From: Bjørn Mork Date: Thu, 3 Mar 2016 21:20:53 +0000 (+0100) Subject: cdc_ncm: toggle altsetting to force reset before setup X-Git-Tag: v3.16.35~19 X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0948b11f0938d509d86d81c1f56527a25b29ac31;p=linux cdc_ncm: toggle altsetting to force reset before setup [ 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 Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c index b7b3ed5f666c..58990934f192 100644 --- a/drivers/net/usb/cdc_ncm.c +++ b/drivers/net/usb/cdc_ncm.c @@ -815,7 +815,11 @@ 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");