Re: [PATCH v3 1/1] USB: core: let USB device know device node

Peter Chen
2016-01-20T12:50:26Z

On Wed, Jan 20, 2016 at 10:07:13AM +0100, Arnd Bergmann wrote:
> On Wednesday 20 January 2016 11:48:39 Peter Chen wrote:
> > >
> > > > Alternatively, you could use one of the high bits of the 'reg' value
> > > > to indicate which root hub is used. I'm sure that would work as
> > > > well, but be less obvious.
> > >
> > > It's probably best to stick with the same numbering that the hardware
> > > uses.
> >
> > Seems we are talking about root hub, not the device in the
> > root hub. So for multiple ports controller, we have to own node for
> > root hub. Assume your example, there is a genesys HUB at physical
> > port 1, I suggest a dts node description like below, please correct
> > me if anything wrong.
> >
> > &usb1 {
> > roothub_1: nxp@1 {
> > compatible = "usb15a2,007d";
> > reg = <0x01>;
> >
> > hub: genesys@1 {
> > compatible = "usb05e3,0608";
> > reg = <0x01>;
> > };
> > };
> >
> > roothub_2: nxp@2 {
> > compatible = "usb15a2,007d";
> > reg = <0x02>;
> > };
> >
> > ...
> >
> > roothub_7: nxp@7 {
> > compatible = "usb15a2,007d";
> > reg = <0x07>;
> >
> > hub: genesys@1 {
> > compatible = "usb05e3,0608";
> > reg = <0x01>;
> > };
> > };
> >
> > ...
> >
> > roothub_9: nxp@9 {
> > compatible = "usb15a2,007d";
> > reg = <0x09>;
> > };
> > };
>
> This looks wrong to me: if I understand it right, you are now modeling
> each port of the root hub as a separate hub, so you end up with
> a total of 11 hub nodes when there should only be one or two.
>

How about below from both driver and device tree view:

1. From the USB driver view

USB Controller
|
|
---------------------|----------------
| |
root hub(HS) root hub(SS, optional)
| |
--------------------- -------------------------
| | ... | | | |
port 1 port 2 port 6 port 1 port 2 port 3
| |
genesys hub (if HS) genesys hub (if SS)

2. dts node:

&usb1 {
port_1: nxp@1 {
compatible = "usb15a2,007d";
reg = <0x01>;

hub: genesys@1 {
compatible = "usb05e3,0608";
reg = <0x01>;
};
};

port_2: nxp@2 {
compatible = "usb15a2,007d";
reg = <0x02>;
};

...

port_7: nxp@7 {
compatible = "usb15a2,007d";
reg = <0x07>;

hub: genesys@1 {
compatible = "usb05e3,0608";
reg = <0x01>;
};
};

...

port_9: nxp@9 {
compatible = "usb15a2,007d";
reg = <0x09>;
};
};

- If the above are ok, is it ok we add two nodes for the same device
in case the speed negotiation is different at some situations?
- Usually, it should be ok we only add nodes at device tree which
the hard wired device on it, like port_1 and port 7 at above, right?

--

Best Regards,
Peter Chen