net: cdc_ncm: fix control message ordering

This is a context modified revert of commit 6a9612e
("net: cdc_ncm: remove ncm_parm field") which introduced
a NCM specification violation, causing setup errors for
some devices. These errors resulted in the device and
host disagreeing about shared settings, with complete
failure to communicate as the end result.

The NCM specification require that many of the NCM specific
control reuests are sent only while the NCM Data Interface
is in alternate setting 0. Reverting the commit ensures that
we follow this requirement.

Fixes: 6a9612e ("net: cdc_ncm: remove ncm_parm field")
Reported-and-tested-by: Pasi Kärkkäinen <pasik@iki.fi>
Reported-by: Thomas Schäfer <tschaefer@t-online.de>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/cdc_ncm.c

@@ -68,7 +68,6 @@ static struct usb_driver cdc_ncm_driver;
 static int cdc_ncm_setup(struct usbnet *dev)
 {
 	struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
-	struct usb_cdc_ncm_ntb_parameters ncm_parm;
 	u32 val;
 	u8 flags;
 	u8 iface_no;
@@ -82,22 +81,22 @@ static int cdc_ncm_setup(struct usbnet *dev)
 	err = usbnet_read_cmd(dev, USB_CDC_GET_NTB_PARAMETERS,
 			      USB_TYPE_CLASS | USB_DIR_IN
 			      |USB_RECIP_INTERFACE,
-			      0, iface_no, &ncm_parm,
-			      sizeof(ncm_parm));
+			      0, iface_no, &ctx->ncm_parm,
+			      sizeof(ctx->ncm_parm));
 	if (err < 0) {
 		dev_err(&dev->intf->dev, "failed GET_NTB_PARAMETERS\n");
 		return err; /* GET_NTB_PARAMETERS is required */
 	}
 
 	/* read correct set of parameters according to device mode */
-	ctx->rx_max = le32_to_cpu(ncm_parm.dwNtbInMaxSize);
-	ctx->tx_max = le32_to_cpu(ncm_parm.dwNtbOutMaxSize);
-	ctx->tx_remainder = le16_to_cpu(ncm_parm.wNdpOutPayloadRemainder);
-	ctx->tx_modulus = le16_to_cpu(ncm_parm.wNdpOutDivisor);
-	ctx->tx_ndp_modulus = le16_to_cpu(ncm_parm.wNdpOutAlignment);
+	ctx->rx_max = le32_to_cpu(ctx->ncm_parm.dwNtbInMaxSize);
+	ctx->tx_max = le32_to_cpu(ctx->ncm_parm.dwNtbOutMaxSize);
+	ctx->tx_remainder = le16_to_cpu(ctx->ncm_parm.wNdpOutPayloadRemainder);
+	ctx->tx_modulus = le16_to_cpu(ctx->ncm_parm.wNdpOutDivisor);
+	ctx->tx_ndp_modulus = le16_to_cpu(ctx->ncm_parm.wNdpOutAlignment);
 	/* devices prior to NCM Errata shall set this field to zero */
-	ctx->tx_max_datagrams = le16_to_cpu(ncm_parm.wNtbOutMaxDatagrams);
-	ntb_fmt_supported = le16_to_cpu(ncm_parm.bmNtbFormatsSupported);
+	ctx->tx_max_datagrams = le16_to_cpu(ctx->ncm_parm.wNtbOutMaxDatagrams);
+	ntb_fmt_supported = le16_to_cpu(ctx->ncm_parm.bmNtbFormatsSupported);
 
 	/* there are some minor differences in NCM and MBIM defaults */
 	if (cdc_ncm_comm_intf_is_mbim(ctx->control->cur_altsetting)) {
@@ -146,7 +145,7 @@ static int cdc_ncm_setup(struct usbnet *dev)
 	}
 
 	/* inform device about NTB input size changes */
-	if (ctx->rx_max != le32_to_cpu(ncm_parm.dwNtbInMaxSize)) {
+	if (ctx->rx_max != le32_to_cpu(ctx->ncm_parm.dwNtbInMaxSize)) {
 		__le32 dwNtbInMaxSize = cpu_to_le32(ctx->rx_max);
 
 		err = usbnet_write_cmd(dev, USB_CDC_SET_NTB_INPUT_SIZE,
@@ -162,14 +161,6 @@ static int cdc_ncm_setup(struct usbnet *dev)
 		dev_dbg(&dev->intf->dev, "Using default maximum transmit length=%d\n",
 			CDC_NCM_NTB_MAX_SIZE_TX);
 		ctx->tx_max = CDC_NCM_NTB_MAX_SIZE_TX;
-
-		/* Adding a pad byte here simplifies the handling in
-		 * cdc_ncm_fill_tx_frame, by making tx_max always
-		 * represent the real skb max size.
-		 */
-		if (ctx->tx_max % usb_maxpacket(dev->udev, dev->out, 1) == 0)
-			ctx->tx_max++;
-
 	}
 
 	/*
@@ -439,6 +430,10 @@ int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, u8 data_
 		goto error2;
 	}
 
+	/* initialize data interface */
+	if (cdc_ncm_setup(dev))
+		goto error2;
+
 	/* configure data interface */
 	temp = usb_set_interface(dev->udev, iface_no, data_altsetting);
 	if (temp) {
@@ -453,12 +448,6 @@ int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, u8 data_
 		goto error2;
 	}
 
-	/* initialize data interface */
-	if (cdc_ncm_setup(dev))	{
-		dev_dbg(&intf->dev, "cdc_ncm_setup() failed\n");
-		goto error2;
-	}
-
 	usb_set_intfdata(ctx->data, dev);
 	usb_set_intfdata(ctx->control, dev);
 
@@ -475,6 +464,15 @@ int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, u8 data_
 	dev->hard_mtu = ctx->tx_max;
 	dev->rx_urb_size = ctx->rx_max;
 
+	/* cdc_ncm_setup will override dwNtbOutMaxSize if it is
+	 * outside the sane range. Adding a pad byte here if necessary
+	 * simplifies the handling in cdc_ncm_fill_tx_frame, making
+	 * tx_max always represent the real skb max size.
+	 */
+	if (ctx->tx_max != le32_to_cpu(ctx->ncm_parm.dwNtbOutMaxSize) &&
+	    ctx->tx_max % usb_maxpacket(dev->udev, dev->out, 1) == 0)
+		ctx->tx_max++;
+
 	return 0;
 
 error2:

include/linux/usb/cdc_ncm.h

@@ -88,6 +88,7 @@
 #define cdc_ncm_data_intf_is_mbim(x)  ((x)->desc.bInterfaceProtocol == USB_CDC_MBIM_PROTO_NTB)
 
 struct cdc_ncm_ctx {
+	struct usb_cdc_ncm_ntb_parameters ncm_parm;
 	struct hrtimer tx_timer;
 	struct tasklet_struct bh;