On Mon, 2016-02-15 at 16:43 -0800, Greg KH wrote: > On Tue, Feb 16, 2016 at 12:37:57AM +0000, fx IWATA NOBUO wrote: > > My requirement is more device can be attached than 31 to connect > > many IoT devices. > > That's an odd requirement to use the USB protocol for, especially when > that is a hard-coded restriction in the USB protocol from what I > recall. No. It depends on the version. For 3.x the limit is 16 (4 bit in the routing string); for 2.x the limit is 255. (bNbrPorts in the hub descriptor) 31 is indeed the hard-coded limit for endpoints. [..] > > This patch: > > Default is 31. Changeable by -DVHCI_NPORTS up to USB_MAXCHILDREN. > > Negative in previous e-mail, so I may change 8. > > To reduce most outstanding overhead - event threads for each port, > > I made patch 2/2. Maybe your problem is that you have a thread for each port? Children of the same hub share resources of the hub and are on the same bus. If the bus is virtual these restrictions don't apply, so do you really want them to appear to be on the same hub? Regards Oliver -- 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
