On Tue, 19 Jan 2016, Arnd Bergmann wrote: > On Tuesday 19 January 2016 11:08:59 Peter Chen wrote: > > > > I am afraid I have no USB 3.0 PC running Linux. > > > > > > - Which the value of hub->descriptor->bNbrPorts for root hub? > > > > > > In the example above, the legacy root hub would have bNbrPorts set to 6 > > > and the SS root hub would have bNbrPorts set to 3. > > > > > > > Ok, so the maximum physical port number is 6 as well as bNbrports value. > > The "reg" value at dts should be from 1 to 6. "reg" stands for physical > > port number for individual physical port, eg if "reg" equals to 1, it > > stands for the device connects at port 1, no matter the device is HS or > > SS, it can use the node whose "reg" is 1. > > As I understand it, you could have two devices that are both > connected to port '1', when one is using HS and the other is using > SS. This means that we can't use the same 'reg' value for both, and > we have to define a particular way to disambiguate them. > > As Alan says, there is an established ordering that just sorts the > ports form 1 to 9 in the example, and that would be the most > straightforward to use here. There is even a documented callback (find_raw_port_number) in the hc_driver structure for converting between the numbering schemes. I don't know if all the existing USB-3 host controller drivers implement that callback, but they should. > 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. Alan Stern -- 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
