I'm working on a device design that operates in USB-C alternate mode as a displayport dongle. As such it requires a USB 2.0 billboard device to be present to negotiate with the host and enter alt mode.
This might be a silly question but if after the device enters alt mode, I want to turn the USB 2.0 connection over to another device (using a USB Mux), can I disconnect the billboard and then point to my other USB device without losing Alt Mode function? Or will alt mode cease function when the Billboard is disconnected?
In the USB-C Spec from August 2019, the following is stated
E.4.3 Operational Summary:
Host stays in USB DisplayPort Dock mode until
a. Explicitly exited by and Exit Mode VDM.
b. System physically disconnected from the USB DisplayPort Dock
c. Hard Reset on USB PD
d. VBus is removed
Would (b) count as physical device removal? Or is it referring to the USB-C connection and not the USB 2.0 Billboard Interface?
Thanks for the help!