From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?utf-8?Q?Bj=C3=B8rn_Mork?= Subject: Re: [PATCH net] net: cdc_ncm: workaround for missing CDC Union Date: Fri, 18 Jan 2013 22:17:03 +0100 Message-ID: <871udiur74.fsf@nemi.mork.no> References: <1358519147-10073-1-git-send-email-bjorn@mork.no> <22276933.xSGyXJfOvq@linux-5eaq.site> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Greg Suarez , Alexey Orishko To: Oliver Neukum Return-path: In-Reply-To: <22276933.xSGyXJfOvq-7ztolUikljGernLeA6q8OA@public.gmane.org> (Oliver Neukum's message of "Fri, 18 Jan 2013 20:11:25 +0100") Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org Oliver Neukum writes: > On Friday 18 January 2013 15:25:47 Bj=C3=B8rn Mork wrote: >> Adding support for the MBIM mode in some Sierra Wireless devices. >>=20 >> 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 som= e of the more hairy vendor specific control message parts if you provide one: http://msdn.microsoft.com/en-us/library/windows/hardware/mbim-based-mob= ile-broadband-requirements-for-windows.aspx But they should of course provide the CDC Union functional descriptor a= s well, even if that is "just" a USB-IF requirement and not a Windows requirement ;-) Bj=C3=B8rn -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html