rtl8187: feedback transmitted packets using tx close descriptor for 8187B

Realtek 8187B has a receive command queue to feedback beacon interrupt
and transmitted packet status. Use it to feedback mac80211 about status
of transmitted packets. Unfortunately in the course of testing I found
that the sequence number reported by hardware includes entire sequence
control in a 12 bit only field, so a workaround is done to check only
lowest bits.

Tested-by: Larry Finger <Larry.Finger@lwfinger.net>
Tested-by: Hin-Tak Leung <htl10@users.sourceforge.net>
Signed-off-by: Herton Ronaldo Krzesinski <herton@mandriva.com.br>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 136 insertions, 4 deletions

diff --git a/drivers/net/wireless/rtl818x/rtl8187.h b/drivers/net/wireless/rtl818x/rtl8187.h
index f09872eec3d..c385407a994 100644
--- a/drivers/net/wireless/rtl818x/rtl8187.h
+++ b/drivers/net/wireless/rtl818x/rtl8187.h
@@ -113,6 +113,11 @@ struct rtl8187_priv {
         u8 noise;
         u8 slot_time;
         u8 aifsn[4];
+        struct {
+                __le64 buf;
+                struct urb *urb;
+                struct sk_buff_head queue;
+        } b_tx_status;
 };
 
 void rtl8187_write_phy(struct ieee80211_hw *dev, u8 addr, u32 data);
diff --git a/drivers/net/wireless/rtl818x/rtl8187_dev.c b/drivers/net/wireless/rtl818x/rtl8187_dev.c
index cb5bcefd1c3..876d4f93d31 100644
--- a/drivers/net/wireless/rtl818x/rtl8187_dev.c
+++ b/drivers/net/wireless/rtl818x/rtl8187_dev.c
@@ -176,8 +176,27 @@ static void rtl8187_tx_cb(struct urb *urb)
         skb_pull(skb, priv->is_rtl8187b ? sizeof(struct rtl8187b_tx_hdr) :
                                           sizeof(struct rtl8187_tx_hdr));
         ieee80211_tx_info_clear_status(info);
-        info->flags |= IEEE80211_TX_STAT_ACK;
-        ieee80211_tx_status_irqsafe(hw, skb);
+
+        if (!urb->status &&
+            !(info->flags & IEEE80211_TX_CTL_NO_ACK) &&
+            priv->is_rtl8187b) {
+                skb_queue_tail(&priv->b_tx_status.queue, skb);
+
+                /* queue is "full", discard last items */
+                while (skb_queue_len(&priv->b_tx_status.queue) > 5) {
+                        struct sk_buff *old_skb;
+
+                        dev_dbg(&priv->udev->dev,
+                                "transmit status queue full\n");
+
+                        old_skb = skb_dequeue(&priv->b_tx_status.queue);
+                        ieee80211_tx_status_irqsafe(hw, old_skb);
+                }
+        } else {
+                if (!(info->flags & IEEE80211_TX_CTL_NO_ACK) && !urb->status)
+                        info->flags |= IEEE80211_TX_STAT_ACK;
+                ieee80211_tx_status_irqsafe(hw, skb);
+        }
 }
 
 static int rtl8187_tx(struct ieee80211_hw *dev, struct sk_buff *skb)
@@ -219,7 +238,7 @@ static int rtl8187_tx(struct ieee80211_hw *dev, struct sk_buff *skb)
                 hdr->flags = cpu_to_le32(flags);
                 hdr->len = 0;
                 hdr->rts_duration = rts_dur;
-                hdr->retry = cpu_to_le32((info->control.rates[0].count - 1) << 8);
+                hdr->retry = cpu_to_le32(info->control.rates[0].count << 8);
                 buf = hdr;
 
                 ep = 2;
@@ -237,7 +256,7 @@ static int rtl8187_tx(struct ieee80211_hw *dev, struct sk_buff *skb)
                 memset(hdr, 0, sizeof(*hdr));
                 hdr->flags = cpu_to_le32(flags);
                 hdr->rts_duration = rts_dur;
-                hdr->retry = cpu_to_le32((info->control.rates[0].count - 1) << 8);
+                hdr->retry = cpu_to_le32(info->control.rates[0].count << 8);
                 hdr->tx_duration =
                         ieee80211_generic_frame_duration(dev, priv->vif,
                                                          skb->len, txrate);
@@ -403,6 +422,109 @@ static int rtl8187_init_urbs(struct ieee80211_hw *dev)
         return 0;
 }
 
