Message-ID: <694ab88ace7ed81faad706a248dc465d@apollo.open-resource.org>
Date:	Thu, 09 Jul 2015 13:11:51 +0000
From:	chrono <chrono@...n-resource.org>
To:	Enrico Mioso <mrkiko.rs@...il.com>
Cc:	openwrt-devel@...ts.openwrt.org,
	Matti Laakso <malaakso@...sanet.fi>,
	Oliver Neukum <oneukum@...e.com>, linux-usb@...r.kernel.org,
	netdev@...r.kernel.org
Subject: [PATCH V3] cdc_ncm: Add support for moving NDP to end of NCM frame

Ahoy everyone,

more on the Telekom Speedstick LTE V (Huawei 3372s) from here:

http://www.amazon.de/dp/B00NLJE3O6

I've tested Enricos latest patch on MIPS (3.18.17) and x86_64 (3.18.11)
and had a little bit of trouble applying it to latest trunk, so here's
the latest tested patch from a diff against 3.18.17 (openwrt-trunk).

With that patch applied, a simple AT^NDISDUP=1,1,"your.apn.here" and
udhcpc -i wwan0 is online and routing immediately.

The following config snippet is also working directly with openwrt:

config interface '4g'
         option proto 'ncm'
         option ifname 'wwan0'
         option device '/dev/ttyUSB1'
         option apn 'internet.eplus.de'

Again, big thanks go to Enrico for fixing NDP/SKB issues, much obliged.

-------------------------------------------------------------------------------
--- fix-huawei-3372s-ncm.patch ---

diff -u a/drivers/net/usb/cdc_mbim.c b/drivers/net/usb/cdc_mbim.c
--- a/drivers/net/usb/cdc_mbim.c	2015-06-28 17:40:40.000000000 +0000
+++ b/drivers/net/usb/cdc_mbim.c	2015-07-04 15:05:14.546901702 +0000
@@ -158,7 +158,7 @@
  	if (!cdc_ncm_comm_intf_is_mbim(intf->cur_altsetting))
  		goto err;

-	ret = cdc_ncm_bind_common(dev, intf, data_altsetting);
+	ret = cdc_ncm_bind_common(dev, intf, data_altsetting, 0);
  	if (ret)
  		goto err;

diff -u a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
--- a/drivers/net/usb/cdc_ncm.c	2015-06-28 17:40:40.000000000 +0000
+++ b/drivers/net/usb/cdc_ncm.c	2015-07-09 08:43:01.658770535 +0000
@@ -684,10 +684,11 @@
  		ctx->tx_curr_skb = NULL;
  	}

+	kfree(ctx->delayed_ndp16);
  	kfree(ctx);
  }

-int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, 
u8 data_altsetting)
+int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, 
u8 data_altsetting, int drvflags)
  {
  	const struct usb_cdc_union_desc *union_desc = NULL;
  	struct cdc_ncm_ctx *ctx;
@@ -855,6 +856,17 @@
  	/* finish setting up the device specific data */
  	cdc_ncm_setup(dev);

+	/* Device-specific flags */
+	ctx->drvflags = drvflags;
+
+	/* Allocate the delayed NDP if needed. */
+	if (ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END) {
+		ctx->delayed_ndp16 = kzalloc(ctx->max_ndp_size, GFP_KERNEL);
+		if (!ctx->delayed_ndp16)
+			goto error2;
+		dev_info(&intf->dev, "NDP will be placed at end of frame for this 
device.");
+	}
+
  	/* override ethtool_ops */
  	dev->net->ethtool_ops = &cdc_ncm_ethtool_ops;

@@ -954,8 +966,11 @@
  	if (cdc_ncm_select_altsetting(intf) != CDC_NCM_COMM_ALTSETTING_NCM)
  		return -ENODEV;

