ath5k: use rx hw descriptor pointer for self-linked check

This patch simplifies the code used to detect when the
self-linked DMA buffer is still in use by hardware, by
checking the hardware's rxdp register instead of looking
at the software buffer list.

Signed-off-by: Bob Copeland <me@bobcopeland.com>
Acked-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 4 insertions, 20 deletions

diff --git a/drivers/net/wireless/ath/ath5k/base.c b/drivers/net/wireless/ath/ath5k/base.c
index 3bde18f91450..1a6e72fe7be9 100644
--- a/drivers/net/wireless/ath/ath5k/base.c
+++ b/drivers/net/wireless/ath/ath5k/base.c
@@ -1780,7 +1780,7 @@ ath5k_tasklet_rx(unsigned long data)
         struct sk_buff *skb, *next_skb;
         dma_addr_t next_skb_addr;
         struct ath5k_softc *sc = (void *)data;
-        struct ath5k_buf *bf, *bf_last;
+        struct ath5k_buf *bf;
         struct ath5k_desc *ds;
         int ret;
         int hdrlen;
@@ -1791,7 +1791,6 @@ ath5k_tasklet_rx(unsigned long data)
                 ATH5K_WARN(sc, "empty rx buf pool\n");
                 goto unlock;
         }
-        bf_last = list_entry(sc->rxbuf.prev, struct ath5k_buf, list);
         do {
                 rxs.flag = 0;
 
@@ -1800,24 +1799,9 @@ ath5k_tasklet_rx(unsigned long data)
                 skb = bf->skb;
                 ds = bf->desc;
 
-                /*
-                 * last buffer must not be freed to ensure proper hardware
-                 * function. When the hardware finishes also a packet next to
-                 * it, we are sure, it doesn't use it anymore and we can go on.
-                 */
-                if (bf_last == bf)
-                        bf->flags |= 1;
-                if (bf->flags) {
-                        struct ath5k_buf *bf_next = list_entry(bf->list.next,
-                                        struct ath5k_buf, list);
-                        ret = sc->ah->ah_proc_rx_desc(sc->ah, bf_next->desc,
-                                        &rs);
-                        if (ret)
-                                break;
-                        bf->flags &= ~1;
-                        /* skip the overwritten one (even status is martian) */
-                        goto next;
-                }
+                /* bail if HW is still using self-linked descriptor */
+                if (ath5k_hw_get_rxdp(sc->ah) == bf->daddr)
+                        break;
 
                 ret = sc->ah->ah_proc_rx_desc(sc->ah, ds, &rs);
                 if (unlikely(ret == -EINPROGRESS))