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cdc_ncm: toggle altsetting to force reset before setup

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[ 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Bjørn Mork 2016-03-03 22:20:53 +01:00 committed by Greg Kroah-Hartman
parent 32cb6781a9
commit 3aaa64b61a
1 changed files with 5 additions and 1 deletions
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6
drivers/net/usb/cdc_ncm.c
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@ -794,7 +794,11 @@ int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, u8 data_
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");