net: ethernet: mediatek: enhance RX path by reducing the frequency of the memory...

The patch makes move wmb() to outside the loop that could help
RX path handling more faster although that RX descriptors aren't
freed for DMA to use as soon as possible, but based on my experiment
and the result shows it still can reach about 943Mbpis without
performance drop that is tested based on the setup with one port
using Giga PHY and 256 RX descriptors for DMA to move.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 2dadfa961898b806aa164c306a8f79bf97c48437..b43700587c8815ac58910ad57c32dc49247ee54e 100644 (file)
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -895,13 +895,14 @@ release_desc:
                rxd->rxd2 = RX_DMA_PLEN0(ring->buf_size);
 
                ring->calc_idx = idx;
-               /* make sure that all changes to the dma ring are flushed before
-                * we continue
-                */
-               wmb();
-               mtk_w32(eth, ring->calc_idx, MTK_PRX_CRX_IDX0);
+
                done++;
        }
+       /* make sure that all changes to the dma ring are flushed before
+        * we continue
+        */
+       wmb();
+       mtk_w32(eth, ring->calc_idx, MTK_PRX_CRX_IDX0);
 
        if (done < budget)
                mtk_w32(eth, MTK_RX_DONE_INT, MTK_PDMA_INT_STATUS);