[PATCH 2/2] b43: fix tx status reporting on rate fallback

[Felix Fietkau <nbd@openwrt.org>]

If the hardware uses RTS/CTS reporting and the actual RTS/CTS
handshake failed, it will switch to the fallback rate, even
though the main rate was never actually attempted.
Make sure that this does not screw up rate control statistics.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

--- a/drivers/net/wireless/b43/b43.h
+++ b/drivers/net/wireless/b43/b43.h
@@ -778,6 +778,9 @@ struct b43_wldev {
 #ifdef CONFIG_B43_DEBUG
 	struct b43_dfsentry *dfsentry;
 #endif
+
+	/* necessary for figuring out the correct tx status */
+	int short_retry;
 };
 
 static inline struct b43_wl *hw_to_b43_wl(struct ieee80211_hw *hw)
--- a/drivers/net/wireless/b43/dma.c
+++ b/drivers/net/wireless/b43/dma.c
@@ -1393,7 +1393,7 @@ void b43_dma_handle_txstatus(struct b43_
 			 * Call back to inform the ieee80211 subsystem about
 			 * the status of the transmission.
 			 */
-			frame_succeed = b43_fill_txstatus_report(info, status);
+			frame_succeed = b43_fill_txstatus_report(dev, info, status);
 #ifdef CONFIG_B43_DEBUG
 			if (frame_succeed)
 				ring->nr_succeed_tx_packets++;
--- a/drivers/net/wireless/b43/main.c
+++ b/drivers/net/wireless/b43/main.c
@@ -3892,6 +3892,7 @@ static void b43_set_retry_limits(struct 
 			short_retry);
 	b43_shm_write16(dev, B43_SHM_SCRATCH, B43_SHM_SC_LRLIMIT,
 			long_retry);
+	dev->short_retry = short_retry;
 }
 
 static void b43_set_synth_pu_delay(struct b43_wldev *dev, bool idle)
--- a/drivers/net/wireless/b43/pio.c
+++ b/drivers/net/wireless/b43/pio.c
@@ -589,7 +589,7 @@ void b43_pio_handle_txstatus(struct b43_
 	info = IEEE80211_SKB_CB(pack->skb);
 	memset(&info->status, 0, sizeof(info->status));
 
-	b43_fill_txstatus_report(info, status);
+	b43_fill_txstatus_report(dev, info, status);
 
 	total_len = pack->skb->len + b43_txhdr_size(dev);
 	total_len = roundup(total_len, 4);
--- a/drivers/net/wireless/b43/xmit.c
+++ b/drivers/net/wireless/b43/xmit.c
@@ -687,7 +687,8 @@ void b43_handle_txstatus(struct b43_wlde
 /* Fill out the mac80211 TXstatus report based on the b43-specific
  * txstatus report data. This returns a boolean whether the frame was
  * successfully transmitted. */
-bool b43_fill_txstatus_report(struct ieee80211_tx_info *report,
+bool b43_fill_txstatus_report(struct b43_wldev *dev,
+			      struct ieee80211_tx_info *report,
 			      const struct b43_txstatus *status)
 {
 	bool frame_success = 1;
@@ -706,8 +707,19 @@ bool b43_fill_txstatus_report(struct iee
 	if (status->frame_count == 0) {
 		/* The frame was not transmitted at all. */
 		report->status.retry_count = 0;
-	} else
+	} else if (status->rts_count > dev->short_retry) {
+		/*
+		 * If the short retries (RTS, not data frame) have exceeded
+		 * the limit, the hw will not have tried the selected rate,
+		 * but will have used the fallback rate instead.
+		 * Don't let the rate control count attempts for the selected
+		 * rate in this case, otherwise the statistics will be off.
+		 */
+		report->tx_rate_idx = 0;
+		report->status.retry_count = 0;
+	} else {
 		report->status.retry_count = status->frame_count - 1;
+	}
 
 	return frame_success;
 }
--- a/drivers/net/wireless/b43/xmit.h
+++ b/drivers/net/wireless/b43/xmit.h
@@ -294,7 +294,8 @@ void b43_rx(struct b43_wldev *dev, struc
 
 void b43_handle_txstatus(struct b43_wldev *dev,
 			 const struct b43_txstatus *status);
-bool b43_fill_txstatus_report(struct ieee80211_tx_info *report,
+bool b43_fill_txstatus_report(struct b43_wldev *dev,
+			      struct ieee80211_tx_info *report,
 			      const struct b43_txstatus *status);
 
 void b43_tx_suspend(struct b43_wldev *dev);