diff mbox series

[net-next,v2,11/15] net: ethernet: mtk_eth_soc: only read the full RX descriptor if DMA is done

Message ID 20210423052108.423853-12-ilya.lipnitskiy@gmail.com (mailing list archive)
State Accepted
Commit 816ac3e6e67bdd78d86226c6eb53619780750e92
Delegated to: Netdev Maintainers
Headers show
Series mtk_eth_soc: fixes and performance improvements | expand

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netdev/source_inline warning Was 1 now: 1
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netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 0 this patch: 0
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netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 29 lines checked
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Commit Message

Ilya Lipnitskiy April 23, 2021, 5:21 a.m. UTC 
From: Felix Fietkau <nbd@nbd.name>

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>
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 6d23118b7a6c..4735942ed283 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -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 */