RE: No carrier lost information with gadget RNDIS/ECM

[Kai Ruhnau]

Hi Peter,

>> 
>> > Do you have any components at VBUS?
>> 
>> There were ESD protection diodes that connected D+/D- with VBUS.  We 
>> removed those from the PCB and the problem is gone meaning VBUS 
>> discharges as expected, the controller runtime-suspends and ultimately 
>> systemd-networkd reports a lost carrier.
>> Those diodes haven't been a problem with 4.9, though. Did something change 
>> here?
>> I superficially looked at SRP, HNP and ADP, but nothing caught my eye...
>> 
> 
> You need to disable OTG stuffs at dts if OTG and OTG_FSM are enabled at 
> configuration.
> See below:
>
> 655 &usbotg1 {
> 656         vbus-supply = <&reg_usb_otg1_vbus>;
> 657         pinctrl-names = "default";
> 658         pinctrl-0 = <&pinctrl_usb_otg1_id>;
> 659         srp-disable;
> 660         hnp-disable;
> 661         adp-disable;
> 662         status = "okay";
> 663 };
>
> Is it available to share your USB part schematic?

We have decided to create a hardware revision. Things like the "USB Plugged-In 
Detector" that drive DP and DN high will charge up VBUS in our current design 
and are likely one of the (if not "the") contributing factors to the issue. I 
will ping back when we have the necessary components to test.

Thanks for your help, Peter!

Cheers,
Kai