Documentation/devicetree/bindings/net/mscc-phy-vsc8531.txt

   1 * Microsemi - vsc8531 Giga bit ethernet phy
   2
   3 Required properties:
   4 - compatible    : Should contain phy id as "ethernet-phy-idAAAA.BBBB"
   5                   The PHY device uses the binding described in
   6                   Documentation/devicetree/bindings/net/phy.txt
   7
   8 Optional properties:
   9 - vsc8531,vddmac        : The vddmac in mV.
  10 - vsc8531,edge-slowdown : % the edge should be slowed down relative to
  11                           the fastest possible edge time. Native sign
  12                           need not enter.
  13                           Edge rate sets the drive strength of the MAC
  14                           interface output signals.  Changing the drive
  15                           strength will affect the edge rate of the output
  16                           signal.  The goal of this setting is to help
  17                           reduce electrical emission (EMI) by being able
  18                           to reprogram drive strength and in effect slow
  19                           down the edge rate if desired.  Table 1 shows the
  20                           impact to the edge rate per VDDMAC supply for each
  21                           drive strength setting.
  22                           Ref: Table:1 - Edge rate change below.
  23
  24 Note: see dt-bindings/net/mscc-phy-vsc8531.h for applicable values
  25
  26 Table: 1 - Edge rate change
  27 ----------------------------------------------------------------|
  28 |               Edge Rate Change (VDDMAC)                       |
  29 |                                                               |
  30 | 3300 mV       2500 mV         1800 mV         1500 mV         |
  31 |---------------------------------------------------------------|
  32 | Default       Deafult         Default         Default         |
  33 | (Fastest)                     (recommended)   (recommended)   |
  34 |---------------------------------------------------------------|
  35 | -2%           -3%             -5%             -6%             |
  36 |---------------------------------------------------------------|
  37 | -4%           -6%             -9%             -14%            |
  38 |---------------------------------------------------------------|
  39 | -7%           -10%            -16%            -21%            |
  40 |(recommended)  (recommended)                                   |
  41 |---------------------------------------------------------------|
  42 | -10%          -14%            -23%            -29%            |
  43 |---------------------------------------------------------------|
  44 | -17%          -23%            -35%            -42%            |
  45 |---------------------------------------------------------------|
  46 | -29%          -37%            -52%            -58%            |
  47 |---------------------------------------------------------------|
  48 | -53%          -63%            -76%            -77%            |
  49 | (slowest)                                                     |
  50 |---------------------------------------------------------------|
  51
  52 Example:
  53
  54         vsc8531_0: ethernet-phy@0 {
  55                 compatible = "ethernet-phy-id0007.0570";
  56                 vsc8531,vddmac          = <3300>;
  57                 vsc8531,edge-slowdown   = <21>;
  58         };