[possibly theoretical issue] How should `selectAlternateInterface` handle running out of bandwidth?

[ArcaneNibble]

The WebUSB specification for the selectAlternateInterface function only describes the process of issuing a SET_INTERFACE control transfer. However, this functionality is often used for isochronous transfers which have reserved/guaranteed bandwidth on the bus. Because of this, operating systems typically require using a special function to do this (rather than issuing a raw control transfer) so that it can make sure the bus actually has sufficient bandwidth for the new configuration.

How should failures in this bandwidth allocation process be reported?

[reillyeon]

The Chromium implementation calls the OS-specific function rather than sending the SET_INTERFACE request directly so it will report an error if the OS determines the bandwidth limit has been reached. This should be normatively specified.