On Fri, Aug 14, 2015 at 10:26:35AM -0400, Alan Stern wrote:
> On Fri, 14 Aug 2015, Peter Chen wrote:
>
> > > In the old days, a single device could be a USB host controller and
> > > nothing else. Then later, a single device could be either a host
> > > controller or a device controller. Now a single device can be both.
> > >
> > > Obviously this causes problems for our original design, where the
> > > device's drvdata stored a pointer to the hcd structure or the udc
> > > structure.
> > >
> > > In principle, the drvdata should point to something that contains
> > > pointers to both the hcd and udc structures. Maybe also an otg
> > > structure. That would require a lot of changes to existing code but it
> > > might be worthwhile.
> > >
> >
> > Yes, the core device drvdata should contain standard hcd, gadget,
> > otg structure together. Currently, the gadget is child device
> > for core device, it is reasonable the same for hcd, and we can
> > create device for chipidea host to achieve it. The dwc3 driver
> > does the similar things.
> >
> > Below is the reference device hierarchy for current IP driver:
> >
> > Glue Layer Device
> > |
> > |
> > |
> > IP Core Device
> > |
> > |----|----|
> > | | |
> > Gadget hcd otg
> >
> > Alan/Felipe, what do you think?
>
> That's not quite what I had in mind. I was thinking of something more
> like this:
>
> Platform device ---- drvdata ----> struct usb_pointers
> |
> |
> |-------|-------|
> | | |
> gadget hcd otg
>
> where struct usb_pointers (maybe you can think of a better name) looks
> like this:
>
> struct usb_pointers {
> struct usb_hcd *hcd;
> struct usb_gadget *gadget;
> struct usb_otg *otg;
> };
>
> If you want, you can use your IP Core device in place of my platform
> device. All that matters is that the parent device of the root hub
> (for hosts) or gadget (for peripherals) should store the address of a
> usb_pointers structure in its drvdata.
that looks pretty clean to me, Alan. Wonder how that looks after
actually implementing it.
--
balbi
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