On Sun, 14 Mar 2010, Hans de Goede wrote: > Hi, > > The attached patch adds a new usb device quirk > USB_QUIRK_HONOR_BNUMINTERFACES, when this quirk is set and a device > has more interface descriptors in a configuration then it claims to > have in config->bNumInterfaces, ignore all additional interfaces. > > This is needed for devices which try to hide unused interfaces by only > lowering config->bNumInterfaces, and which can't handle if you try to talk > to the "hidden" interfaces. > > This patch also adds a quirk table entry for one such device, which existence > is the reason for this patch. The problem with this patch is that it assumes the "hidden" interfaces are always the last ones in the descriptor listing. That's not necessarily true; devices don't have to list their interfaces in any particular order. If instead you decide that the "hidden" interfaces are the ones with bInterfaceNumber >= bNumInterfaces, then you face possible problems with devices that leave gaps in the series of bInterfaceNumber values. I don't know whether any such devices exist, but they might. 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
