Oliver Neukum <oliver@xxxxxxxxxx> writes: > On Friday 18 January 2013 15:25:47 Bjørn Mork wrote: >> Adding support for the MBIM mode in some Sierra Wireless devices. >> >> Some Sierra Wireless firmwares support CDC MBIM but have no CDC >> Union funtional descriptor. This violates the MBIM specification, >> but we can easily work around the bug by looking at the Interface >> Association Descriptor instead. This is most likely what >> Windows uses too, which explains how the firmware bug has gone >> unnoticed until now. > > Should we do this for everything CDC? I don't know. There are workarounds for missing CDC Union descriptors on RNDIS devices in cdc_ether.c, but I have no idea if those devices in provide an IAD instead. I don't think this bug is a very common. MBIM devices are likely to have IADs because Microsoft let you skip some of the more hairy vendor specific control message parts if you provide one: http://msdn.microsoft.com/en-us/library/windows/hardware/mbim-based-mobile-broadband-requirements-for-windows.aspx But they should of course provide the CDC Union functional descriptor as well, even if that is "just" a USB-IF requirement and not a Windows requirement ;-) Bjørn -- 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
