Linux USB OTG: Difference between revisions
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--> {{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__ | ||
= Configuring the USB OTG port under Linux = | = 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 | By default, the USB OTG port is configured as OTG in the device tree, and a USB type-C receptacle is assembled on the {{#var:HARDWARE_NAME}} custom board.<br> | ||
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.<br> | 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.<br> | ||
dr_mode: One of "host", "peripheral" or "otg". Defaults to "otg"<br> | dr_mode: One of "host", "peripheral" or "otg". Defaults to "otg"<br> | ||
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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> | ||
{{#ifeq: {{#var:HARDWARE_NAME}}|DART-MX8M|{{#ifeq: {{#var:YOCTO_NAME}}|Morty|arch/arm64/boot/dts/variscite/imx8m-var-dart-common.dtsi|arch/arm64/boot/dts/freescale/{{#if: {{#var:DTB_PREFIX}} | {{#var:DTB_PREFIX}}.dtsi | fsl-imx8mq-var-dart-common.dtsi }}}}|{{#ifeq: {{#var:HARDWARE_NAME}}|DART-MX8M-MINI|arch/arm64/boot/dts/freescale/{{#if: {{#var:DTB_PREFIX}} | {{#var:DTB_PREFIX}}.dts | fsl-imx8mm-var-dart.dts }} for DART-MX8M-MINI, or arch/arm64/boot/dts/freescale/{{#if: {{#var:DTB_PREFIX}} | {{#var:DTB_PREFIX}}.dts | fsl-imx8mm-var-som.dts }} for VAR-SOM-MX8M-MINI| | |||
{{#ifeq: {{#var:HARDWARE_NAME}}|DART-MX8M-PLUS|arch/arm64/boot/dts/freescale/imx8mp-var-dart.dts for DART-MX8M-PLUS, or arch/arm64/boot/dts/freescale/imx8mp-var-som.dts for VAR-SOM-MX8M-PLUS| | |||
{{#ifeq: {{#var:HARDWARE_NAME}}|VAR-SOM-MX8M-NANO|freescale/{{#if: {{#var:DTB_PREFIX}} | {{#var:DTB_PREFIX}}.dts | fsl-imx8mn-var-som.dts }}}}}}}}}} <br> | |||
{{#ifeq: {{#var:HARDWARE_NAME}} | DART-MX8M | | {{#ifeq: {{#var:HARDWARE_NAME}} | DART-MX8M | | ||
<syntaxhighlight lang="diff"> | |||
&usb_dwc3_0 { | |||
status = "okay"; | |||
extcon = <&typec_ptn5150>; | |||
- dr_mode = "otg"; | |||
+ dr_mode = "host"; | |||
}; | |||
</syntaxhighlight> | |||
| | |||
{{#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> | ||
}} | }}}} | ||
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> | ||
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{{#ifeq: {{#var:HARDWARE_NAME}} | DART-MX8M | | {{#ifeq: {{#var:HARDWARE_NAME}} | DART-MX8M | | ||
<pre> | <pre> | ||
# cat /sys/firmware/devicetree/base/usb@38100000/dwc3/dr_mode; | # cat /sys/firmware/devicetree/base/usb@38100000/dwc3/dr_mode; | ||
</pre> | </pre> | ||
| | | | ||
{{#ifeq: {{#var:HARDWARE_NAME}} | DART-MX8M-PLUS | | |||
<pre> | <pre> | ||
# cat /sys/firmware/devicetree/base/usb@ | # cat /sys/firmware/devicetree/base/usb@32f10100/dwc3@38100000/dr_mode; | ||
</pre> | </pre> | ||
}} | | | ||
<pre> | |||
# cat /sys/firmware/devicetree/base/usb@32e40000/dr_mode; | |||
</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> | ||
===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 | ||
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 | |||
}} | }} | ||
Revision as of 19:59, 9 June 2022
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)
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
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.