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net: ethernet: mtk_eth_soc: only read the full RX descriptor if DMA is done 

Uncached memory access is expensive, and there is no need to access all
descriptor words if we can't process them anyway

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Felix Fietkau 2021-04-22 22:21:04 -07:00 committed by David S. Miller
parent 4e6bf60956
commit 816ac3e6e6
1 changed files with 8 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/net/ethernet/mediatek/mtk_eth_soc.c
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@ -777,13 +777,18 @@ static inline int mtk_max_buf_size(int frag_size)
return buf_size;
}
static inline void mtk_rx_get_desc(struct mtk_rx_dma *rxd,
static inline bool mtk_rx_get_desc(struct mtk_rx_dma *rxd,
struct mtk_rx_dma *dma_rxd)
{
rxd->rxd1 = READ_ONCE(dma_rxd->rxd1);
rxd->rxd2 = READ_ONCE(dma_rxd->rxd2);
if (!(rxd->rxd2 & RX_DMA_DONE))
return false;
rxd->rxd1 = READ_ONCE(dma_rxd->rxd1);
rxd->rxd3 = READ_ONCE(dma_rxd->rxd3);
rxd->rxd4 = READ_ONCE(dma_rxd->rxd4);
return true;
}
/* the qdma core needs scratch memory to be setup */
@ -1255,8 +1260,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
rxd = &ring->dma[idx];
data = ring->data[idx];
mtk_rx_get_desc(&trxd, rxd);
if (!(trxd.rxd2 & RX_DMA_DONE))
if (!mtk_rx_get_desc(&trxd, rxd))
break;
/* find out which mac the packet come from. values start at 1 */