[PATCH] ARM: dts: sun7i: pcduino3-nano: enable RGMII RX/TX delay on PHY

[Adam Sampson <ats@offog.org>]

The RX/TX delays for the Ethernet PHY on the Linksprite pcDuino 3 Nano
are configured in hardware, using resistors that are populated to pull
the RTL8211E's RXDLY/TXDLY pins low or high as needed.

phy-mode should be set to rgmii-id to reflect this. Previously it was
set to rgmii, which used to work but now results in the delays being
disabled again as a result of the bugfix in commit bbc4d71d6354 ("net:
phy: realtek: fix rtl8211e rx/tx delay config").

Tested on two pcDuino 3 Nano boards purchased in 2015. Without this fix,
Ethernet works unreliably on one board and doesn't work at all on the
other.

Fixes: 061035d456c9 ("ARM: dts: sun7i: Add dts file for pcDuino 3 Nano board")
Signed-off-by: Adam Sampson <ats@offog.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Chen-Yu Tsai <wens@csie.org>
---
 arch/arm/boot/dts/sun7i-a20-pcduino3-nano.dts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/boot/dts/sun7i-a20-pcduino3-nano.dts b/arch/arm/boot/dts/sun7i-a20-pcduino3-nano.dts
index fce2f7fcd084..bf38c66c1815 100644
--- a/arch/arm/boot/dts/sun7i-a20-pcduino3-nano.dts
+++ b/arch/arm/boot/dts/sun7i-a20-pcduino3-nano.dts
@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 Adam Sampson <ats@offog.org>
+ * Copyright 2015-2020 Adam Sampson <ats@offog.org>
  *
  * This file is dual-licensed: you can use it either under the terms
  * of the GPL or the X11 license, at your option. Note that this dual
@@ -115,7 +115,7 @@ &gmac {
 	pinctrl-names = "default";
 	pinctrl-0 = <&gmac_rgmii_pins>;
 	phy-handle = <&phy1>;
-	phy-mode = "rgmii";
+	phy-mode = "rgmii-id";
 	status = "okay";
 };
 
-- 
2.29.1