[RFC][NET] Alignment in mv643xx_eth

[RFC][NET] Alignment in mv643xx_eth

[Ralf Baechle]

The driver contains this little piece of candy:

#if defined(CONFIG_DMA_NONCOHERENT) || defined(CONFIG_NOT_COHERENT_CACHE)
#define ETH_DMA_ALIGN           L1_CACHE_BYTES
#else
#define ETH_DMA_ALIGN           8
#endif

Any reason why we're not using dma_get_cache_alignment() instead?

  Ralf

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c
index d98e53e..3e045a6 100644
--- a/drivers/net/mv643xx_eth.c
+++ b/drivers/net/mv643xx_eth.c
@@ -147,13 +147,13 @@ static void mv643xx_eth_rx_refill_descs(struct net_device *dev)
 	int unaligned;
 
 	while (mp->rx_desc_count < mp->rx_ring_size) {
-		skb = dev_alloc_skb(ETH_RX_SKB_SIZE + ETH_DMA_ALIGN);
+		skb = dev_alloc_skb(ETH_RX_SKB_SIZE + dma_get_cache_alignment());
 		if (!skb)
 			break;
 		mp->rx_desc_count++;
-		unaligned = (u32)skb->data & (ETH_DMA_ALIGN - 1);
+		unaligned = (u32)skb->data & (dma_get_cache_alignment() - 1);
 		if (unaligned)
-			skb_reserve(skb, ETH_DMA_ALIGN - unaligned);
+			skb_reserve(skb, dma_get_cache_alignment() - unaligned);
 		pkt_info.cmd_sts = ETH_RX_ENABLE_INTERRUPT;
 		pkt_info.byte_cnt = ETH_RX_SKB_SIZE;
 		pkt_info.buf_ptr = dma_map_single(NULL, skb->data,
diff --git a/drivers/net/mv643xx_eth.h b/drivers/net/mv643xx_eth.h
index 33c5faf..7cb0a41 100644
--- a/drivers/net/mv643xx_eth.h
+++ b/drivers/net/mv643xx_eth.h
@@ -42,17 +42,6 @@
 #define MAX_DESCS_PER_SKB	1
 #endif
 
-/*
- * The MV643XX HW requires 8-byte alignment.  However, when I/O
- * is non-cache-coherent, we need to ensure that the I/O buffers
- * we use don't share cache lines with other data.
- */
-#if defined(CONFIG_DMA_NONCOHERENT) || defined(CONFIG_NOT_COHERENT_CACHE)
-#define ETH_DMA_ALIGN		L1_CACHE_BYTES
-#else
-#define ETH_DMA_ALIGN		8
-#endif
-
 #define ETH_VLAN_HLEN		4
 #define ETH_FCS_LEN		4
 #define ETH_HW_IP_ALIGN		2		/* hw aligns IP header */

Re: [RFC][NET] Alignment in mv643xx_eth

[Dale Farnsworth]

On Mon, Feb 26, 2007 at 07:52:06PM +0000, Ralf Baechle wrote:
> The driver contains this little piece of candy:
> 
> #if defined(CONFIG_DMA_NONCOHERENT) || defined(CONFIG_NOT_COHERENT_CACHE)
> #define ETH_DMA_ALIGN           L1_CACHE_BYTES
> #else
> #define ETH_DMA_ALIGN           8
> #endif
> 
> Any reason why we're not using dma_get_cache_alignment() instead?

Not that I can think of.

ACK.

Dale Farnsworth

Re: [RFC][NET] Alignment in mv643xx_eth

[Jeff Garzik]

Ralf Baechle wrote:
> The driver contains this little piece of candy:
> 
> #if defined(CONFIG_DMA_NONCOHERENT) || defined(CONFIG_NOT_COHERENT_CACHE)
> #define ETH_DMA_ALIGN           L1_CACHE_BYTES
> #else
> #define ETH_DMA_ALIGN           8
> #endif
> 
> Any reason why we're not using dma_get_cache_alignment() instead?
> 
>   Ralf
> 
> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

applied