Xavier simple USB 2.0 device tree implemenation

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Xavier
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L4T release 32.7.1
Xavier AGX on custom carrier board

We have implemented a custom carrier for Xavier AGX and lead out a simple USB 2.0 port. The USB 2.0 port uses G10, USB3_N, and G11, USB3_P. GPIO 5 is used to enable USB power to the end device. I’m cannot share schematics on a public forum.

Device tree changes include:

  • removing USB 3.0 support as it is unused
  • setting usb2-0 to host mode as hardware doesn’t support OTG
  • removed ucsi_ccg nodes
  • removed typec extcon-cables
  • removed USB3 xusb_padctl support
  • deleting sata voltage regultors as they are unused:
    p2822_vdd_sata_1v5
    p2822_vdd_5v_sata
  • setting up the usb port to use a dummy regulator
  • hogging gpio 5 high, dap6_dout_pa1, to power devices

I’m seeing the USB driver fall into power save mode and never exit:
[ 14.354480] tegra-xusb 3610000.xhci: Upgrade port 0 to USB3.0
[ 14.354486] tegra-xusb 3610000.xhci: Upgrade port 1 to USB3.0
[ 14.453077] usb usb1: usb_suspend_both: status 0
[ 14.461181] usb usb2: usb_suspend_both: status 0
[ 14.557335] usbcore: registered new interface driver usbhid
[ 14.557337] usbhid: USB HID core driver
[ 16.356810] tegra-xusb 3610000.xhci: entering ELPG
[ 16.465854] tegra-xusb 3610000.xhci: entering ELPG done

What device tree changes am I missing to prevent the USB port from dropping into power save?

Thank you.

3

Hi,
The failure may be due to bad signal quality. You would need to do compliance test for the custom board. Please take a look at the tuning guide:
https://developer.nvidia.com/jetson-agx-xavier-series-tuning-and-compliance-guide-application-note

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Hi DaneLLL,

This isn’t a hardware issue; the problem is all device tree issues. We have tested the USB 2.0 hardware and gotten it working under certain cirmstances where we do not use a dummy regulator. We aren’t using the p2822_vdd_5v_sata regulator in our hardware design, so it’s disabled.

What causes the tegra-xusb driver to drop into and out of power save?

What is the correct way to hook in a dummy regulator to the USB port?

Are there any CBoot boot/power DTB changes necessary to set up a dummy regulator on the USB port?

Thanks.

5

Hi,
Please check [USB Lane Mapping] section in adaptation guide. You would need to set up vbus-supply like:

                ports {
                        usb2-0 {
                               status = "okay";
                               mode = "host";
                              vbus-supply = <&__usb_vbus_supply__>; // set up vbus supply
                        };
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DaneLLL. Thanks. We’ll look at the vbus-supply and do more testing.

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We got USB 2.0 working. All device tree issues:
1/ vbus-supply
2/ xusb_padctl

It took seeding the tegra xusb driver with printk’s to see how the device tree was being parsed and get details on errors.

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