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Subject[PATCH AUTOSEL 4.19 108/192] ARM: dts: meson8b: fix the Ethernet data line signals in eth_rgmii_pins
Date
From: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

[ Upstream commit 29f0023d01f063feacfc404f0446905aee4f82ee ]

According to the Odroid-C1+ schematics the Ethernet TXD1 signal is
routed to GPIOH_5 and the TXD0 signal is routed to GPIOH_6.
The public S805 datasheet shows that TXD0 can be routed to DIF_2_P and
TXD1 can be routed to DIF_2_N instead.

The pin groups eth_txd0_0 (GPIOH_6) and eth_txd0_1 (DIF_2_P) are both
configured as Ethernet TXD0 and TXD1 data lines in meson8b.dtsi. At the
same time eth_txd1_0 (GPIOH_5) and eth_txd1_1 (DIF_2_N) are configured
as TXD0 and TXD1 data lines as well.
This results in a bad Ethernet receive performance. Presumably this is
due to the eth_txd0 and eth_txd1 signal being routed to the wrong pins.
As a result of that data can only be transmitted on eth_txd2 and
eth_txd3. However, I have no scope to fully confirm this assumption.

The vendor u-boot sources for Odroid-C1 use the following Ethernet
pinmux configuration:
SET_CBUS_REG_MASK(PERIPHS_PIN_MUX_6, 0x3f4f);
SET_CBUS_REG_MASK(PERIPHS_PIN_MUX_7, 0xf00000);
This translates to the following pin groups in the mainline kernel:
- register 6 bit 0: eth_rxd1 (DIF_0_P)
- register 6 bit 1: eth_rxd0 (DIF_0_N)
- register 6 bit 2: eth_rx_dv (DIF_1_P)
- register 6 bit 3: eth_rx_clk (DIF_1_N)
- register 6 bit 6: eth_tx_en (DIF_3_P)
- register 6 bit 8: eth_ref_clk (DIF_3_N)
- register 6 bit 9: eth_mdc (DIF_4_P)
- register 6 bit 10: eth_mdio_en (DIF_4_N)
- register 6 bit 11: eth_tx_clk (GPIOH_9)
- register 6 bit 12: eth_txd2 (GPIOH_8)
- register 6 bit 13: eth_txd3 (GPIOH_7)
- register 7 bit 20: eth_txd0_0 (GPIOH_6)
- register 7 bit 21: eth_txd1_0 (GPIOH_5)
- register 7 bit 22: eth_rxd3 (DIF_2_P)
- register 7 bit 23: eth_rxd2 (DIF_2_N)

Drop the eth_txd0_1 and eth_txd1_1 groups from eth_rgmii_pins to fix the
Ethernet transmit performance on Odroid-C1. Also add the eth_rxd2 and
eth_rxd3 groups so we don't rely on the bootloader to set them up.

iperf3 statistics before this change:
- transmitting from Odroid-C1: 741 Mbits/sec (0 retries)
- receiving on Odroid-C1: 199 Mbits/sec (1713 retries)

iperf3 statistics after this change:
- transmitting from Odroid-C1: 667 Mbits/sec (0 retries)
- receiving on Odroid-C1: 750 Mbits/sec (0 retries)

Fixes: b96446541d8390 ("ARM: dts: meson8b: extend ethernet controller description")
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: Emiliano Ingrassia <ingrassia@epigenesys.com>
Cc: Linus Lüssing <linus.luessing@c0d3.blue>
Tested-by: Emiliano Ingrassia <ingrassia@epigenesys.com>
Reviewed-by: Emiliano Ingrassia <ingrassia@epigenesys.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm/boot/dts/meson8b.dtsi | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm/boot/dts/meson8b.dtsi b/arch/arm/boot/dts/meson8b.dtsi
index 08f7f6be7254..5b3e5c50c72f 100644
--- a/arch/arm/boot/dts/meson8b.dtsi
+++ b/arch/arm/boot/dts/meson8b.dtsi
@@ -207,9 +207,7 @@
groups = "eth_tx_clk",
"eth_tx_en",
"eth_txd1_0",
- "eth_txd1_1",
"eth_txd0_0",
- "eth_txd0_1",
"eth_rx_clk",
"eth_rx_dv",
"eth_rxd1",
@@ -218,7 +216,9 @@
"eth_mdc",
"eth_ref_clk",
"eth_txd2",
- "eth_txd3";
+ "eth_txd3",
+ "eth_rxd3",
+ "eth_rxd2";
function = "ethernet";
};
};
--
2.19.1
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