From 8a469ee35606ba65448d54e5a2a23302f7e79e3c Mon Sep 17 00:00:00 2001
From: Carlos de Paula <me@carlosedp.com>
Date: Tue, 18 Feb 2020 17:10:37 -0500
Subject: [PATCH] arm64: dts: rockchip: Add txpbl node for RK3399/RK3328

Some rockchip SoCs like the RK3399 and RK3328 exhibit an issue
where tx checksumming does not work with packets larger than 1498.

The default Programmable Buffer Length for TX in these GMAC's is
not suitable for MTUs higher than 1498. The workaround is to disable
TX offloading with 'ethtool -K eth0 tx off rx off' causing performance
impacts as it disables hardware checksumming.

This patch sets snps,txpbl to 0x4 which is a safe number tested ok for
the most popular MTU value of 1500.

For reference, see https://lkml.org/lkml/2019/4/1/1382.

Signed-off-by: Carlos de Paula <me@carlosedp.com>
Link: https://lore.kernel.org/r/20200218221040.10955-1-me@carlosedp.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
---
 arch/arm64/boot/dts/rockchip/rk3328.dtsi | 2 ++
 arch/arm64/boot/dts/rockchip/rk3399.dtsi | 1 +
 2 files changed, 3 insertions(+)

--- a/arch/arm64/boot/dts/rockchip/rk3328.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3328.dtsi
@@ -729,6 +729,7 @@
 		resets = <&cru SRST_GMAC2IO_A>;
 		reset-names = "stmmaceth";
 		rockchip,grf = <&grf>;
+		snps,txpbl = <0x4>;
 		status = "disabled";
 	};
 
@@ -750,6 +751,7 @@
 		reset-names = "stmmaceth", "mac-phy";
 		phy-mode = "rmii";
 		phy-handle = <&phy>;
+		snps,txpbl = <0x4>;
 		status = "disabled";
 
 		mdio {
--- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
@@ -290,6 +290,7 @@
 		resets = <&cru SRST_A_GMAC>;
 		reset-names = "stmmaceth";
 		rockchip,grf = <&grf>;
+		snps,txpbl = <0x4>;
 		status = "disabled";
 	};
 
