dt-bindings: phy-mtk-tphy: add properties for phy tuning
Add properties to improve eye diagram which sometimes need adjust
some parameters of u2phy;
Add a property to tune disconnect threshold;
diff --git a/doc/device-tree-bindings/phy/phy-mtk-tphy.txt b/doc/device-tree-bindings/phy/phy-mtk-tphy.txt
index 3042c39..300e236 100644
--- a/doc/device-tree-bindings/phy/phy-mtk-tphy.txt
+++ b/doc/device-tree-bindings/phy/phy-mtk-tphy.txt
@@ -52,6 +52,15 @@
"da_ref": the reference clock of analog phy, used if the clocks
of analog and digital phys are separated, otherwise uses
"ref" clock only if needed.
+- mediatek,eye-vrt : The selection of VRT reference voltage (U2 phy),
+ the value is [1, 7]
+- mediatek,eye-term : The selection of HS_TX TERM reference voltage (U2 phy),
+ the value is [1, 7]
+- mediatek,discth : The selection of disconnect threshold (U2 phy),
+ the value is [1, 15]
+- mediatek,pre-emphasis : The level of pre-emphasis which used to widen
+ the eye opening and boost eye swing,
+ the value is [1, 3]
Example: