The StarFive VisionFive V1 SBC uses a Motorcomm YT8521 PHY supporting
RGMII-ID, but requires manual adjustment of the RX internal delay to
work properly.
The default RX delay provided by the driver is 1.95 ns, which proves to
be too high. Applying a 50% reduction seems to mitigate the issue.
Also note this adjustment is not necessary on BeagleV Starlight SBC,
which uses a Microchip PHY. Hence, there is no indication of a
misbehaviour on the GMAC side, but most likely the issue stems from
the Motorcomm PHY.
While at it, drop the redundant gpio include, which is already provided
by jh7100-common.dtsi.
Co-developed-by: Emil Renner Berthing <emil.renner.berthing@xxxxxxxxxxxxx>
Signed-off-by: Emil Renner Berthing <emil.renner.berthing@xxxxxxxxxxxxx>
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@xxxxxxxxxxxxx>
---
.../jh7100-starfive-visionfive-v1.dts | 22 ++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/boot/dts/starfive/jh7100-starfive-visionfive-v1.dts b/arch/riscv/boot/dts/starfive/jh7100-starfive-visionfive-v1.dts
index e82af72f1aaf..4e396f820660 100644
--- a/arch/riscv/boot/dts/starfive/jh7100-starfive-visionfive-v1.dts
+++ b/arch/riscv/boot/dts/starfive/jh7100-starfive-visionfive-v1.dts
@@ -6,7 +6,6 @@
/dts-v1/;
#include "jh7100-common.dtsi"
-#include <dt-bindings/gpio/gpio.h>
/ {
model = "StarFive VisionFive V1";
@@ -18,3 +17,24 @@ gpio-restart {
priority = <224>;
};
};
+
+/*
+ * The board uses a Motorcomm YT8521 PHY supporting RGMII-ID, but requires
+ * manual adjustment of the RX internal delay to work properly. The default
+ * RX delay provided by the driver (1.95ns) is too high, but applying a 50%
+ * reduction seems to mitigate the issue.
+ *
+ * It is worth noting the adjustment is not necessary on BeagleV Starlight SBC,
+ * which uses a Microchip PHY. Hence, most likely the Motorcomm PHY is the one
+ * responsible for the misbehaviour, not the GMAC.
+ */
+&mdio {
+ phy: ethernet-phy@0 {
+ reg = <0>;
+ rx-internal-delay-ps = <900>;
+ };
+};
+
+&gmac {
+ phy-handle = <&phy>;
+};
--
2.43.0
