Re: [PATCH] usb: typec: hd3ss3220: Add sysfs attribute for USB role state

[Heikki Krogerus]

> The HD3SS3220 driver correctly detects USB Type-C cable attach/detach
> events and propagates the role to the USB controller. However, there is
> no way for userspace to query the current role state (device/host/none).
>
> This becomes problematic when using udev rules to trigger scripts on
> role changes. The driver generates kobject change events, but the event
> itself doesn't contain the role information. Userspace needs to read
> the current state to determine the appropriate action.
>
> Add a 'usb_role' sysfs attribute that exposes the current USB role as
> a string ("device", "host", or "none"). Also ensure sysfs_notify() and
> kobject_uevent() are called when the role changes, enabling userspace
> applications to poll() on the sysfs file or receive udev events.
>
> This is useful for systems that need to:
> - Start/stop USB gadget functions based on cable connection
> - Switch between host and device modes dynamically
> - Monitor USB Type-C port state from userspace
You use the "data_role" sysfs attribute file for this.

--
heikki