cdc_ncm: fix MTU and max_datagram_size handling

Changes/fixes:
- inform device if max_datagram_size was changed by host
- max_datagram_size can't be bigger MTU in ETH func descr
- fix constants definitions to enable running CAIF service over NCM

Tested on Intel/ARM.

Reviewed-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Tested-by: Dmitry Tarnyagin <Dmitry.Tarnyagin@stericsson.com>
Signed-off-by: Alexey Orishko <alexey.orishko@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 18 deletions

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index a8e2a62c2958..f8f194658412 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -58,8 +58,8 @@
 #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_RX                 16384   /* bytes */
+#define CDC_NCM_NTB_MAX_SIZE_TX                 32768   /* bytes */
+#define CDC_NCM_NTB_MAX_SIZE_RX                 32768   /* bytes */
 
 /* Minimum value for MaxDatagramSize, ch. 6.2.9 */
 #define CDC_NCM_MIN_DATAGRAM_SIZE               1514    /* bytes */
@@ -67,13 +67,13 @@
 #define CDC_NCM_MIN_TX_PKT                      512     /* bytes */
 
 /* Default value for MaxDatagramSize */
-#define CDC_NCM_MAX_DATAGRAM_SIZE               2048    /* bytes */
+#define CDC_NCM_MAX_DATAGRAM_SIZE               8192    /* bytes */
 
 /*
  * Maximum amount of datagrams in NCM Datagram Pointer Table, not counting
  * the last NULL entry. Any additional datagrams in NTB would be discarded.
  */
-#define CDC_NCM_DPT_DATAGRAMS_MAX               32
+#define CDC_NCM_DPT_DATAGRAMS_MAX               40
 
 /* Maximum amount of IN datagrams in NTB */
 #define CDC_NCM_DPT_DATAGRAMS_IN_MAX            0 /* unlimited */
@@ -366,27 +366,25 @@ size_err:
                 if (err < 0) {
                         pr_debug("GET_MAX_DATAGRAM_SIZE failed, use size=%u\n",
                                                 CDC_NCM_MIN_DATAGRAM_SIZE);
-                        kfree(max_datagram_size);
                 } else {
                         ctx->max_datagram_size =
                                 le16_to_cpu(*max_datagram_size);
                         /* Check Eth descriptor value */
-                        if (eth_max_sz < CDC_NCM_MAX_DATAGRAM_SIZE) {
-                                if (ctx->max_datagram_size > eth_max_sz)
+                        if (ctx->max_datagram_size > eth_max_sz)
                                         ctx->max_datagram_size = eth_max_sz;
-                        } else {
-                                if (ctx->max_datagram_size >
-                                                CDC_NCM_MAX_DATAGRAM_SIZE)
-                                        ctx->max_datagram_size =
+
+                        if (ctx->max_datagram_size > CDC_NCM_MAX_DATAGRAM_SIZE)
+                                ctx->max_datagram_size =
                                                 CDC_NCM_MAX_DATAGRAM_SIZE;
-                        }
 
                         if (ctx->max_datagram_size < CDC_NCM_MIN_DATAGRAM_SIZE)
                                 ctx->max_datagram_size =
                                         CDC_NCM_MIN_DATAGRAM_SIZE;
 
                         /* if value changed, update device */
-                        err = usb_control_msg(ctx->udev,
+                        if (ctx->max_datagram_size !=
+                                        le16_to_cpu(*max_datagram_size)) {
+                                err = usb_control_msg(ctx->udev,
                                                 usb_sndctrlpipe(ctx->udev, 0),
                                                 USB_CDC_SET_MAX_DATAGRAM_SIZE,
                                                 USB_TYPE_CLASS | USB_DIR_OUT
@@ -394,14 +392,14 @@ size_err:
                                                 0,
                                                 iface_no, max_datagram_size,
                                                 2, 1000);
-                        kfree(max_datagram_size);
-max_dgram_err:
-                        if (err < 0)
-                                pr_debug("SET_MAX_DATAGRAM_SIZE failed\n");
+                                if (err < 0)
+                                        pr_debug("SET_MAX_DGRAM_SIZE failed\n");
+                        }
                 }
-
+                kfree(max_datagram_size);
         }
 
+max_dgram_err:
         if (ctx->netdev->mtu != (ctx->max_datagram_size - ETH_HLEN))
                 ctx->netdev->mtu = ctx->max_datagram_size - ETH_HLEN;