p54: implement MRR

This implements multi-rate retry in p54. With lots of help
and testing from Christian and the limiting idea from nbd.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: Christian Lamparter <chunkeey@web.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/p54/p54common.c b/drivers/net/wireless/p54/p54common.c
index 65be5eca23404c65d265c11c7ba64de091ccbbbf..237090140243ccb54b778867107af6bbbbd16588 100644 (file)
--- a/drivers/net/wireless/p54/p54common.c
+++ b/drivers/net/wireless/p54/p54common.c
@@ -1,9 +1,9 @@
-
 /*
  * Common code for mac80211 Prism54 drivers
  *
  * Copyright (c) 2006, Michael Wu <flamingice@sourmilk.net>
  * Copyright (c) 2007, Christian Lamparter <chunkeey@web.de>
+ * Copyright 2008, Johannes Berg <johannes@sipsolutions.net>
  *
  * Based on the islsm (softmac prism54) driver, which is:
  * Copyright 2004-2006 Jean-Baptiste Note <jbnote@gmail.com>, et al.
@@ -544,6 +544,7 @@ static void p54_rx_frame_sent(struct ieee80211_hw *dev, struct sk_buff *skb)
        u32 freed = 0;
        u32 last_addr = priv->rx_start;
        unsigned long flags;
+       int count, idx;
 
        spin_lock_irqsave(&priv->tx_queue.lock, flags);
        while (entry != (struct sk_buff *)&priv->tx_queue) {
@@ -568,18 +569,39 @@ static void p54_rx_frame_sent(struct ieee80211_hw *dev, struct sk_buff *skb)
                        __skb_unlink(entry, &priv->tx_queue);
                        spin_unlock_irqrestore(&priv->tx_queue.lock, flags);
 
-                       ieee80211_tx_info_clear_status(info);
+                       /*
+                        * Clear manually, ieee80211_tx_info_clear_status would
+                        * clear the counts too and we need them.
+                        */
+                       memset(&info->status.ampdu_ack_len, 0,
+                              sizeof(struct ieee80211_tx_info) -
+                              offsetof(struct ieee80211_tx_info, status.ampdu_ack_len));
+                       BUILD_BUG_ON(offsetof(struct ieee80211_tx_info,
+                                             status.ampdu_ack_len) != 23);
+
                        entry_hdr = (struct p54_control_hdr *) entry->data;
                        entry_data = (struct p54_tx_control_allocdata *) entry_hdr->data;
                        if ((entry_hdr->magic1 & cpu_to_le16(0x4000)) != 0)
                                pad = entry_data->align[0];
 
-                       priv->tx_stats[entry_data->hw_queue].len--;
-                       if (!(info->flags & IEEE80211_TX_CTL_NO_ACK)) {
-                               if (!(payload->status & 0x01))
-                                       info->flags |= IEEE80211_TX_STAT_ACK;
+                       /* walk through the rates array and adjust the counts */
+                       count = payload->retries;
+                       for (idx = 0; idx < 4; idx++) {
+                               if (count >= info->status.rates[idx].count) {
+                                       count -= info->status.rates[idx].count;
+                               } else if (count > 0) {
+                                       info->status.rates[idx].count = count;
+                                       count = 0;
+                               } else {
+                                       info->status.rates[idx].idx = -1;
+                                       info->status.rates[idx].count = 0;
+                               }
                        }
-                       info->status.rates[0].count = payload->retries;
+
+                       priv->tx_stats[entry_data->hw_queue].len--;
+                       if (!(info->flags & IEEE80211_TX_CTL_NO_ACK) &&
+                           !(payload->status & 0x01))
+                               info->flags |= IEEE80211_TX_STAT_ACK;
                        info->status.ack_signal = p54_rssi_to_dbm(dev,
                                        le16_to_cpu(payload->ack_rssi));
                        skb_pull(entry, sizeof(*hdr) + pad + sizeof(*entry_data));
@@ -802,9 +824,12 @@ static int p54_tx(struct ieee80211_hw *dev, struct sk_buff *skb)
        struct p54_control_hdr *hdr;
        struct p54_tx_control_allocdata *txhdr;
        size_t padding, len;
+       int i, j, ridx;
        u8 rate;
        u8 cts_rate = 0x20;
        u8 rc_flags;
+       u8 calculated_tries[4];
+       u8 nrates = 0, nremaining = 8;
 
