mv643xx_eth: enforce multiple-of-8-bytes receive buffer size restriction
The mv643xx_eth hardware ignores the lower three bits of the buffer
size field in receive descriptors, causing the reception of full-sized
packets to fail at some MTUs. Fix this by rounding the size of
allocated receive buffers up to a multiple of eight bytes.
While we are at it, add a bit of extra space to each receive buffer so
that we can handle multiple vlan tags on ingress.
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c
index e33dfc0..a02a5f4 100644
--- a/drivers/net/mv643xx_eth.c
+++ b/drivers/net/mv643xx_eth.c
@@ -474,11 +474,19 @@
/*
* Reserve 2+14 bytes for an ethernet header (the
* hardware automatically prepends 2 bytes of dummy
- * data to each received packet), 4 bytes for a VLAN
- * header, and 4 bytes for the trailing FCS -- 24
- * bytes total.
+ * data to each received packet), 16 bytes for up to
+ * four VLAN tags, and 4 bytes for the trailing FCS
+ * -- 36 bytes total.
*/
- skb_size = mp->dev->mtu + 24;
+ skb_size = mp->dev->mtu + 36;
+
+ /*
+ * Make sure that the skb size is a multiple of 8
+ * bytes, as the lower three bits of the receive
+ * descriptor's buffer size field are ignored by
+ * the hardware.
+ */
+ skb_size = (skb_size + 7) & ~7;
skb = dev_alloc_skb(skb_size + dma_get_cache_alignment() - 1);
if (skb == NULL)
@@ -552,7 +560,7 @@
spin_unlock_irqrestore(&mp->lock, flags);
dma_unmap_single(NULL, rx_desc->buf_ptr + 2,
- mp->dev->mtu + 24, DMA_FROM_DEVICE);
+ rx_desc->buf_size, DMA_FROM_DEVICE);
rxq->rx_desc_count--;
rx++;