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lan743x: sync only the received area of an rx ring buffer 

On cpu architectures w/o dma cache snooping, dma_unmap() is a
is a very expensive operation, because its resulting sync
needs to invalidate cpu caches.

Increase efficiency/performance by syncing only those sections
of the lan743x's rx ring buffers that are actually in use.

Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com>
Reviewed-by: Bryan Whitehead <Bryan.Whitehead@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Sven Van Asbroeck 2021-02-15 20:08:03 -05:00 committed by David S. Miller
parent a8db76d40e
commit 966df6ded2
1 changed files with 26 additions and 9 deletions
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35
drivers/net/ethernet/microchip/lan743x_main.c
View File

@ -1939,35 +1939,52 @@ static int lan743x_rx_init_ring_element(struct lan743x_rx *rx, int index)
struct net_device *netdev = rx->adapter->netdev;
struct device *dev = &rx->adapter->pdev->dev;
struct lan743x_rx_buffer_info *buffer_info;
unsigned int buffer_length, used_length;
struct lan743x_rx_descriptor *descriptor;
struct sk_buff *skb;
dma_addr_t dma_ptr;
int length;
length = netdev->mtu + ETH_HLEN + 4 + RX_HEAD_PADDING;
buffer_length = netdev->mtu + ETH_HLEN + 4 + RX_HEAD_PADDING;
descriptor = &rx->ring_cpu_ptr[index];
buffer_info = &rx->buffer_info[index];
skb = __netdev_alloc_skb(netdev, length, GFP_ATOMIC | GFP_DMA);
skb = __netdev_alloc_skb(netdev, buffer_length, GFP_ATOMIC | GFP_DMA);
if (!skb)
return -ENOMEM;
dma_ptr = dma_map_single(dev, skb->data, length, DMA_FROM_DEVICE);
dma_ptr = dma_map_single(dev, skb->data, buffer_length, DMA_FROM_DEVICE);
if (dma_mapping_error(dev, dma_ptr)) {
dev_kfree_skb_any(skb);
return -ENOMEM;
}
if (buffer_info->dma_ptr)
dma_unmap_single(dev, buffer_info->dma_ptr,
buffer_info->buffer_length, DMA_FROM_DEVICE);
if (buffer_info->dma_ptr) {
/* sync used area of buffer only */
if (le32_to_cpu(descriptor->data0) & RX_DESC_DATA0_LS_)
/* frame length is valid only if LS bit is set.
* it's a safe upper bound for the used area in this
* buffer.
*/
used_length = min(RX_DESC_DATA0_FRAME_LENGTH_GET_
(le32_to_cpu(descriptor->data0)),
buffer_info->buffer_length);
else
used_length = buffer_info->buffer_length;
dma_sync_single_for_cpu(dev, buffer_info->dma_ptr,
used_length,
DMA_FROM_DEVICE);
dma_unmap_single_attrs(dev, buffer_info->dma_ptr,
buffer_info->buffer_length,
DMA_FROM_DEVICE,
DMA_ATTR_SKIP_CPU_SYNC);
}
buffer_info->skb = skb;
buffer_info->dma_ptr = dma_ptr;
buffer_info->buffer_length = length;
buffer_info->buffer_length = buffer_length;
descriptor->data1 = cpu_to_le32(DMA_ADDR_LOW32(buffer_info->dma_ptr));
descriptor->data2 = cpu_to_le32(DMA_ADDR_HIGH32(buffer_info->dma_ptr));
descriptor->data3 = 0;
descriptor->data0 = cpu_to_le32((RX_DESC_DATA0_OWN_ |
(length & RX_DESC_DATA0_BUF_LENGTH_MASK_)));
(buffer_length & RX_DESC_DATA0_BUF_LENGTH_MASK_)));
lan743x_rx_update_tail(rx, index);
return 0;