-	/* The NCM data altsetting is fixed */
-	ret = cdc_ncm_bind_common(dev, intf, CDC_NCM_DATA_ALTSETTING_NCM);
+	/* The NCM data altsetting is fixed, so we hard-coded it.
+	 * Additionally, generic NCM devices are assumed to accept arbitrarily
+	 * placed NDP.
+	 */
+	ret = cdc_ncm_bind_common(dev, intf, CDC_NCM_DATA_ALTSETTING_NCM, 0);

  	/*
  	 * We should get an event when network connection is "connected" or
@@ -986,6 +1001,14 @@
  	struct usb_cdc_ncm_nth16 *nth16 = (void *)skb->data;
  	size_t ndpoffset = le16_to_cpu(nth16->wNdpIndex);

+	/* If NDP should be moved to the end of the NCM package, we can't 
follow the
+	* NTH16 header as we would normally do. NDP isn't written to the SKB 
yet, and
+	* the wNdpIndex field in the header is actually not consistent with 
reality. It will be later.
+	*/
+	if (ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END)
+		if (ctx->delayed_ndp16->dwSignature == sign)
+			return ctx->delayed_ndp16;
+
  	/* follow the chain of NDPs, looking for a match */
  	while (ndpoffset) {
  		ndp16 = (struct usb_cdc_ncm_ndp16 *)(skb->data + ndpoffset);
@@ -995,7 +1018,8 @@
  	}

  	/* align new NDP */
-	cdc_ncm_align_tail(skb, ctx->tx_ndp_modulus, 0, ctx->tx_max);
+	if (!(ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END))
+		cdc_ncm_align_tail(skb, ctx->tx_ndp_modulus, 0, ctx->tx_max);

  	/* verify that there is room for the NDP and the datagram (reserve) */
  	if ((ctx->tx_max - skb->len - reserve) < ctx->max_ndp_size)
@@ -1008,7 +1032,11 @@
  		nth16->wNdpIndex = cpu_to_le16(skb->len);

  	/* push a new empty NDP */
-	ndp16 = (struct usb_cdc_ncm_ndp16 *)memset(skb_put(skb, 
ctx->max_ndp_size), 0, ctx->max_ndp_size);
+	if (!(ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END))
+		ndp16 = (struct usb_cdc_ncm_ndp16 *)memset(skb_put(skb, 
ctx->max_ndp_size), 0, ctx->max_ndp_size);
+	else
+		ndp16 = ctx->delayed_ndp16;
+
  	ndp16->dwSignature = sign;
  	ndp16->wLength = cpu_to_le16(sizeof(struct usb_cdc_ncm_ndp16) + 
sizeof(struct usb_cdc_ncm_dpe16));
  	return ndp16;
@@ -1023,6 +1051,15 @@
  	struct sk_buff *skb_out;
  	u16 n = 0, index, ndplen;
  	u8 ready2send = 0;
+	u32 delayed_ndp_size;
+
+	/* When our NDP gets written in cdc_ncm_ndp(), then skb_out->len gets 
updated
+	 * accordingly. Otherwise, we should check here.
+	 */
+	if (ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END)
+		delayed_ndp_size = ctx->max_ndp_size;
+	else
+		delayed_ndp_size = 0;

  	/* if there is a remaining skb, it gets priority */
  	if (skb != NULL) {
@@ -1077,7 +1114,7 @@
  		cdc_ncm_align_tail(skb_out,  ctx->tx_modulus, ctx->tx_remainder, 
ctx->tx_max);

  		/* check if we had enough room left for both NDP and frame */
-		if (!ndp16 || skb_out->len + skb->len > ctx->tx_max) {
+		if (!ndp16 || skb_out->len + skb->len + delayed_ndp_size > 
ctx->tx_max) {
  			if (n == 0) {
  				/* won't fit, MTU problem? */
  				dev_kfree_skb_any(skb);
@@ -1150,6 +1187,17 @@
  		/* variables will be reset at next call */
  	}

