On Fri, Nov 20, 2015 at 11:13:00AM -0500, Alan Stern wrote: > On Fri, 20 Nov 2015, Peter Chen wrote: > > > > > > Hi Alan, we have several designs that the on-board HUB need to > > > > > be reset by gpio pin and its clock is also from the board or > > > > > the SoC. Any suggestions how to add these platform information > > > > > for HUB device? > > > > > > > > How about putting it in the device tree? > > > > http://www.firmware.org/1275/bindings/usb/usb-1_0.ps > > > > clocks and reset-gpios properties could be added to the USB hub node. > > > > > > Something like this is necessary. Instead of making the hub driver > > > take care of the reset gpio and the clock, I suggest you make the host > > > controller's platform driver do these things. > > > > > > This is because USB hubs are generic devices, not specific to any > > > platform and (usually) hot-pluggable. Associating platform-specific > > > data with a hub is out of the ordinary, and it deserves to be handled > > > by platform-specific code -- there is no such code in the hub driver. > > > > > > > If this on-board HUB is special, its reset pin needs to be toggled > > after power on, no matter for Intel or ARM platforms, how we handle > > it? It is not feasible we add this for all platform drivers. > > I don't know. Probably it should be handled the same way as any other > hardware with special requirements. > > Are you saying that it would be better to modify the hub driver than to > modify all the platform drivers? If you can figure out a way to make > it work, then maybe -- I don't see how to do it. > Yes, changing hub.c is hard, I am think if we can have a device driver for it, and this driver can be probed through special pid/vid, but I can't find a way to describe one USB device (eg, its external pins/clocks) through platform code, eg, dts or acpi. -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
