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>

diff --git a/arch/arm64/boot/dts/rockchip/rk3328.dtsi b/arch/arm64/boot/dts/rockchip/rk3328.dtsi
index bad41bc6f2d586828890b6e39bcf76ce16c16e13..2aefb38f7368f0a59947f177f5fb6e1522cea765 100644 (file)
--- a/arch/arm64/boot/dts/rockchip/rk3328.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3328.dtsi
@@ -906,6 +906,7 @@
                resets = <&cru SRST_GMAC2IO_A>;
                reset-names = "stmmaceth";
                rockchip,grf = <&grf>;
+               snps,txpbl = <0x4>;
                status = "disabled";
        };
 
@@ -927,6 +928,7 @@
                reset-names = "stmmaceth", "mac-phy";
                phy-mode = "rmii";
                phy-handle = <&phy>;
+               snps,txpbl = <0x4>;
                status = "disabled";
 
                mdio {

diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
index 33cc21fcf4c10ffe6009bfd3f871aed68b3c77ba..cd5415d7e55952a30dbecb55ff577dd51344bae5 100644 (file)
--- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
@@ -288,6 +288,7 @@
                resets = <&cru SRST_A_GMAC>;
                reset-names = "stmmaceth";
                rockchip,grf = <&grf>;
+               snps,txpbl = <0x4>;
                status = "disabled";
        };