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. Allowed values is listed
  10                           in the first row of Table 1 (below).
  11                           This property is only used in combination
  12                           with the 'edge-slowdown' property.
  13                           Default value is 3300.
  14 - vsc8531,edge-slowdown : % the edge should be slowed down relative to
  15                           the fastest possible edge time.
  16                           Edge rate sets the drive strength of the MAC
  17                           interface output signals.  Changing the
  18                           drive strength will affect the edge rate of
  19                           the output signal.  The goal of this setting
  20                           is to help reduce electrical emission (EMI)
  21                           by being able to reprogram drive strength
  22                           and in effect slow down the edge rate if
  23                           desired.
  24                           To adjust the edge-slowdown, the 'vddmac'
  25                           must be specified. Table 1 lists the
  26                           supported edge-slowdown values for a given
  27                           'vddmac'.
  28                           Default value is 0%.
  29                           Ref: Table:1 - Edge rate change (below).
  30
  31 Table: 1 - Edge rate change
  32 ----------------------------------------------------------------|
  33 |               Edge Rate Change (VDDMAC)                       |
  34 |                                                               |
  35 | 3300 mV       2500 mV         1800 mV         1500 mV         |
  36 |---------------------------------------------------------------|
  37 | 0%            0%              0%              0%              |
  38 | (Fastest)                     (recommended)   (recommended)   |
  39 |---------------------------------------------------------------|
  40 | 2%            3%              5%              6%              |
  41 |---------------------------------------------------------------|
  42 | 4%            6%              9%              14%             |
  43 |---------------------------------------------------------------|
  44 | 7%            10%             16%             21%             |
  45 |(recommended)  (recommended)                                   |
  46 |---------------------------------------------------------------|
  47 | 10%           14%             23%             29%             |
  48 |---------------------------------------------------------------|
  49 | 17%           23%             35%             42%             |
  50 |---------------------------------------------------------------|
  51 | 29%           37%             52%             58%             |
  52 |---------------------------------------------------------------|
  53 | 53%           63%             76%             77%             |
  54 | (slowest)                                                     |
  55 |---------------------------------------------------------------|
  56
  57 Example:
  58
  59         vsc8531_0: ethernet-phy@0 {
  60                 compatible = "ethernet-phy-id0007.0570";
  61                 vsc8531,vddmac          = <3300>;
  62                 vsc8531,edge-slowdown   = <7>;
  63         };