R-Car/How-to-describe-device-tree-for-R-Car-Gen3-USB2-DRD-channel

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Overview

When we would like to use a USB2.0 DRD channel of R-Car Gen3 SoCs, the following device nodes require "dr_mode" properties in your device tree. Otherwise, since phy-rcar-gen3-usb2.c driver doesn't initialize specific registers, the USB2.0 channel doesn't work correctly.

  • ehci0
  • ohci0
  • hsusb
  • ehci3 (if r8a77951)
  • ohci3 (if r8a77951)
  • hsusb3 (if r8a77951)

A "dr_mode" property can have "otg", "host" or "peripheral".

Optional property "renesas,no-otg-pins"

We can set "renesas,no-otg-pins" to the following device nodes to avoid checking of ID pins for "host" or "peripheral" mode.

  • usb2_phy0
  • usb3_phy3 (if r8a77951)

Summary

dr_mode Initial mode Reference
"otg" Act as host or peripheral (depends on ID signal) salvator-common.dtsi, r8a77951-salvator-xs.dts
"host" Act as host r8a77995-draak.dts
"peripheral" Act as peripheral n/a
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