From 816ac3e6e67bdd78d86226c6eb53619780750e92 Mon Sep 17 00:00:00 2001 From: Felix Fietkau Date: Thu, 22 Apr 2021 22:21:04 -0700 Subject: [PATCH] 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 Signed-off-by: Ilya Lipnitskiy Signed-off-by: David S. Miller --- 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 6d23118..4735942 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 */ -- 2.7.4