mediatek/ramips: unify ethernet driver fixes and add performance optimizations

[openwrt/openwrt.git] / target / linux / generic / pending-5.4 / 770-01-net-ethernet-mtk_eth_soc-significantly-reduce-mdio-b.patch

diff --git a/target/linux/generic/pending-5.4/770-01-net-ethernet-mtk_eth_soc-significantly-reduce-mdio-b.patch b/target/linux/generic/pending-5.4/770-01-net-ethernet-mtk_eth_soc-significantly-reduce-mdio-b.patch
new file mode 100644 (file)
index 0000000..922c35a
--- /dev/null
+++ b/target/linux/generic/pending-5.4/770-01-net-ethernet-mtk_eth_soc-significantly-reduce-mdio-b.patch
@@ -0,0 +1,26 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Mon, 8 Jun 2020 17:02:39 +0200
+Subject: [PATCH] net: ethernet: mtk_eth_soc: significantly reduce mdio bus
+ access latency
+
+usleep_range often ends up sleeping much longer than the 10-20us provided
+as a range here. This causes significant latency in mdio bus acceses,
+which easily adds multiple seconds to the boot time on MT7621 when polling
+DSA slave ports.
+Use cond_resched instead of usleep_range, since the MDIO access does not
+take much time
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
++++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+@@ -85,7 +85,7 @@ static int mtk_mdio_busy_wait(struct mtk
+                       return 0;
+               if (time_after(jiffies, t_start + PHY_IAC_TIMEOUT))
+                       break;
+-              usleep_range(10, 20);
++              cond_resched();
+       }
+ 
+       dev_err(eth->dev, "mdio: MDIO timeout\n");