usb-role-switch;
status="okay";
 
port@1 {
reg = <1>;
 
typec_hs: endpoint {
remote-endpoint = <&usb_con_hs>;
};
};
};
</syntaxhighlight>
}}


If you build the kernel manually from source code, you should build ''only'' the device trees and copy them to your SD card or eMMC.<br>
If you build the kernel manually from source code, you should build ''only'' the device trees and copy them to your SD card or eMMC.<br>
<br>
<br>
Note: You can read the current dr_mode value on a running target, by executing the following command:
Note: You can read the current dr_mode value on a running target, by executing the following command:
{{#ifeq: {{#var:HARDWARE_NAME}} | DART-MX8M |
{{#switch: {{#var:HARDWARE_NAME}}
| DART-MX8M=
<pre>
# cat /sys/firmware/devicetree/base/usb@38100000/dwc3/dr_mode;
</pre>
| DART-MX8M-PLUS=
<pre>
# cat /sys/firmware/devicetree/base/usb@32f10100/dwc3@38100000/dr_mode;
</pre>
| VAR-SOM-MX93=
<pre>
# cat /sys/firmware/devicetree/base/soc@0/usb@4c100000/dr_mode
</pre>
| VAR-SOM-AM62=
<pre>
<pre>
# cat /sys/firmware/devicetree/base/usb@38100000/dwc3/dr_mode; echo
# cat /sys/firmware/devicetree/base/bus@f0000/dwc3-usb@f900000/usb@31000000/dr_mode
</pre>
</pre>
|
| DART-MX95=
{{#ifeq: {{#var:HARDWARE_NAME}} | DART-MX8M-PLUS |
<pre>
<pre>
# cat /sys/firmware/devicetree/base/usb@32f10100/dwc3@38100000/dr_mode; echo
/sys/firmware/devicetree/base/soc/usb@4c010010/usb@4c100000/dr_mode
</pre>
</pre>
|
| #default=
<pre>
<pre>
# cat /sys/firmware/devicetree/base/usb@32e40000/dr_mode; echo
# cat /sys/firmware/devicetree/base/usb@32e40000/dr_mode;
</pre>
</pre>
}}}}
}}


= Using the USB OTG port under Linux =
= Using the USB OTG port under Linux =
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For example, there is an Ethernet gadget module called g_ether, a mass storage gadget called g_mass_storage, a serial gadget called g_serial, etc.<br>
For example, there is an Ethernet gadget module called g_ether, a mass storage gadget called g_mass_storage, a serial gadget called g_serial, etc.<br>
<br>
<br>
Example using the g_mass_storage module to expose the root partition on eMMC to a PC while booting from recovery SD card:<br>
===Examples===
Connect a type-C plug to Standard-A plug cable between the board and a PC, and run the following on the board:
 
Connect a type-C plug to Standard-A plug cable between the board and a host PC, and run the following examples on the target board:  
 
==== Mass Storage Device ====
The following uses the g_mass_storage module to expose the root partition on eMMC to a PC while booting from recovery SD card:<br>
  # umount /dev/{{#var:EMMC_ROOTFS_DEV}}p1
  # umount /dev/{{#var:EMMC_ROOTFS_DEV}}p1
  # modprobe g_mass_storage file=/dev/{{#var:EMMC_ROOTFS_DEV}}p1
  # modprobe g_mass_storage file=/dev/{{#var:EMMC_ROOTFS_DEV}}p1
</pre>
 
The partition should be loaded on the PC as a mass storage device.
The partition should be loaded on the PC as a mass storage device.
==== USB Debug Console ====
The following uses the g_serial module to spawn a new debug console over USB:
On target:
# echo g_serial > /etc/modules-load.d/g_serial.conf      # Load g_serial module on boot
# sudo systemctl enable getty@ttyGS0.service              # Spawn a new tty session on ttyGS0
# reboot                                                  # Reboot to take effect
On Host:
$ minicom -D /dev/ttyACM0                                # Launch minicom on Host computer to login to target tty console
}}
}}
==== Ethernet Device ====
The following uses the g_ether to establish an ethernet link with a host computer over USB.
First, connect a USB cable from a host computer to the USB OTG port of the target. Then run the following commands:
On the target:
Load the g_ether module, assigning the host mac address 02:00:00:00:00:01
Note: you may exclude the host_addr argument, it's used here because the host computer will rename usb0 to enx020000000001
# modprobe g_ether host_addr=02:00:00:00:00:01
Tell NetworkManager not to manage this interface (skip this step if NetworkManager is not running on the target)
# nmcli dev set usb0 managed no
Assign a static IP address of 192.168.10.2
# ip addr flush usb0; ip addr add 192.168.10.2/24 dev usb0; ip link set usb0 up
On the host computer:
Tell NetworkManager not to manage this interface (skip this step if NetworkManager is not running on the host)
# nmcli dev set enx020000000001 managed no
Assign a static IP address of 192.168.10.1
$ sudo ip addr flush enx020000000001; sudo ip addr add 192.168.10.1/24 dev enx020000000001; sudo ip link set enx020000000001 up
Ping the target from the host:
$ ping 192.168.10.2 -c 3
PING 192.168.10.2 (192.168.10.2) 56(84) bytes of data.
64 bytes from 192.168.10.2: icmp_seq=1 ttl=64 time=0.931 ms
64 bytes from 192.168.10.2: icmp_seq=2 ttl=64 time=0.822 ms
64 bytes from 192.168.10.2: icmp_seq=3 ttl=64 time=0.777 ms
--- 192.168.10.2 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2032ms
rtt min/avg/max/mdev = 0.777/0.843/0.931/0.064 ms


== As OTG ==
== As OTG ==

Latest revision as of 10:04, 16 July 2024

Warning: This page is designed to be used with a 'release' URL parameter.

