diff options
Diffstat (limited to 'Documentation/devicetree/bindings/net/mscc-phy-vsc8531.txt')
| -rw-r--r-- | Documentation/devicetree/bindings/net/mscc-phy-vsc8531.txt | 51 |
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>; }; |