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    Subject[PATCH 3.19.y-ckt 07/66] cdc_ncm: toggle altsetting to force reset before setup
    Date
    3.19.8-ckt20 -stable review patch.  If anyone has any objections, please let me know.

    ---8<------------------------------------------------------------

    From: =?UTF-8?q?Bj=C3=B8rn=20Mork?= <bjorn@mork.no>

    [ Upstream commit 48906f62c96cc2cd35753e59310cb70eb08cc6a5 ]

    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: Kamal Mostafa <kamal@canonical.com>
    ---
    drivers/net/usb/cdc_ncm.c | 6 +++++-
    1 file changed, 5 insertions(+), 1 deletion(-)

    diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
    index c12ce3d..deacba3 100644
    --- a/drivers/net/usb/cdc_ncm.c
    +++ b/drivers/net/usb/cdc_ncm.c
    @@ -843,7 +843,11 @@ 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) {
    dev_dbg(&intf->dev, "set interface failed\n");
    --
    2.7.4
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