mac802154: correct max sifs size handling

This patch fix the max sifs size correction when the
IEEE802154_HW_TX_OMIT_CKSUM flag is set. With this flag the sk_buff
doesn't contain the CRC, because the transceiver will add the CRC
while transmit.

Also add some defines for the max sifs frame size value and frame check
sequence according to 802.15.4 standard.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

diff --git a/include/linux/ieee802154.h b/include/linux/ieee802154.h
index 40b0ab9..8872ca1 100644 (file)
--- a/include/linux/ieee802154.h
+++ b/include/linux/ieee802154.h
@@ -30,6 +30,7 @@
 #define IEEE802154_MTU                 127
 #define IEEE802154_ACK_PSDU_LEN                5
 #define IEEE802154_MIN_PSDU_LEN                9
+#define IEEE802154_FCS_LEN             2
 
 #define IEEE802154_PAN_ID_BROADCAST    0xffff
 #define IEEE802154_ADDR_SHORT_BROADCAST        0xffff
@@ -39,6 +40,7 @@
 
 #define IEEE802154_LIFS_PERIOD         40
 #define IEEE802154_SIFS_PERIOD         12
+#define IEEE802154_MAX_SIFS_FRAME_SIZE 18
 
 #define IEEE802154_MAX_CHANNEL         26
 #define IEEE802154_MAX_PAGE            31

diff --git a/net/mac802154/util.c b/net/mac802154/util.c
index 5fc9790..150bf80 100644 (file)
--- a/net/mac802154/util.c
+++ b/net/mac802154/util.c
@@ -65,8 +65,19 @@ void ieee802154_xmit_complete(struct ieee802154_hw *hw, struct sk_buff *skb,
 {
        if (ifs_handling) {
                struct ieee802154_local *local = hw_to_local(hw);
+               u8 max_sifs_size;
 
-               if (skb->len > 18)
+               /* If transceiver sets CRC on his own we need to use lifs
+                * threshold len above 16 otherwise 18, because it's not
+                * part of skb->len.
+                */
+               if (hw->flags & IEEE802154_HW_TX_OMIT_CKSUM)
+                       max_sifs_size = IEEE802154_MAX_SIFS_FRAME_SIZE -
+                                       IEEE802154_FCS_LEN;
+               else
+                       max_sifs_size = IEEE802154_MAX_SIFS_FRAME_SIZE;
+
+               if (skb->len > max_sifs_size)
                        hrtimer_start(&local->ifs_timer,
                                      ktime_set(0, hw->phy->lifs_period * NSEC_PER_USEC),
                                      HRTIMER_MODE_REL);