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

Peter Chen
2016-01-21T03:15:24Z

On Wed, Jan 20, 2016 at 03:19:36PM +0100, Arnd Bergmann wrote:
> On Wednesday 20 January 2016 20:50:26 Peter Chen wrote:
> > 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?
>
> This looks identical to the version before, what is the difference?
>

Just adding from device driver view and change the name from "roohub" to
"port".

It is the port number (1-9), but not the root hub number.

At the most of embedded platforms, we have only one port per controller.
For example, at the non-hub boards, if there are two Standard-A ports,
there are from two different USB controllers.
But for Alan's case, it has six ports, and all from the one USB controller,
port 1 to port 6 are from the HS root hub, port 7 to port 9 are from the SS
root hub.

For the single port controller platform, the dts will be like below, port_1 is
under the HS root hub, port_2 is under the SS root hub.

&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>;

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

--

Best Regards,
Peter Chen