caif: Use link layer MTU instead of fixed MTU

Previously CAIF supported maximum transfer size of ~4050.
The transfer size is now calculated dynamically based on the
link layers mtu size.

Signed-off-by: Sjur Braendeland@stericsson.com
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 0 deletions

diff --git a/net/caif/cfdgml.c b/net/caif/cfdgml.c
index 32d9f0dc8463..ed9d53aff280 100644
--- a/net/caif/cfdgml.c
+++ b/net/caif/cfdgml.c
@@ -17,6 +17,7 @@
 #define DGM_FLOW_OFF 0x81
 #define DGM_FLOW_ON  0x80
 #define DGM_CTRL_PKT_SIZE 1
+#define DGM_MTU 1500
 
 static int cfdgml_receive(struct cflayer *layr, struct cfpkt *pkt);
 static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt);
@@ -89,6 +90,10 @@ static int cfdgml_transmit(struct cflayer *layr, struct cfpkt *pkt)
         if (!cfsrvl_ready(service, &ret))
                 return ret;
 
+        /* STE Modem cannot handle more than 1500 bytes datagrams */
+        if (cfpkt_getlen(pkt) > DGM_MTU)
+                return -EMSGSIZE;
+
         cfpkt_add_head(pkt, &zero, 4);
 
         /* Add info for MUX-layer to route the packet out. */