On Thu, Feb 14, 2013 at 12:15:10PM +0200, Felipe Balbi wrote: > Hi, > > On Thu, Feb 14, 2013 at 11:07:22AM +0100, Sascha Hauer 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. > > > > We have quite some boards on which the ID pin is not wired up, so if a > > core is both host and device capable there is no way to detect the > > wanted mode if not given from the devicetree. > > right, that's fair. But that doesn't mean board can't work as both, > right. The IP is still the same, just the board is wired differently ;-)
Yes, it is. Usually I run kernels with both host and device support enabled. Consider the IP is OTG capable, the chipidea driver will initialize both roles. Now if a board only supports one role and does not have an ID pin, how do I make sure the driver is in the correct mode? I need to specify it somehow. Otherwise I may end up on a host-only board with the driver sitting in device mode, or with a device-only board with the driver sitting in host mode. > > > > Maybe we can ignore dr_mode in host-only and device-only builds and only > > > look at it for DRD builds ? > > > > If something is or is not compiled in the kernel this doesn't mean the > > kernel > > is not started on boards with a different situation. > > who said kernel wouldn't start ? If you request a host-only build, you > need to force your IP into working as host, since that's all you have, > either that or you bail out on probe(). Let me clarify, I don't want to use Kconfig to specify my boards capabilities. If a kernel is compiled for host mode only and the devicetree specifies a port is device-only, then yes, the driver should bail out on probe, maybe leaving a message that it found a device for which the suitable role is not compiled in. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html