From 407618d66dba55e7db1278872e8be106808bbe91 Mon Sep 17 00:00:00 2001 From: Maxime Chevallier Date: Fri, 22 Nov 2024 15:12:55 +0100 Subject: [PATCH] net: stmmac: dwmac-socfpga: Set RX watchdog interrupt as broken On DWMAC3 and later, there's a RX Watchdog interrupt that's used for interrupt coalescing. It's known to be buggy on some platforms, and dwmac-socfpga appears to be one of them. Changing the interrupt coalescing from ethtool doesn't appear to have any effect here. Without disabling RIWT (Received Interrupt Watchdog Timer, I believe...), we observe latencies while receiving traffic that amount to around ~0.4ms. This was discovered with NTP but can be easily reproduced with a simple ping. Without this patch : 64 bytes from 192.168.5.2: icmp_seq=1 ttl=64 time=0.657 ms With this patch : 64 bytes from 192.168.5.2: icmp_seq=1 ttl=64 time=0.254 ms Fixes: 801d233b7302 ("net: stmmac: Add SOCFPGA glue driver") Signed-off-by: Maxime Chevallier Link: https://patch.msgid.link/20241122141256.764578-1-maxime.chevallier@bootlin.com Signed-off-by: Paolo Abeni --- drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c index 248b30d7b864..16020b72dec8 100644 --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c @@ -487,6 +487,8 @@ static int socfpga_dwmac_probe(struct platform_device *pdev) plat_dat->select_pcs = socfpga_dwmac_select_pcs; plat_dat->has_gmac = true; + plat_dat->riwt_off = 1; + ret = stmmac_dvr_probe(&pdev->dev, plat_dat, &stmmac_res); if (ret) return ret; -- 2.20.1