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SubjectRe: [PATCH v4 07/13] usb: otg: add OTG core
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(adding back folks in cc)

On 08/09/15 20:35, Alan Stern wrote:
> On Tue, 8 Sep 2015, Roger Quadros wrote:
>
>>>> What if there is another architecture like so?
>>>>
>>>> C:
>>>> [Parent]
>>>> |
>>>> |
>>>> |------------------|--------------|
>>>> [OTG core] [gadget] [host]
>>>>
>>>> We need a more flexible mechanism to link the gadget and
>>>> host device to the otg core for non DT case.
>>>>
>>>> How about adding struct usb_otg parameter to usb_otg_register_hcd()?
>>>>
>>>> e.g.
>>>> int usb_otg_register_hcd(struct usb_otg *otg, struct usb_hcd *hcd, ..)
>>>>
>>>> If otg is NULL it will try DT otg-controller property or parent to
>>>> get the otg controller.
>>>
>>> This seems a lot like something Peter and I discussed recently. See
>>>
>>> http://marc.info/?l=linux-usb&m=143977568021328&w=2
>>>
>>> and the following messages in that thread.
>>>
>>
>> If I understood right, your proposal was to add a usb_pointers data
>> struct to the device's drvdata?
>
> Right.
>
>> This is fine only if the otg/gadget/host share the same device.
>> It does not solve the problem where each have different platform devices.
>
> Why not? Each of the platform devices can store a pointer to the same
> usb_pointers structure. Wouldn't that be suitable?
>

I didn't understand how all of them get the reference to the
same usb_pointer structure (or contents) when their respective platform devices
get created so that they can store it in their respective drvdata.

Worst case, the 3 devices could be totally independent of each other without a
common parent, and get registered at different times.

The common resource here is the physical USB port for which the 3 drivers
otg/host/gadget are being registered.
There should be a mechanism for each device to tell that it is part of
this particular USB port. (or usb_pointers struct)

cheers,
-roger


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