Commit 48906f62 authored Mar 03, 2016 by Bjørn Mork Committed by David S. Miller Mar 07, 2016

cdc_ncm: toggle altsetting to force reset before setup



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>

parent 1666984c

drivers/net/usb/cdc_ncm.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -837,7 +837,11 @@ 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");