From 48906f62c96cc2cd35753e59310cb70eb08cc6a5 Mon Sep 17 00:00:00 2001 From: Bjørn Mork Date: Thu, 3 Mar 2016 22:20:53 +0100 Subject: 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 Signed-off-by: David S. Miller --- drivers/net/usb/cdc_ncm.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c index dc0212c3cc28..be927964375b 100644 --- a/drivers/net/usb/cdc_ncm.c +++ b/drivers/net/usb/cdc_ncm.c @@ -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"); -- cgit v1.2.3-55-g7522