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;

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>

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 (file)
--- a/doc/device-tree-bindings/phy/phy-mtk-tphy.txt
+++ b/doc/device-tree-bindings/phy/phy-mtk-tphy.txt
@@ -52,6 +52,15 @@ Optional properties (port (child) node):
                  "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: