On 2011-07-11 8:52 AM, Michał Mirosław wrote:
Also constify buf_addr for ath9k_hw_process_rxdesc_edma() to verify
assumptions --- dma_sync_single_for_device() call can be removed.
Signed-off-by: Michał Mirosław<mirq-linux@xxxxxxxxxxxx>
---
drivers/net/wireless/ath/ath9k/ar9003_mac.c | 4 ++--
drivers/net/wireless/ath/ath9k/ar9003_mac.h | 2 +-
drivers/net/wireless/ath/ath9k/recv.c | 10 +++-------
3 files changed, 6 insertions(+), 10 deletions(-)
diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index 70dc8ec..c5f46d5 100644
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -684,15 +684,11 @@ static bool ath_edma_get_buffers(struct ath_softc *sc,
BUG_ON(!bf);
dma_sync_single_for_cpu(sc->dev, bf->bf_buf_addr,
- common->rx_bufsize, DMA_FROM_DEVICE);
+ common->rx_bufsize, DMA_BIDIRECTIONAL);
ret = ath9k_hw_process_rxdesc_edma(ah, NULL, skb->data);
- 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);
+ if (ret == -EINPROGRESS)
return false;
- }
__skb_unlink(skb,&rx_edma->rx_fifo);
if (ret == -EINVAL) {
I have strong doubts about this change. On most MIPS devices,
dma_sync_single_for_cpu is a no-op, whereas dma_sync_single_for_device
flushes the cache range. With this change, the CPU could cache the DMA
status part behind skb->data and that cache entry would not be flushed
inbetween calls to this functions on the same buffer, likely leading to
rx stalls.
- Felix
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