Re: Non-enumerable devices on USB and other enumerable buses

[Mark Brown]

On Wed, Aug 14, 2013 at 08:16:56PM +0000, Paul Zimmerman wrote:

> Mark's original complaint about USB was this:
> 
> > the device).  The hub needs to be "plugged" into the SoC after the SoC
> > USB controller has started with some GPIOs so we need to tell the system
> > that the hub exists and needs to be synchronised with the USB controller.

> This sounds to me like the normal discovery mechanism for USB isn't getting
> kicked off because no Connect Status Change is being triggered on the root
> port when the hub is brought online using the GPIOs. Maybe the port has
> been runtime suspended because no device was attached originally?

> So maybe the only thing needed for USB is a way to tell the parent port to
> frob its port control bits to try to determine if a device is now present.
> (set Wake on Connect Enable? Do a Port Reset? Cycle the Port Power bit if
> possible?)

No, that's not required in this case - the case is the opposite one to
the one you describe.  Host starting first then hub works fine, if the
host does go into a low power mode it seems to notice the hub appearing
just fine.  Hub then host fails for some reason which I don't know.

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