This page is using the default release RELEASE_SUMO_V1.0_DART-MX8M.
To view this page for a specific Variscite SoM and software release, please follow these steps:

  1. Visit variwiki.com
  2. Select your SoM
  3. Select the software release
DART-MX8M USB OTG

Configuring the USB OTG port under Linux

By default, the USB OTG port is configured as OTG in the device tree, and a USB type-C receptacle is assembled on the DART-MX8M custom board.
To use it as host only or peripheral only you need to change the value of the dr_mode property under the USB node in the device tree.
dr_mode: One of "host", "peripheral" or "otg". Defaults to "otg"

For example:
Follow either the "Build the Linux kernel from source code" or "Customizing the Linux kernel" Wiki pages and edit the following device tree file:
arch/arm64/boot/dts/freescale/fsl-imx8mq-var-dart-common.dtsi

&usb_dwc3_0 {
	status = "okay";
	extcon = <&typec_ptn5150>;
-	dr_mode = "otg";
+	dr_mode = "host";
};

If you build the kernel manually from source code, you should build only the device trees and copy them to your SD card or eMMC.

Note: You can read the current dr_mode value on a running target, by executing the following command:

# cat /sys/firmware/devicetree/base/usb@38100000/dwc3/dr_mode;

Using the USB OTG port under Linux

As host (default)

USB host

As peripheral

In order to use the board as a peripheral, an appropriate module needs to be loaded.
For example, there is an Ethernet gadget module called g_ether, a mass storage gadget called g_mass_storage, a serial gadget called g_serial, etc.

Examples

Connect a type-C plug to Standard-A plug cable between the board and a host PC, and run the following examples on the target board:

Mass Storage Device

The following uses the g_mass_storage module to expose the root partition on eMMC to a PC while booting from recovery SD card:

# umount /dev/mmcblk0p1
# modprobe g_mass_storage file=/dev/mmcblk0p1

The partition should be loaded on the PC as a mass storage device.

USB Debug Console

The following uses the g_serial module to spawn a new debug console over USB:

On target:

# echo g_serial > /etc/modules-load.d/g_serial.conf       # Load g_serial module on boot
# sudo systemctl enable getty@ttyGS0.service              # Spawn a new tty session on ttyGS0
# reboot                                                  # Reboot to take effect

On Host:

$ minicom -D /dev/ttyACM0                                 # Launch minicom on Host computer to login to target tty console

Ethernet Device

The following uses the g_ether to establish an ethernet link with a host computer over USB.

First, connect a USB cable from a host computer to the USB OTG port of the target. Then run the following commands:

On the target:

Load the g_ether module, assigning the host mac address 02:00:00:00:00:01
Note: you may exclude the host_addr argument, it's used here because the host computer will rename usb0 to enx020000000001
# modprobe g_ether host_addr=02:00:00:00:00:01

Tell NetworkManager not to manage this interface (skip this step if NetworkManager is not running on the target)
# nmcli dev set usb0 managed no

Assign a static IP address of 192.168.10.2
# ip addr flush usb0; ip addr add 192.168.10.2/24 dev usb0; ip link set usb0 up

On the host computer:

Tell NetworkManager not to manage this interface (skip this step if NetworkManager is not running on the host)
# nmcli dev set enx020000000001 managed no

Assign a static IP address of 192.168.10.1
$ sudo ip addr flush enx020000000001; sudo ip addr add 192.168.10.1/24 dev enx020000000001; sudo ip link set enx020000000001 up

Ping the target from the host:

$ ping 192.168.10.2 -c 3
PING 192.168.10.2 (192.168.10.2) 56(84) bytes of data.
64 bytes from 192.168.10.2: icmp_seq=1 ttl=64 time=0.931 ms
64 bytes from 192.168.10.2: icmp_seq=2 ttl=64 time=0.822 ms
64 bytes from 192.168.10.2: icmp_seq=3 ttl=64 time=0.777 ms

--- 192.168.10.2 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2032ms
rtt min/avg/max/mdev = 0.777/0.843/0.931/0.064 ms

As OTG

With OTG, the board can be either a host, or a peripheral.
In order to use it as a host and connect a peripheral (e.g. a USB flash drive) to it, either use a peripheral with type-C connector or use type-C to type-A adapter.
In order to use it as a peripheral and connect it to a PC, for example, a cable with a type-C plug on one end and a Standard-A plug on the other is needed.