        current_queue = &priv->tx_stats[skb_get_queue_mapping(skb) + 4];
        if (unlikely(current_queue->len > current_queue->limit))
@@ -827,23 +852,74 @@ static int p54_tx(struct ieee80211_hw *dev, struct sk_buff *skb)
                hdr->magic1 = cpu_to_le16(0x0010);
        hdr->len = cpu_to_le16(len);
        hdr->type = (info->flags & IEEE80211_TX_CTL_NO_ACK) ? 0 : cpu_to_le16(1);
-       hdr->retry1 = hdr->retry2 = info->control.rates[0].count;
-
-       /* TODO: add support for alternate retry TX rates */
-       rate = ieee80211_get_tx_rate(dev, info)->hw_value;
-       rc_flags = info->control.rates[0].flags;
-       if (rc_flags & IEEE80211_TX_RC_USE_SHORT_PREAMBLE) {
-               rate |= 0x10;
-               cts_rate |= 0x10;
+       hdr->retry1 = info->control.rates[0].count;
+
+       /*
+        * we register the rates in perfect order, and
+        * RTS/CTS won't happen on 5 GHz
+        */
+       cts_rate = info->control.rts_cts_rate_idx;
+
+       memset(&txhdr->rateset, 0, sizeof(txhdr->rateset));
+
+       /* see how many rates got used */
+       for (i = 0; i < 4; i++) {
+               if (info->control.rates[i].idx < 0)
+                       break;
+               nrates++;
+       }
+
+       /* limit tries to 8/nrates per rate */
+       for (i = 0; i < nrates; i++) {
+               /*
+                * The magic expression here is equivalent to 8/nrates for
+                * all values that matter, but avoids division and jumps.
+                * Note that nrates can only take the values 1 through 4.
+                */
+               calculated_tries[i] = min_t(int, ((15 >> nrates) | 1) + 1,
+                                                info->control.rates[i].count);
+               nremaining -= calculated_tries[i];
        }
-       if (rc_flags & IEEE80211_TX_RC_USE_RTS_CTS) {
-               rate |= 0x40;
-               cts_rate |= ieee80211_get_rts_cts_rate(dev, info)->hw_value;
-       } else if (rc_flags & IEEE80211_TX_RC_USE_CTS_PROTECT) {
-               rate |= 0x20;
-               cts_rate |= ieee80211_get_rts_cts_rate(dev, info)->hw_value;
+
+       /* if there are tries left, distribute from back to front */
+       for (i = nrates - 1; nremaining > 0 && i >= 0; i--) {
+               int tmp = info->control.rates[i].count - calculated_tries[i];
+
+               if (tmp <= 0)
+                       continue;
+               /* RC requested more tries at this rate */
+
+               tmp = min_t(int, tmp, nremaining);
+               calculated_tries[i] += tmp;
+               nremaining -= tmp;
        }
-       memset(txhdr->rateset, rate, 8);
+
+       ridx = 0;
+       for (i = 0; i < nrates && ridx < 8; i++) {
+               /* we register the rates in perfect order */
+               rate = info->control.rates[i].idx;
+               if (info->band == IEEE80211_BAND_5GHZ)
+                       rate += 4;
+
+               /* store the count we actually calculated for TX status */
+               info->control.rates[i].count = calculated_tries[i];
+
+               rc_flags = info->control.rates[i].flags;
+               if (rc_flags & IEEE80211_TX_RC_USE_SHORT_PREAMBLE) {
+                       rate |= 0x10;
+                       cts_rate |= 0x10;
+               }
+               if (rc_flags & IEEE80211_TX_RC_USE_RTS_CTS)
+                       rate |= 0x40;
+               else if (rc_flags & IEEE80211_TX_RC_USE_CTS_PROTECT)
+                       rate |= 0x20;
+               for (j = 0; j < calculated_tries[i] && ridx < 8; j++) {
+                       txhdr->rateset[ridx] = rate;
+                       ridx++;
+               }
+       }
+       hdr->retry2 = ridx;
+
        txhdr->key_type = 0;
        txhdr->key_len = 0;
        txhdr->hw_queue = skb_get_queue_mapping(skb) + 4;
@@ -1393,6 +1469,16 @@ struct ieee80211_hw *p54_init_common(size_t priv_data_len)
        priv->tx_stats[4].limit = 5;
        dev->queues = 1;
        priv->noise = -94;
+       /*
+        * We support at most 8 tries no matter which rate they're at,
+        * we cannot support max_rates * max_rate_tries as we set it
+        * here, but setting it correctly to 4/2 or so would limit us
+        * artificially if the RC algorithm wants just two rates, so
+        * let's say 4/7, we'll redistribute it at TX time, see the
+        * comments there.
+        */
+       dev->max_rates = 4;
+       dev->max_rate_tries = 7;
        dev->extra_tx_headroom = sizeof(struct p54_control_hdr) + 4 +
                                 sizeof(struct p54_tx_control_allocdata);