[PATCH 2/7] rt2x00: Map extra_tx_headroom to DMA
From: Ivo van Doorn <hidden>
Date: 2008-08-29 19:07:57
Subsystem:
networking drivers (wireless), the rest · Maintainers:
Johannes Berg, Linus Torvalds
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 <redacted> --- 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