+	/* If requested, put NDP at end of frame. */
+	if (ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END) {
+		nth16 = (struct usb_cdc_ncm_nth16 *)skb_out->data;
+		cdc_ncm_align_tail(skb_out, ctx->tx_ndp_modulus, 0, ctx->tx_max);
+		nth16->wNdpIndex = cpu_to_le16(skb_out->len);
+		memcpy(skb_put(skb_out, ctx->max_ndp_size), ctx->delayed_ndp16, 
ctx->max_ndp_size);
+
+		/* Zero out delayed NDP - signature checking will naturally fail. */
+		ndp16 = memset(ctx->delayed_ndp16, 0, ctx->max_ndp_size);
+	}
+
  	/* If collected data size is less or equal ctx->min_tx_pkt
  	 * bytes, we send buffers as it is. If we get more data, it
  	 * would be more efficient for USB HS mobile device with DMA
diff -u a/drivers/net/usb/huawei_cdc_ncm.c 
b/drivers/net/usb/huawei_cdc_ncm.c
--- a/drivers/net/usb/huawei_cdc_ncm.c	2015-06-28 17:40:40.000000000 
+0000
+++ b/drivers/net/usb/huawei_cdc_ncm.c	2015-07-04 15:23:25.779014586 
+0000
@@ -73,11 +73,14 @@
  	struct usb_driver *subdriver = ERR_PTR(-ENODEV);
  	int ret = -ENODEV;
  	struct huawei_cdc_ncm_state *drvstate = (void *)&usbnet_dev->data;
+	int drvflags = 0;

  	/* altsetting should always be 1 for NCM devices - so we hard-coded
-	 * it here
+	 * it here. Some huawei devices will need the NDP part of the NCM 
package to
+	 * be at the end of the frame.
  	 */
-	ret = cdc_ncm_bind_common(usbnet_dev, intf, 1);
+	drvflags |= CDC_NCM_FLAG_NDP_TO_END;
+	ret = cdc_ncm_bind_common(usbnet_dev, intf, 1, drvflags);
  	if (ret)
  		goto err;

diff -u a/include/linux/usb/cdc_ncm.h b/include/linux/usb/cdc_ncm.h
--- a/include/linux/usb/cdc_ncm.h	2015-06-28 17:40:40.000000000 +0000
+++ b/include/linux/usb/cdc_ncm.h	2015-07-04 15:27:52.171388014 +0000
@@ -80,6 +80,9 @@
  #define CDC_NCM_TIMER_INTERVAL_MIN		5UL
  #define CDC_NCM_TIMER_INTERVAL_MAX		(U32_MAX / NSEC_PER_USEC)

+/* Driver flags */
+#define CDC_NCM_FLAG_NDP_TO_END			0x02	/* NDP is placed at end of frame 
*/
+
  #define cdc_ncm_comm_intf_is_mbim(x)  ((x)->desc.bInterfaceSubClass == 
USB_CDC_SUBCLASS_MBIM && \
  				       (x)->desc.bInterfaceProtocol == USB_CDC_PROTO_NONE)
  #define cdc_ncm_data_intf_is_mbim(x)  ((x)->desc.bInterfaceProtocol == 
USB_CDC_MBIM_PROTO_NTB)
@@ -103,9 +106,11 @@

  	spinlock_t mtx;
  	atomic_t stop;
+	int drvflags;

  	u32 timer_interval;
  	u32 max_ndp_size;
+	struct usb_cdc_ncm_ndp16 *delayed_ndp16;

  	u32 tx_timer_pending;
  	u32 tx_curr_frame_num;
@@ -133,7 +138,7 @@
  };

  u8 cdc_ncm_select_altsetting(struct usb_interface *intf);
-int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, 
u8 data_altsetting);
+int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, 
u8 data_altsetting, int drvflags);
  void cdc_ncm_unbind(struct usbnet *dev, struct usb_interface *intf);
  struct sk_buff *cdc_ncm_fill_tx_frame(struct usbnet *dev, struct 
sk_buff *skb, __le32 sign);
  int cdc_ncm_rx_verify_nth16(struct cdc_ncm_ctx *ctx, struct sk_buff 
*skb_in);

View attachment "fix-huawei-3372s-ncm.patch" of type "text/x-diff" (7439 bytes)

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