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From: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
To: Felix Fietkau <nbd@nbd.name>, John Crispin <john@phrozen.org>,
	Sean Wang <sean.wang@mediatek.com>,
	Mark Lee <Mark-MC.Lee@mediatek.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org
Cc: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
Subject: [PATCH net-next v2 11/15] net: ethernet: mtk_eth_soc: only read the full RX descriptor if DMA is done
Date: Thu, 22 Apr 2021 22:21:04 -0700	[thread overview]
Message-ID: <20210423052108.423853-12-ilya.lipnitskiy@gmail.com> (raw)
In-Reply-To: <20210423052108.423853-1-ilya.lipnitskiy@gmail.com>

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 --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 */
-- 
2.31.1


  parent reply	other threads:[~2021-04-23  5:22 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-23  5:20 [PATCH net-next v2 00/15] mtk_eth_soc: fixes and performance improvements Ilya Lipnitskiy
2021-04-23  5:20 ` [PATCH net-next v2 01/15] net: ethernet: mtk_eth_soc: fix RX VLAN offload Ilya Lipnitskiy
2021-04-23  5:20 ` [PATCH net-next v2 02/15] net: ethernet: mtk_eth_soc: unmap RX data before calling build_skb Ilya Lipnitskiy
2021-04-23  5:20 ` [PATCH net-next v2 03/15] net: ethernet: mtk_eth_soc: fix build_skb cleanup Ilya Lipnitskiy
2021-04-23  5:20 ` [PATCH net-next v2 04/15] net: ethernet: mtk_eth_soc: use napi_consume_skb Ilya Lipnitskiy
2021-04-23  5:20 ` [PATCH net-next v2 05/15] net: ethernet: mtk_eth_soc: reduce MDIO bus access latency Ilya Lipnitskiy
2021-04-23  5:20 ` [PATCH net-next v2 06/15] net: ethernet: mtk_eth_soc: remove unnecessary TX queue stops Ilya Lipnitskiy
2021-04-23  5:21 ` [PATCH net-next v2 07/15] net: ethernet: mtk_eth_soc: use larger burst size for QDMA TX Ilya Lipnitskiy
2021-04-23  5:21 ` [PATCH net-next v2 08/15] net: ethernet: mtk_eth_soc: increase DMA ring sizes Ilya Lipnitskiy
2021-04-23  5:21 ` [PATCH net-next v2 09/15] net: ethernet: mtk_eth_soc: implement dynamic interrupt moderation Ilya Lipnitskiy
2021-04-23  5:21 ` [PATCH net-next v2 10/15] net: ethernet: mtk_eth_soc: cache HW pointer of last freed TX descriptor Ilya Lipnitskiy
2021-04-23  5:21 ` Ilya Lipnitskiy [this message]
2021-04-23  5:21 ` [PATCH net-next v2 12/15] net: ethernet: mtk_eth_soc: reduce unnecessary interrupts Ilya Lipnitskiy
2021-04-23  5:21 ` [PATCH net-next v2 13/15] net: ethernet: mtk_eth_soc: rework NAPI callbacks Ilya Lipnitskiy
2021-04-23  5:21 ` [PATCH net-next v2 14/15] net: ethernet: mtk_eth_soc: set PPE flow hash as skb hash if present Ilya Lipnitskiy
2021-04-23  5:21 ` [PATCH net-next v2 15/15] net: ethernet: mtk_eth_soc: use iopoll.h macro for DMA init Ilya Lipnitskiy
2021-04-23 21:00 ` [PATCH net-next v2 00/15] mtk_eth_soc: fixes and performance improvements patchwork-bot+netdevbpf

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