Re: [PATCH v2 6/9] usb: misc: qcom_eud: add host mode coordination

[Konrad Dybcio]

On 2/9/26 6:37 PM, Elson Serrao wrote:
> 
> 
> On 2/4/2026 5:29 AM, Konrad Dybcio wrote:
>> On 1/27/26 12:38 AM, Elson Serrao wrote:
>>> EUD functions by presenting itself as a USB device to the host PC for
>>> debugging, making it incompatible in USB host mode configurations.
>>> Enabling EUD, when in host mode can also cause the USB controller to
>>> misbehave as the EUD hub can only have one upstream facing port.
>>
>> Perhaps that's a silly idea, but would the device itself see
>> the debug hub, being able to essentially self-debug in a way?
>>
> 
> This isn’t supported by the current hardware topology.
> 
> When EUD is enabled, it enumerates as a USB device to an external host via its
> upstream-facing port, while the SoC USB controller sits behind the hub’s
> downstream-facing port. As a result, the controller cannot enumerate or
> interact with the EUD device itself, and host mode is mutually exclusive with
> EUD debug on this path.

OK, I see. Thanks

Konrad