wl1271: Support firmware TX packet aggregation

Instead of sending one packet at a time to the firmware, try to
send all available packets at once.
This optimization decreases the number of transactions, which saves
CPU cycles and increases network throughput.

Signed-off-by: Ido Yariv <ido@wizery.com>
Tested-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>

diff --git a/drivers/net/wireless/wl12xx/wl1271_tx.c b/drivers/net/wireless/wl12xx/wl1271_tx.c
index 1b8295c..e3dc13c 100644 (file)
--- a/drivers/net/wireless/wl12xx/wl1271_tx.c
+++ b/drivers/net/wireless/wl12xx/wl1271_tx.c
@@ -43,13 +43,17 @@ static int wl1271_tx_id(struct wl1271 *wl, struct sk_buff *skb)
        return -EBUSY;
 }
 
-static int wl1271_tx_allocate(struct wl1271 *wl, struct sk_buff *skb, u32 extra)
+static int wl1271_tx_allocate(struct wl1271 *wl, struct sk_buff *skb, u32 extra,
+                               u32 buf_offset)
 {
        struct wl1271_tx_hw_descr *desc;
        u32 total_len = skb->len + sizeof(struct wl1271_tx_hw_descr) + extra;
        u32 total_blocks;
        int id, ret = -EBUSY;
 
+       if (buf_offset + total_len > WL1271_AGGR_BUFFER_SIZE)
+               return -EBUSY;
+
        /* allocate free identifier for the packet */
        id = wl1271_tx_id(wl, skb);
        if (id < 0)
@@ -82,7 +86,7 @@ static int wl1271_tx_allocate(struct wl1271 *wl, struct sk_buff *skb, u32 extra)
        return ret;
 }
 
-static int wl1271_tx_fill_hdr(struct wl1271 *wl, struct sk_buff *skb,
+static void wl1271_tx_fill_hdr(struct wl1271 *wl, struct sk_buff *skb,
                              u32 extra, struct ieee80211_tx_info *control)
 {
        struct timespec ts;
@@ -133,59 +137,17 @@ static int wl1271_tx_fill_hdr(struct wl1271 *wl, struct sk_buff *skb,
        desc->tx_attr = cpu_to_le16(tx_attr);
 
        wl1271_debug(DEBUG_TX, "tx_fill_hdr: pad: %d", pad);
-       return 0;
-}
-
-static int wl1271_tx_send_packet(struct wl1271 *wl, struct sk_buff *skb,
-                                struct ieee80211_tx_info *control)
-{
-
-       struct wl1271_tx_hw_descr *desc;
-       int len;
-
-       /* FIXME: This is a workaround for getting non-aligned packets.
-          This happens at least with EAPOL packets from the user space.
-          Our DMA requires packets to be aligned on a 4-byte boundary.
-       */
-       if (unlikely((long)skb->data & 0x03)) {
-               int offset = (4 - (long)skb->data) & 0x03;
-               wl1271_debug(DEBUG_TX, "skb offset %d", offset);
-
-               /* check whether the current skb can be used */
-               if (!skb_cloned(skb) && (skb_tailroom(skb) >= offset)) {
-                       unsigned char *src = skb->data;
-
-                       /* align the buffer on a 4-byte boundary */
-                       skb_reserve(skb, offset);
-                       memmove(skb->data, src, skb->len);
-               } else {
-                       wl1271_info("No handler, fixme!");
-                       return -EINVAL;
-               }
-       }
-
-       len = WL1271_TX_ALIGN(skb->len);
-
-       /* perform a fixed address block write with the packet */
-       wl1271_write(wl, WL1271_SLV_MEM_DATA, skb->data, len, true);
-
-       /* write packet new counter into the write access register */
-       wl->tx_packets_count++;
-
-       desc = (struct wl1271_tx_hw_descr *) skb->data;
-       wl1271_debug(DEBUG_TX, "tx id %u skb 0x%p payload %u (%u words)",
-                    desc->id, skb, len, desc->length);
-
-       return 0;
 }
 
