[PATCH net-next 11/14] net: ethernet: mtk_eth_soc: only read the full RX descriptor if DMA is done
From: Ilya Lipnitskiy <hidden>
Date: 2021-04-22 04:10:54
Also in:
linux-mediatek, lkml, netdev
Subsystem:
mediatek ethernet driver, networking drivers, the rest · Maintainers:
Felix Fietkau, Lorenzo Bianconi, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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 <redacted> --- 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 01ad10c76d53..5a531bb83348 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c@@ -775,13 +775,18 @@ 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 */
@@ -1253,8 +1258,7 @@ 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
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