Re: [PATCH 2/2] ath9k: fix dma sync in rx path

[Ming Lei <tom.leiming@gmail.com>]

>From edd368e7436e7a80c5a43e7ad40cff1f3fa20806 Mon Sep 17 00:00:00 2001
From: Ming Lei <tom.leiming@gmail.com>
Date: Fri, 14 May 2010 17:35:51 +0800
Subject: [PATCH 2/2] ath9k: fix dma sync in rx path(v2)

If buffer is to be accessed by cpu after dma is over, but
between dma mapping and dma unmapping, we should use
dma_sync_single_for_cpu to sync the buffer between cpu with
device. And dma_sync_single_for_device is used to let
device gain the buffer again.

v2: Felix pointed out dma_sync_single_for_device is needed to return
buffer to device if an unsuccessful status bit check is found.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---
 drivers/net/wireless/ath/ath9k/recv.c |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index a3fe6e1..f4453f0 100644
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -694,12 +694,16 @@ static bool ath_edma_get_buffers(struct ath_softc *sc,
 	bf = SKB_CB_ATHBUF(skb);
 	BUG_ON(!bf);
 
-	dma_sync_single_for_device(sc->dev, bf->bf_buf_addr,
+	dma_sync_single_for_cpu(sc->dev, bf->bf_buf_addr,
 				common->rx_bufsize, DMA_FROM_DEVICE);
 
 	ret = ath9k_hw_process_rxdesc_edma(ah, NULL, skb->data);
-	if (ret == -EINPROGRESS)
+	if (ret == -EINPROGRESS) {
+		/*let device gain the buffer again*/
+		dma_sync_single_for_device(sc->dev, bf->bf_buf_addr,
+				common->rx_bufsize, DMA_FROM_DEVICE);
 		return false;
+	}
 
 	__skb_unlink(skb, &rx_edma->rx_fifo);
 	if (ret == -EINVAL) {
@@ -808,7 +812,7 @@ static struct ath_buf *ath_get_next_rx_buf(struct ath_softc *sc,
 	 * 1. accessing the frame
 	 * 2. requeueing the same buffer to h/w
 	 */
-	dma_sync_single_for_device(sc->dev, bf->bf_buf_addr,
+	dma_sync_single_for_cpu(sc->dev, bf->bf_buf_addr,
 			common->rx_bufsize,
 			DMA_FROM_DEVICE);
 
-- 
1.6.2.5