+static void rtl8187b_status_cb(struct urb *urb)
+{
+        struct ieee80211_hw *hw = (struct ieee80211_hw *)urb->context;
+        struct rtl8187_priv *priv = hw->priv;
+        u64 val;
+        unsigned int cmd_type;
+
+        if (unlikely(urb->status)) {
+                usb_free_urb(urb);
+                return;
+        }
+
+        /*
+         * Read from status buffer:
+         *
+         * bits [30:31] = cmd type:
+         * - 0 indicates tx beacon interrupt
+         * - 1 indicates tx close descriptor
+         *
+         * In the case of tx beacon interrupt:
+         * [0:9] = Last Beacon CW
+         * [10:29] = reserved
+         * [30:31] = 00b
+         * [32:63] = Last Beacon TSF
+         *
+         * If it's tx close descriptor:
+         * [0:7] = Packet Retry Count
+         * [8:14] = RTS Retry Count
+         * [15] = TOK
+         * [16:27] = Sequence No
+         * [28] = LS
+         * [29] = FS
+         * [30:31] = 01b
+         * [32:47] = unused (reserved?)
+         * [48:63] = MAC Used Time
+         */
+        val = le64_to_cpu(priv->b_tx_status.buf);
+
+        cmd_type = (val >> 30) & 0x3;
+        if (cmd_type == 1) {
+                unsigned int pkt_rc, seq_no;
+                bool tok;
+                struct sk_buff *skb;
+                struct ieee80211_hdr *ieee80211hdr;
+                unsigned long flags;
+
+                pkt_rc = val & 0xFF;
+                tok = val & (1 << 15);
+                seq_no = (val >> 16) & 0xFFF;
+
+                spin_lock_irqsave(&priv->b_tx_status.queue.lock, flags);
+                skb_queue_reverse_walk(&priv->b_tx_status.queue, skb) {
+                        ieee80211hdr = (struct ieee80211_hdr *)skb->data;
+
+                        /*
+                         * While testing, it was discovered that the seq_no
+                         * doesn't actually contains the sequence number.
+                         * Instead of returning just the 12 bits of sequence
+                         * number, hardware is returning entire sequence control
+                         * (fragment number plus sequence number) in a 12 bit
+                         * only field overflowing after some time. As a
+                         * workaround, just consider the lower bits, and expect
+                         * it's unlikely we wrongly ack some sent data
+                         */
+                        if ((le16_to_cpu(ieee80211hdr->seq_ctrl)
+                            & 0xFFF) == seq_no)
+                                break;
+                }
+                if (skb != (struct sk_buff *) &priv->b_tx_status.queue) {
+                        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+
+                        __skb_unlink(skb, &priv->b_tx_status.queue);
+                        if (tok)
+                                info->flags |= IEEE80211_TX_STAT_ACK;
+                        info->status.rates[0].count = pkt_rc;
+
+                        ieee80211_tx_status_irqsafe(hw, skb);
+                }
+                spin_unlock_irqrestore(&priv->b_tx_status.queue.lock, flags);
+        }
+
+        usb_submit_urb(urb, GFP_ATOMIC);
+}
+
+static int rtl8187b_init_status_urb(struct ieee80211_hw *dev)
+{
+        struct rtl8187_priv *priv = dev->priv;
+        struct urb *entry;
+
+        entry = usb_alloc_urb(0, GFP_KERNEL);
+        if (!entry)
+                return -ENOMEM;
+        priv->b_tx_status.urb = entry;
+
+        usb_fill_bulk_urb(entry, priv->udev, usb_rcvbulkpipe(priv->udev, 9),
+                          &priv->b_tx_status.buf, sizeof(priv->b_tx_status.buf),
+                          rtl8187b_status_cb, dev);
+
+        usb_submit_urb(entry, GFP_KERNEL);
+
+        return 0;
+}
+
 static int rtl8187_cmd_reset(struct ieee80211_hw *dev)
 {
         struct rtl8187_priv *priv = dev->priv;
@@ -755,6 +877,7 @@ static int rtl8187_start(struct ieee80211_hw *dev)
                                   (7 << 0  /* long retry limit */) |
                                   (7 << 21 /* MAX TX DMA */));
                 rtl8187_init_urbs(dev);
+                rtl8187b_init_status_urb(dev);
                 mutex_unlock(&priv->conf_mutex);
                 return 0;
         }
@@ -831,6 +954,9 @@ static void rtl8187_stop(struct ieee80211_hw *dev)
                 usb_kill_urb(info->urb);
                 kfree_skb(skb);
         }
+        while ((skb = skb_dequeue(&priv->b_tx_status.queue)))
+                dev_kfree_skb_any(skb);
+        usb_kill_urb(priv->b_tx_status.urb);
         mutex_unlock(&priv->conf_mutex);
 }
 
@@ -1317,6 +1443,7 @@ static int __devinit rtl8187_probe(struct usb_interface *intf,
                 goto err_free_dev;
         }
         mutex_init(&priv->conf_mutex);
+        skb_queue_head_init(&priv->b_tx_status.queue);
 
         printk(KERN_INFO "%s: hwaddr %pM, %s V%d + %s\n",
                wiphy_name(dev->wiphy), dev->wiphy->perm_addr,