rt2x00: Improve TX status entry validation

The TX_STA_FIFO contains some information for identifying
a outgoing frame, however matching by WCID and ACK status is
not sufficient to 100% identify the macthing queue_entry structure
(containing the SKB buffer) which belongs to the status report.

Within TX_STA_FIFO we have a 4-bit field named PACKETID, which is
currently used to encode the queue id. The queue ID is however
limited to values from 0 to 3, which means 2 bits are sufficient
to encode the value. With the remaining 2 bits we can encode a
partial queue_entry index number. The value of PACKETID is not
allowed to become 0, with the queue ID ranging from 0 to 3, at least
one of the bits for the entry identification must be 1.

That leaves us with 3 possible values we can still encode in the
bits. Altough this doesn't allow 100% accurate matching of the
TX_STA_FIFO queue to a queue_entry structure, it at least improves
the accuracy. This allows us to better detect if we have missed the
TX_STA_FIFO report, which in turn reduces the number of watchdog
warnings regarding the TX status timeout.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 13 insertions, 1 deletions

diff --git a/drivers/net/wireless/rt2x00/rt2800.h b/drivers/net/wireless/rt2x00/rt2800.h
index 4930d29e1377..2a9f4020af1e 100644
--- a/drivers/net/wireless/rt2x00/rt2800.h
+++ b/drivers/net/wireless/rt2x00/rt2800.h
@@ -1,5 +1,6 @@
 /*
-        Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com>
+        Copyright (C) 2004 - 2010 Ivo van Doorn <IvDoorn@gmail.com>
+        Copyright (C) 2010 Willow Garage <http://www.willowgarage.com>
         Copyright (C) 2009 Alban Browaeys <prahal@yahoo.com>
         Copyright (C) 2009 Felix Fietkau <nbd@openwrt.org>
         Copyright (C) 2009 Luis Correia <luis.f.correia@gmail.com>
@@ -1353,6 +1354,9 @@
  * PID_TYPE: The PID latched from the PID field in the TXWI, can be used
  *           to match a frame with its tx result (even though the PID is
  *           only 4 bits wide).
+ * PID_QUEUE: Part of PID_TYPE, this is the queue index number (0-3)
+ * PID_ENTRY: Part of PID_TYPE, this is the queue entry index number (1-3)
+ *            This identification number is calculated by ((idx % 3) + 1).
  * TX_SUCCESS: Indicates tx success (1) or failure (0)
  * TX_AGGRE: Indicates if the frame was part of an aggregate (1) or not (0)
  * TX_ACK_REQUIRED: Indicates if the frame needed to get ack'ed (1) or not (0)
@@ -1364,6 +1368,8 @@
 #define TX_STA_FIFO                     0x1718
 #define TX_STA_FIFO_VALID               FIELD32(0x00000001)
 #define TX_STA_FIFO_PID_TYPE            FIELD32(0x0000001e)
+#define TX_STA_FIFO_PID_QUEUE           FIELD32(0x00000006)
+#define TX_STA_FIFO_PID_ENTRY           FIELD32(0x00000018)
 #define TX_STA_FIFO_TX_SUCCESS          FIELD32(0x00000020)
 #define TX_STA_FIFO_TX_AGGRE            FIELD32(0x00000040)
 #define TX_STA_FIFO_TX_ACK_REQUIRED     FIELD32(0x00000080)
@@ -2024,6 +2030,10 @@ struct mac_iveiv_entry {
  *           frame was processed. If multiple frames are aggregated together
  *           (AMPDU==1) the reported tx status will always contain the packet
  *           id of the first frame. 0: Don't report tx status for this frame.
+ * PACKETID_QUEUE: Part of PACKETID, This is the queue index (0-3)
+ * PACKETID_ENTRY: Part of PACKETID, THis is the queue entry index (1-3)
+ *                 This identification number is calculated by ((idx % 3) + 1).
+ *                 The (+1) is required to prevent PACKETID to become 0.
  */
 #define TXWI_W1_ACK                     FIELD32(0x00000001)
 #define TXWI_W1_NSEQ                    FIELD32(0x00000002)
@@ -2031,6 +2041,8 @@ struct mac_iveiv_entry {
 #define TXWI_W1_WIRELESS_CLI_ID         FIELD32(0x0000ff00)
 #define TXWI_W1_MPDU_TOTAL_BYTE_COUNT   FIELD32(0x0fff0000)
 #define TXWI_W1_PACKETID                FIELD32(0xf0000000)
+#define TXWI_W1_PACKETID_QUEUE          FIELD32(0x30000000)
+#define TXWI_W1_PACKETID_ENTRY          FIELD32(0xc0000000)
 
 /*
  * Word2