If a driver requests additional headroom it should
be mapped to DMA as well because it will be send to
the hardware as well (as form of extra descriptor).
Signed-off-by: Ivo van Doorn <IvDoorn@xxxxxxxxx>
---
John, this one is for 2.6.28
---
drivers/net/wireless/rt2x00/rt2x00queue.c | 24 +++++++++++++++++++++---
1 files changed, 21 insertions(+), 3 deletions(-)
diff --git a/drivers/net/wireless/rt2x00/rt2x00queue.c b/drivers/net/wireless/rt2x00/rt2x00queue.c
index d10a801..2822684 100644
--- a/drivers/net/wireless/rt2x00/rt2x00queue.c
+++ b/drivers/net/wireless/rt2x00/rt2x00queue.c
@@ -100,8 +100,21 @@ void rt2x00queue_map_txskb(struct rt2x00_dev *rt2x00dev, struct sk_buff *skb)
{
struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
- skbdesc->skb_dma = dma_map_single(rt2x00dev->dev, skb->data, skb->len,
- DMA_TO_DEVICE);
+ /*
+ * If device has requested headroom, we should make sure that
+ * is also mapped to the DMA so it can be used for transfering
+ * additional descriptor information to the hardware.
+ */
+ skb_push(skb, rt2x00dev->hw->extra_tx_headroom);
+
+ skbdesc->skb_dma =
+ dma_map_single(rt2x00dev->dev, skb->data, skb->len, DMA_TO_DEVICE);
+
+ /*
+ * Restore data pointer to original location again.
+ */
+ skb_pull(skb, rt2x00dev->hw->extra_tx_headroom);
+
skbdesc->flags |= SKBDESC_DMA_MAPPED_TX;
}
EXPORT_SYMBOL_GPL(rt2x00queue_map_txskb);
@@ -117,7 +130,12 @@ void rt2x00queue_unmap_skb(struct rt2x00_dev *rt2x00dev, struct sk_buff *skb)
}
if (skbdesc->flags & SKBDESC_DMA_MAPPED_TX) {
- dma_unmap_single(rt2x00dev->dev, skbdesc->skb_dma, skb->len,
+ /*
+ * Add headroom to the skb length, it has been removed
+ * by the driver, but it was actually mapped to DMA.
+ */
+ dma_unmap_single(rt2x00dev->dev, skbdesc->skb_dma,
+ skb->len + rt2x00dev->hw->extra_tx_headroom,
DMA_TO_DEVICE);
skbdesc->flags &= ~SKBDESC_DMA_MAPPED_TX;
}
--
1.5.6.1
--
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