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

   1 * Microsemi - vsc8531 Giga bit ethernet phy
   2
   3 Optional properties:
   4 - vsc8531,vddmac        : The vddmac in mV. Allowed values is listed
   5                           in the first row of Table 1 (below).
   6                           This property is only used in combination
   7                           with the 'edge-slowdown' property.
   8                           Default value is 3300.
   9 - vsc8531,edge-slowdown : % the edge should be slowed down relative to
  10                           the fastest possible edge time.
  11                           Edge rate sets the drive strength of the MAC
  12                           interface output signals.  Changing the
  13                           drive strength will affect the edge rate of
  14                           the output signal.  The goal of this setting
  15                           is to help reduce electrical emission (EMI)
  16                           by being able to reprogram drive strength
  17                           and in effect slow down the edge rate if
  18                           desired.
  19                           To adjust the edge-slowdown, the 'vddmac'
  20                           must be specified. Table 1 lists the
  21                           supported edge-slowdown values for a given
  22                           'vddmac'.
  23                           Default value is 0%.
  24                           Ref: Table:1 - Edge rate change (below).
  25 - vsc8531,led-[N]-mode  : LED mode. Specify how the LED[N] should behave.
  26                           N depends on the number of LEDs supported by a
  27                           PHY.
  28                           Allowed values are defined in
  29                           "include/dt-bindings/net/mscc-phy-vsc8531.h".
  30                           Default values are VSC8531_LINK_1000_ACTIVITY (1),
  31                           VSC8531_LINK_100_ACTIVITY (2),
  32                           VSC8531_LINK_ACTIVITY (0) and
  33                           VSC8531_DUPLEX_COLLISION (8).
  34
  35
  36 Table: 1 - Edge rate change
  37 ----------------------------------------------------------------|
  38 |               Edge Rate Change (VDDMAC)                       |
  39 |                                                               |
  40 | 3300 mV       2500 mV         1800 mV         1500 mV         |
  41 |---------------------------------------------------------------|
  42 | 0%            0%              0%              0%              |
  43 | (Fastest)                     (recommended)   (recommended)   |
  44 |---------------------------------------------------------------|
  45 | 2%            3%              5%              6%              |
  46 |---------------------------------------------------------------|
  47 | 4%            6%              9%              14%             |
  48 |---------------------------------------------------------------|
  49 | 7%            10%             16%             21%             |
  50 |(recommended)  (recommended)                                   |
  51 |---------------------------------------------------------------|
  52 | 10%           14%             23%             29%             |
  53 |---------------------------------------------------------------|
  54 | 17%           23%             35%             42%             |
  55 |---------------------------------------------------------------|
  56 | 29%           37%             52%             58%             |
  57 |---------------------------------------------------------------|
  58 | 53%           63%             76%             77%             |
  59 | (slowest)                                                     |
  60 |---------------------------------------------------------------|
  61
  62 Example:
  63
  64         vsc8531_0: ethernet-phy@0 {
  65                 compatible = "ethernet-phy-id0007.0570";
  66                 vsc8531,vddmac          = <3300>;
  67                 vsc8531,edge-slowdown   = <7>;
  68                 vsc8531,led-0-mode      = <LINK_1000_ACTIVITY>;
  69                 vsc8531,led-1-mode      = <LINK_100_ACTIVITY>;
  70         };