How does one get an STM32G4 MCU into USB TEST_PACKET mode?

[CMitc.1]

How does one set an STM32G4 MCU into a USB test mode? The reference manual (RM0440) does not indicate any way to do this.

On the F4 series this could be done through the OTG_FS_HPRT register's PTCTL field.

I need to be able to get a peripheral (NOT a host) device upstream facing port into USB 2.0 Test_Packet mode for eye diagram testing.

[Bob S]

The G4 series have "device only" USB interfaces, not OTG. At least as far as I'm aware. So they don't support being the host and having peripherals connected to them.

[CMitc.1]

Of course not. I'm not asking to make it an OTG interface, I'm asking how to get it into test mode Test_Packet as specified in USB 2.0 section 7.1.20 Test Mode Support. The F4 series did that through OTG registers for some reason, but these test modes are NOT specific to hosts. I suspect it's simply not possible, as FS devices don't seem to need to support them.