From 9759f1d722aab4cc1efd4af4b80fc2a7100bad17 Mon Sep 17 00:00:00 2001 From: Masaru Nagai Date: Thu, 7 Mar 2019 11:24:47 +0100 Subject: [PATCH] ravb: Decrease TxFIFO depth of Q3 and Q2 to one [ Upstream commit ae9819e339b451da7a86ab6fe38ecfcb6814e78a ] Hardware has the CBS (Credit Based Shaper) which affects only Q3 and Q2. When updating the CBS settings, even if the driver does so after waiting for Tx DMA finished, there is a possibility that frame data still remains in TxFIFO. To avoid this, decrease TxFIFO depth of Q3 and Q2 to one. This patch has been exercised this using netperf TCP_MAERTS, TCP_STREAM and UDP_STREAM tests run on an Ebisu board. No performance change was detected, outside of noise in the tests, both in terms of throughput and CPU utilisation. Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper") Signed-off-by: Masaru Nagai Signed-off-by: Kazuya Mizuguchi [simon: updated changelog] Signed-off-by: Simon Horman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman Signed-off-by: Yang Yingliang --- drivers/net/ethernet/renesas/ravb_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c index 8441c86d9f3b..5f092bbd0514 100644 --- a/drivers/net/ethernet/renesas/ravb_main.c +++ b/drivers/net/ethernet/renesas/ravb_main.c @@ -459,7 +459,7 @@ static int ravb_dmac_init(struct net_device *ndev) RCR_EFFS | RCR_ENCF | RCR_ETS0 | RCR_ESF | 0x18000000, RCR); /* Set FIFO size */ - ravb_write(ndev, TGC_TQP_AVBMODE1 | 0x00222200, TGC); + ravb_write(ndev, TGC_TQP_AVBMODE1 | 0x00112200, TGC); /* Timestamp enable */ ravb_write(ndev, TCCR_TFEN, TCCR); -- GitLab