 /* caller must hold wl->mutex */
-static int wl1271_tx_frame(struct wl1271 *wl, struct sk_buff *skb)
+static int wl1271_prepare_tx_frame(struct wl1271 *wl, struct sk_buff *skb,
+                                                       u32 buf_offset)
 {
        struct ieee80211_tx_info *info;
        u32 extra = 0;
        int ret = 0;
        u8 idx;
+       u32 total_len;
 
        if (!skb)
                return -EINVAL;
@@ -208,19 +170,22 @@ static int wl1271_tx_frame(struct wl1271 *wl, struct sk_buff *skb)
                }
        }
 
-       ret = wl1271_tx_allocate(wl, skb, extra);
+       ret = wl1271_tx_allocate(wl, skb, extra, buf_offset);
        if (ret < 0)
                return ret;
 
-       ret = wl1271_tx_fill_hdr(wl, skb, extra, info);
-       if (ret < 0)
-               return ret;
+       wl1271_tx_fill_hdr(wl, skb, extra, info);
 
-       ret = wl1271_tx_send_packet(wl, skb, info);
-       if (ret < 0)
-               return ret;
+       /*
+        * The length of each packet is stored in terms of words. Thus, we must
+        * pad the skb data to make sure its length is aligned.
+        * The number of padding bytes is computed and set in wl1271_tx_fill_hdr
+        */
+       total_len = WL1271_TX_ALIGN(skb->len);
+       memcpy(wl->aggr_buf + buf_offset, skb->data, skb->len);
+       memset(wl->aggr_buf + buf_offset + skb->len, 0, total_len - skb->len);
 
-       return ret;
+       return total_len;
 }
 
 u32 wl1271_tx_enabled_rates_get(struct wl1271 *wl, u32 rate_set)
@@ -245,7 +210,7 @@ void wl1271_tx_work(struct work_struct *work)
        struct sk_buff *skb;
        bool woken_up = false;
        u32 sta_rates = 0;
-       u32 prev_tx_packets_count;
+       u32 buf_offset;
        int ret;
 
        /* check if the rates supported by the AP have changed */
@@ -262,14 +227,15 @@ void wl1271_tx_work(struct work_struct *work)
        if (unlikely(wl->state == WL1271_STATE_OFF))
                goto out;
 
-       prev_tx_packets_count = wl->tx_packets_count;
-
        /* if rates have changed, re-configure the rate policy */
        if (unlikely(sta_rates)) {
                wl->rate_set = wl1271_tx_enabled_rates_get(wl, sta_rates);
                wl1271_acx_rate_policies(wl);
        }
 
+       /* Prepare the transfer buffer, by aggregating all
+        * available packets */
+       buf_offset = 0;
        while ((skb = skb_dequeue(&wl->tx_queue))) {
                if (!woken_up) {
                        ret = wl1271_ps_elp_wakeup(wl, false);
@@ -278,21 +244,30 @@ void wl1271_tx_work(struct work_struct *work)
                        woken_up = true;
                }
 
-               ret = wl1271_tx_frame(wl, skb);
+               ret = wl1271_prepare_tx_frame(wl, skb, buf_offset);
                if (ret == -EBUSY) {
-                       /* firmware buffer is full, lets stop transmitting. */
+                       /*
+                        * Either the firmware buffer is full, or the
+                        * aggregation buffer is.
+                        * Queue back last skb, and stop aggregating.
+                        */
                        skb_queue_head(&wl->tx_queue, skb);
                        goto out_ack;
                } else if (ret < 0) {
                        dev_kfree_skb(skb);
                        goto out_ack;
                }
+               buf_offset += ret;
+               wl->tx_packets_count++;
        }
 
 out_ack:
-       /* interrupt the firmware with the new packets */
-       if (prev_tx_packets_count != wl->tx_packets_count)
+       if (buf_offset) {
+               wl1271_write(wl, WL1271_SLV_MEM_DATA, wl->aggr_buf,
+                               buf_offset, true);
+               /* interrupt the firmware with the new packets */
                wl1271_write32(wl, WL1271_HOST_WR_ACCESS, wl->tx_packets_count);
+       }
 
 out:
        if (woken_up)