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>

1 files changed, 37 insertions, 62 deletions

diff --git a/drivers/net/wireless/wl12xx/wl1271_tx.c b/drivers/net/wireless/wl12xx/wl1271_tx.c
index 1b8295c5dde4..e3dc13c4d01a 100644
--- 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)