Re: [PATCH v10 2/7] usb: mux: add generic code for dual role port mux

Roger Quadros
2016-06-07T12:49:24Z

On 07/06/16 12:27, Lu Baolu wrote:
> Hi,
>
> On 06/07/2016 02:34 PM, Jun Li wrote:
>>>> On 06/07/2016 11:03 AM, Jun Li wrote:
>>>>>> Hi Roger
>>>>>>
>>>>>>>>
>>>>>>>> For Mux devices implementing dual-role, the mux device driver _must_
>>>>>>>> use OTG/dual-role core API so that a common ABI is presented to user
>>>>>>>> space for OTG/dual-role.
>>>>>> That's the only point we have concern, do dual role switch through
>>>>>> OTG/dual-role core, not do it by itself.
>>>>
>>>> That really depends on how do you define "dual role". Can you please
>>>> provide an unambiguous definition of "dual role" used in OTG/dual-role
>>>> framework?
>> Host and peripheral.
>>
>
> This is definitely ambiguous.
>
> By reading OTG/dual-role code, my understanding is that "dual-role" is a
> "reduced OTG" which is for DRD devices lacking of some OTG negotiation
> protocols.

DRD means dual role with zero OTG features, which is similar to just host and
peripheral mode.

>
> We really can't say "it's the scope of OTG/dual-role" whenever it comes to
> "host and peripheral".

What other combination you foresee?

cheers,
-roger