On Tue, Feb 07, 2017 at 05:51:05PM +0100, John Skelton wrote: > Apologies if this ought to have gone to the USB maintainer (but his > auto-reply implies not). This is the correct place. > I'm particularly interested in drivers/usb/core/config.c > which appears to enforce the USB specification by refusing to allow a > low speed CDC ACM. (Comment "Some buggy low-speed devices ...", at > about line 300.) > > However, such devices exist and some are potentially quite useful (such > as Arduinos & digistump). Various people have posted about not being > able to use them with Linux and I think the above file is the reason > (another well known OS family allows them). > > I'd like to ask if there's a sane (Linux) way to allow them or are you > open to one being created? > > If so, as I don't know the best way then if you have any ideas I'd > certainly be pleased to hear them. Some sort of quirk? > > To make it easy for non-expert/novice Linux users to connect > non-conforming USB devices and have them "just work" please consider > a way that is either the default or easy, i.e. so they don't have to > config/build a kernel. > > I am a bit surprised that the code does what it currently does, as it > basically makes such devices unusable so far as I can tell and may as > well just reject them entirely. As Felipe points out, this is to try to help some obviously broken devices to work properly. We could take that code out and even more devices would stop working, but I think people would be upset at that :) What device out there that is so obviously incorrect that still doesn't work even with the workaround that that the kernel is trying to do? thanks, greg k-h -- 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
