Not only legitimate, but required, depending on the class protocol. Best regards, --Terry
> -----Original Message----- > From: tech-kern-ow...@netbsd.org [mailto:tech-kern-ow...@netbsd.org] On > Behalf Of Greg Troxel > Sent: Wednesday, December 30, 2015 17:36 > To: Brian Buhrow <buh...@nfbcal.org> > Cc: Nick Hudson <nick.hud...@gmx.co.uk>; Nick Hudson <sk...@netbsd.org>; > tech-kern@NetBSD.org > Subject: Re: Potential problem with reading data from usb devices with > ugen(4) > > > Brian Buhrow <buh...@nfbcal.org> writes: > > > To answer your question about whether there is a standard for > > generating these packets, it seems there is not. Linux expects you to > > use an ioctl() to generate the packet while FreeBSD expects you to > > send a write request with 0 bytes, as we do with the ugen(4) changes I'm > making. > > I meant: in the USB specification, is it legitimate to do zero-length > transfer?
