AM67A: Implementing USB_ID on a custom design

Stephen,

For the AM67A, the Linux s/w tells the host or peripheral mode without an external switch setting letting the s/w know what mode to configure.

So the TRM statement - "USB operational mode identifier. This functionality is supported via
GPIO." Is incorrect?.  

TRM is correct in saying the GPIO is supported by the SoC.

If someone implements a connector with an ID pin, that pin needs to get connected to a GPIO and mapped as such in the DTS.

Hi ShreyasRao,

Do you have an example of this DTS file mapping?. 

thanks

Thanks for the DTB fragment, however I do not see any GPIO mapping?. 

I'm also looking at the schematics of the AM67x EVM and can't figure out how USB_ID info gets back to the processor?.

thanks

In J722S EVM , we have the TUSB321 for logic control of the type-C port mode selection. The dip switch set to select DRD mode.

ShreyasRao said:

In J722S EVM , we have the TUSB321 for logic control of the type-C port mode selection. The dip switch set to select DRD mode.

Right, but how does the AM67x know what mode (UFP/DFP) the USB port is in?

Stephen,

Not sure I understand.

The device's Linux s.w driver can be set to host or device mode or both. The USB_port_sel on the EVM switch setting can be configured such that the device can be in host or device or both.

Stephen Turner said:

Right, but how does the AM67x know what mode (UFP/DFP) the USB port is in?

My understanding is that the SDK hardcodes the port role in software using DTS. The mode set in the DTS has to agree with the dip switch on the EVM.TUSB321 can be setup for dual role by leaving the PORT pin of unconnected, then the ID pin could (should?) be used for role-switching. This seems relevant:

https://github.com/torvalds/linux/blob/18daea77cca626f590fb140fc11e3a43c5d41354/Documentation/devicetree/bindings/connector/usb-connector.yaml#L54

but `id-gpios` seems to be supported only when `usb-b-connector` is used because `gpio-usb-b-connector` and `usb-c-connector` appear to be mutually exclusive according to the above DTS schema. Looking at the linux source code I could not find any example of `id-gpios` usage with `usb-c-connector`.

Also in the TRM the table "12.2.4.1.2 USB Not Supported Features" lists "OTG Protocol is not supported for USB Type-C applications" and I am not sure what the implications are.