Re: [PATCH 1/2] dt: bindings: add allwinner,otg-routed property for phy-sun4i-usb

[Hans de Goede]

Hi,

On 09/21/2016 10:19 AM, Icenowy Zheng wrote:
> 21.09.2016, 15:10, "Hans de Goede" <hdegoede@xxxxxxxxxx>:
> > Hi,
> >
> > On 09/21/2016 10:04 AM, Icenowy Zheng wrote:
> > >  On some newer Allwinner SoCs (H3 or A64), the PHY0 can be either routed to
> > >  the MUSB controller (which is an OTG controller) or the OHCI/EHCI pair
> > >  (which is a Host-only controller, but more stable and easy to implement).
> > >
> > >  This property marks whether on a certain board which controller should be
> > >  attached to the PHY.
> > >
> > >  Signed-off-by: Icenowy Zheng <icenowy@xxxxxxxx>
> >
> > Erm, I think that the idea here is to dynamically switch the routing
> > based on the id-pin of the otg connector. IOW use the musb controller
> > for device mode, and the ehci/ohci proper for proper host support
> > when in host mode.
>
> At least on some boards this implementation works...
>
> (I mean Pine64, which has two USB-A connectors)

Right and I think it is great that you're working on this.

But even with an A connector on the board, we can still use the device
mode (e.g. the SoC's native FEL mode will be used this way).

Notice that you can fake id-pin changes by echoing a mode to:

/sys/devices/platform/soc@01c00000/1c13000.usb/musb-hdrc.1.auto/mode

Valid values to echo are: host, peripheral and otg.

If you combine this with using either an USB A<->A cable, or using
the port normally as a host you should be able to develop and test
full otg support.

Eventually we will need a full otg support rather then your current solution
and I'm afraid that your solution may get in the way of full otg support.

Regards,

Hans