zd1211rw: Fix TX status reporting in order to have proper rate control

First, we reduce the number of hardware retries to 0 (ie 2 real retries
for each rate). Next, when we report the retries to mac80211, we always
report a retry count of 1 (it seems to be 2 in fact, but using 2 seems
to lead to wrong performance for some reason). We use a state machine to
determine the real fate of a packet based on the 802.11 ACK and what the
Zydas hardware is saying when a real retry occurs. The real retry rates
are encoded in a static array. It has been tested with both zd1211 and
zd1211b hardware. Of course, since the Zydas hardware is not reporting
retries accurately, we are just doing our best in order to get the best
performance (ie higher throughput).

Signed-off-by: Benoit PAPILLAULT <benoit.papillault@free.fr>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 23 insertions, 2 deletions

diff --git a/drivers/net/wireless/zd1211rw/zd_mac.h b/drivers/net/wireless/zd1211rw/zd_mac.h
index 7c2759118d13..630c298a730e 100644
--- a/drivers/net/wireless/zd1211rw/zd_mac.h
+++ b/drivers/net/wireless/zd1211rw/zd_mac.h
@@ -140,6 +140,21 @@ struct rx_status {
 #define ZD_RX_CRC16_ERROR		0x40
 #define ZD_RX_ERROR			0x80
 
+struct tx_retry_rate {
+	int count;	/* number of valid element in rate[] array */
+	int rate[10];	/* retry rates, described by an index in zd_rates[] */
+};
+
+struct tx_status {
+	u8 type;	/* must always be 0x01 : USB_INT_TYPE */
+	u8 id;		/* must always be 0xa0 : USB_INT_ID_RETRY_FAILED */
+	u8 rate;
+	u8 pad;
+	u8 mac[ETH_ALEN];
+	u8 retry;
+	u8 failure;
+} __attribute__((packed));
+
 enum mac_flags {
 	MAC_FIXED_CHANNEL = 0x01,
 };
@@ -150,7 +165,7 @@ struct housekeeping {
 
 #define ZD_MAC_STATS_BUFFER_SIZE 16
 
-#define ZD_MAC_MAX_ACK_WAITERS 10
+#define ZD_MAC_MAX_ACK_WAITERS 50
 
 struct zd_mac {
 	struct zd_chip chip;
@@ -184,6 +199,12 @@ struct zd_mac {
 
 	/* whether to pass control frames to stack */
 	unsigned int pass_ctrl:1;
+
+	/* whether we have received a 802.11 ACK that is pending */
+	unsigned int ack_pending:1;
+
+	/* signal strength of the last 802.11 ACK received */
+	int ack_signal;
 };
 
 #define ZD_REGDOMAIN_FCC	0x10
@@ -279,7 +300,7 @@ int zd_mac_preinit_hw(struct ieee80211_hw *hw);
 int zd_mac_init_hw(struct ieee80211_hw *hw);
 
 int zd_mac_rx(struct ieee80211_hw *hw, const u8 *buffer, unsigned int length);
-void zd_mac_tx_failed(struct ieee80211_hw *hw);
+void zd_mac_tx_failed(struct urb *urb);
 void zd_mac_tx_to_dev(struct sk_buff *skb, int error);
 
 #ifdef DEBUG