Re: [PATCH net-next v3] cdc_ether: Improve ZTE MF823/831/910 handling

From: Kristian Evensen <redacted>
Date: Tue, 19 Jul 2016 16:54:11 +0200

The firmware in several ZTE devices (at least the MF823/831/910
modems/mifis) use OS fingerprinting to determine which type of device to
export. In addition, these devices export a REST API which can be used to
control the type of device. So far, on Linux, the devices have been seen as
RNDIS or CDC Ether.

When CDC Ether is used, devices of the same type are, as with RNDIS,
exported with the same, bogus random MAC address. In addition, the devices
(at least on all firmware revisions I have found) use the bogus MAC when
sending traffic routed from external networks. And as a final feature, the
devices sometimes export the link state incorrectly. There are also
references online to several other ZTE devices displaying this behavior,
with several different PIDs and MAC addresses.

This patch tries to improve the handling of ZTE devices by doing the
following:

Please fix these warnings and resubmit:

  CC [M]  drivers/net/usb/cdc_ether.o
drivers/net/usb/cdc_ether.c: In function ‘usbnet_cdc_zte_rx_fixup’:
drivers/net/usb/cdc_ether.c:461:5: warning: unused variable ‘buggy_hwaddrs_idx’ [-Wunused-variable]
  u8 buggy_hwaddrs_idx = 0;
     ^
drivers/net/usb/cdc_ether.c:460:5: warning: unused variable ‘num_buggy_hwaddrs’ [-Wunused-variable]
  u8 num_buggy_hwaddrs;
     ^