Subject: Re: Is this 32-bit NCM?

From: Bjørn Mork <[email-masked]>
Date: Tue, 02 Dec 2014 12:21:18 +0100

Enrico Mioso <[email-masked]> writes:

> Kevin - it works! the key seems to be in the tx_fixup function; there is a 
> special handling for frames effectively.
> Please ... help me backport those changes to the standard Linux driver - it 
> will be a gain for us all, and in general you'll have a more probable 
> maintenance than you would with the driver from huawei.

Very interesting.  The NCM code in the huawei driver has a different
origin, so it is quite different and not too easy to merge into the
existing Linux cdc_ncm driver.

But this does pinpoint differences we should explore.  One is the
placement of the NDP: The Huawei driver puts it at the end.  Another,
which is much easier to test out quickly, is the sequence numbering: The
Huawei driver doesn't use it.

So I wonder if this makes any difference:

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 80a844e0ae03..37f11770acb6 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -1049,7 +1049,7 @@ cdc_ncm_fill_tx_frame(struct usbnet *dev, struct sk_buff *skb, __le32 sign)
 		nth16 = (struct usb_cdc_ncm_nth16 *)memset(skb_put(skb_out, sizeof(struct usb_cdc_ncm_nth16)), 0, sizeof(struct usb_cdc_ncm_nth16));
 		nth16->dwSignature = cpu_to_le32(USB_CDC_NCM_NTH16_SIGN);
 		nth16->wHeaderLength = cpu_to_le16(sizeof(struct usb_cdc_ncm_nth16));
-		nth16->wSequence = cpu_to_le16(ctx->tx_seq++);
+//		nth16->wSequence = cpu_to_le16(ctx->tx_seq++);
 
 		/* count total number of frames in this NTB */
 		ctx->tx_curr_frame_num = 0;

Bjørn