[PATCH] cdc_ncm: fix short packet issue on some devices

From: Greg KH
Date: Sun Apr 24 2011 - 20:02:51 EST


From: Hans Petter Selasky <hselasky@xxxxxxx>

The default maximum transmit length for NCM USB frames should be so
that a short packet happens at the end if the device supports a length
greater than the defined maximum. This is achieved by adding 4 bytes
to the maximum length so that the existing logic can fit a short
packet there.

Signed-off-by: Hans Petter Selasky <hselasky@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
drivers/net/usb/cdc_ncm.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 967371f..1033ef6 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -54,13 +54,13 @@
#include <linux/usb/usbnet.h>
#include <linux/usb/cdc.h>

-#define DRIVER_VERSION "7-Feb-2011"
+#define DRIVER_VERSION "23-Apr-2011"

/* CDC NCM subclass 3.2.1 */
#define USB_CDC_NCM_NDP16_LENGTH_MIN 0x10

/* Maximum NTB length */
-#define CDC_NCM_NTB_MAX_SIZE_TX 16384 /* bytes */
+#define CDC_NCM_NTB_MAX_SIZE_TX (16384 + 4) /* bytes, must be short terminated */
#define CDC_NCM_NTB_MAX_SIZE_RX 16384 /* bytes */

/* Minimum value for MaxDatagramSize, ch. 6.2.9 */
--
1.7.1.1

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