In order to mitigate the problem of having no internet at all, we got a SIM-Card for LTE/4Ǵ. At the same time the Telekom Speedstick V LTE (which is basically a rebranded Huawei 3372s) became available and not too expensive. A little research showed that it should be really easy to deploy this stick, when flashing a Non-HiLink Firmware (⇐21.xxx), when the Stick could be used just like old modems, with at commands but without the dependency to run pppd/wvdial like in the old modem or even 3G days. You just have to
$ echo "AT^NDISDUP=1,1,"internet.eplus.de" > /dev/ttyUSB1 $ udhcpc wwan0
and should be done with it. In reality this became quite a quest but with combined efforts we managed to get it to work and created a patch for current kernels (tested 3.18.[11-18]. If you also have this stick and are unable to get an IP via dhcp, this patch might be for you.
$ make clean
$ make target/linux/{clean,prepare} V=s QUILT=1
$ cd build_dir/target-mips_34kc_musl-1.1.10/linux-ar71xx_generic/linux-3.18.18/
$ patch -p1 -i /path/to/patchfile/fix-cdc-ncm-huawei-3372s.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);