cdc_ncm: toggle altsetting to force reset before setup

commit 48906f62c96cc2cd35753e59310cb70eb08cc6a5 upstream.

Some devices will silently fail setup unless they are reset first.
This is necessary even if the data interface is already in
altsetting 0, which it will be when the device is probed for the
first time.  Briefly toggling the altsetting forces a function
reset regardless of the initial state.

This fixes a setup problem observed on a number of Huawei devices,
appearing to operate in NTB-32 mode even if we explicitly set them
to NTB-16 mode.

Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 43afde8f48d23e2cc3ee15e4cc55bd298b45dfe4..74581cbcafa70d74fe75211d84308e8cc209231a 100644 (file)
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -464,7 +464,11 @@ advance:
 
        iface_no = ctx->data->cur_altsetting->desc.bInterfaceNumber;
 
-       /* reset data interface */
+       /* Reset data interface. Some devices will not reset properly
+        * unless they are configured first.  Toggle the altsetting to
+        * force a reset
+        */
+       usb_set_interface(dev->udev, iface_no, data_altsetting);
        temp = usb_set_interface(dev->udev, iface_no, 0);
        if (temp)
                goto error2;