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-rw-r--r--Documentation/devicetree/bindings/net/mscc-phy-vsc8531.txt51
1 files changed, 28 insertions, 23 deletions
diff --git a/Documentation/devicetree/bindings/net/mscc-phy-vsc8531.txt b/Documentation/devicetree/bindings/net/mscc-phy-vsc8531.txt
index 99c7eb0a00c8..bdefefc66594 100644
--- a/Documentation/devicetree/bindings/net/mscc-phy-vsc8531.txt
+++ b/Documentation/devicetree/bindings/net/mscc-phy-vsc8531.txt
@@ -6,22 +6,27 @@ Required properties:
Documentation/devicetree/bindings/net/phy.txt
Optional properties:
-- vsc8531,vddmac : The vddmac in mV.
+- vsc8531,vddmac : The vddmac in mV. Allowed values is listed
+ in the first row of Table 1 (below).
+ This property is only used in combination
+ with the 'edge-slowdown' property.
+ Default value is 3300.
- vsc8531,edge-slowdown : % the edge should be slowed down relative to
- the fastest possible edge time. Native sign
- need not enter.
+ the fastest possible edge time.
Edge rate sets the drive strength of the MAC
- interface output signals. Changing the drive
- strength will affect the edge rate of the output
- signal. The goal of this setting is to help
- reduce electrical emission (EMI) by being able
- to reprogram drive strength and in effect slow
- down the edge rate if desired. Table 1 shows the
- impact to the edge rate per VDDMAC supply for each
- drive strength setting.
- Ref: Table:1 - Edge rate change below.
-
-Note: see dt-bindings/net/mscc-phy-vsc8531.h for applicable values
+ interface output signals. Changing the
+ drive strength will affect the edge rate of
+ the output signal. The goal of this setting
+ is to help reduce electrical emission (EMI)
+ by being able to reprogram drive strength
+ and in effect slow down the edge rate if
+ desired.
+ To adjust the edge-slowdown, the 'vddmac'
+ must be specified. Table 1 lists the
+ supported edge-slowdown values for a given
+ 'vddmac'.
+ Default value is 0%.
+ Ref: Table:1 - Edge rate change (below).
Table: 1 - Edge rate change
----------------------------------------------------------------|
@@ -29,23 +34,23 @@ Table: 1 - Edge rate change
| |
| 3300 mV 2500 mV 1800 mV 1500 mV |
|---------------------------------------------------------------|
-| Default Deafult Default Default |
+| 0% 0% 0% 0% |
| (Fastest) (recommended) (recommended) |
|---------------------------------------------------------------|
-| -2% -3% -5% -6% |
+| 2% 3% 5% 6% |
|---------------------------------------------------------------|
-| -4% -6% -9% -14% |
+| 4% 6% 9% 14% |
|---------------------------------------------------------------|
-| -7% -10% -16% -21% |
+| 7% 10% 16% 21% |
|(recommended) (recommended) |
|---------------------------------------------------------------|
-| -10% -14% -23% -29% |
+| 10% 14% 23% 29% |
|---------------------------------------------------------------|
-| -17% -23% -35% -42% |
+| 17% 23% 35% 42% |
|---------------------------------------------------------------|
-| -29% -37% -52% -58% |
+| 29% 37% 52% 58% |
|---------------------------------------------------------------|
-| -53% -63% -76% -77% |
+| 53% 63% 76% 77% |
| (slowest) |
|---------------------------------------------------------------|
@@ -54,5 +59,5 @@ Example:
vsc8531_0: ethernet-phy@0 {
compatible = "ethernet-phy-id0007.0570";
vsc8531,vddmac = <3300>;
- vsc8531,edge-slowdown = <21>;
+ vsc8531,edge-slowdown = <7>;
};