[PATCH 3/9] USB: add devicetree helpers for determining dr_mode and phy_type

[Felipe Balbi]

On Thu, Feb 14, 2013 at 11:11:55AM +0100, Marc Kleine-Budde wrote:
> >>>> @@ -32,4 +35,37 @@ const char *usb_speed_string(enum usb_device_speed speed)
> >>>>  }
> >>>>  EXPORT_SYMBOL_GPL(usb_speed_string);
> >>>>  
> >>>> +#ifdef CONFIG_OF
> >>>> +static const char *usb_dr_modes[] = {
> >>>> +	[USB_DR_MODE_UNKNOWN]		= "",
> >>>> +	[USB_DR_MODE_HOST]		= "host",
> >>>> +	[USB_DR_MODE_PERIPHERAL]	= "peripheral",
> >>>> +	[USB_DR_MODE_OTG]		= "otg",
> >>>> +};
> >>>
> >>> It turns out this is a problem, especially since this is generic usb
> >>> code: we have a chipidea controller (a patchset just arrived) that does
> >>> both host and peripheral, but not otg. And I'm told now that dwc3
> >>> controller can be synthesized like that too.
> > 
> > I wonder if this part is really necessary. Usually you would read it
> > from HW's registers. For dwc3, it's quite recently that we allowed the
> > driver to be built with host-only, device-only or DRD functionality.
> 
> The imx25 USB version of the chipidea IP Core get's really confused if
> you read from the CAP_DCCPARAMS register on the host only port. In
> freescale's documentation the register is marked as reserved. The host
> port will not work then.

heh, nicely done.

> > Maybe we can ignore dr_mode in host-only and device-only builds and only
> > look at it for DRD builds ?
> > 
> >> You mean a single instance of the controller (i.e. USB port) is host and
> >> peripheral but has no otg registers. This means the mode of the port is
> >> configured by userspace via the debugfs file? Is this possible?
> > 
> > yes, it is possible. Dual-Role doesn't imply OTG, but OTG implies
> > Dual-Role.
> 
> Thanks for the info. Then we need a fourth value for the helper code.
> What's a sensible sting: "dual-role", "dr"?

dual-role.

-- 
balbi
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