code / linux / torvalds / linux / 9b3a713feef8db41d4bcccb3b97e86ee906690c8 / . / Documentation / devicetree / bindings / net / micrel-ksz90x1.txt

Micrel KSZ9021/KSZ9031/KSZ9131 Gigabit Ethernet PHY | |

Some boards require special tuning values, particularly when it comes | |

to clock delays. You can specify clock delay values in the PHY OF | |

device node. Deprecated, but still supported, these properties can | |

also be added to an Ethernet OF device node. | |

Note that these settings are applied after any phy-specific fixup from | |

phy_fixup_list (see phy_init_hw() from drivers/net/phy/phy_device.c), | |

and therefore may overwrite them. | |

KSZ9021: | |

All skew control options are specified in picoseconds. The minimum | |

value is 0, the maximum value is 3000, and it can be specified in 200ps | |

steps, *but* these values are in not fact what you get because this chip's | |

skew values actually increase in 120ps steps, starting from -840ps. The | |

incorrect values came from an error in the original KSZ9021 datasheet | |

before it was corrected in revision 1.2 (Feb 2014), but it is too late to | |

change the driver now because of the many existing device trees that have | |

been created using values that go up in increments of 200. | |

The following table shows the actual skew delay you will get for each of the | |

possible devicetree values, and the number that will be programmed into the | |

corresponding pad skew register: | |

Device Tree Value Delay Pad Skew Register Value | |

----------------------------------------------------- | |

0 -840ps 0000 | |

200 -720ps 0001 | |

400 -600ps 0010 | |

600 -480ps 0011 | |

800 -360ps 0100 | |

1000 -240ps 0101 | |

1200 -120ps 0110 | |

1400 0ps 0111 | |

1600 120ps 1000 | |

1800 240ps 1001 | |

2000 360ps 1010 | |

2200 480ps 1011 | |

2400 600ps 1100 | |

2600 720ps 1101 | |

2800 840ps 1110 | |

3000 960ps 1111 | |

Optional properties: | |

- rxc-skew-ps : Skew control of RXC pad | |

- rxdv-skew-ps : Skew control of RX CTL pad | |

- txc-skew-ps : Skew control of TXC pad | |

- txen-skew-ps : Skew control of TX CTL pad | |

- rxd0-skew-ps : Skew control of RX data 0 pad | |

- rxd1-skew-ps : Skew control of RX data 1 pad | |

- rxd2-skew-ps : Skew control of RX data 2 pad | |

- rxd3-skew-ps : Skew control of RX data 3 pad | |

- txd0-skew-ps : Skew control of TX data 0 pad | |

- txd1-skew-ps : Skew control of TX data 1 pad | |

- txd2-skew-ps : Skew control of TX data 2 pad | |

- txd3-skew-ps : Skew control of TX data 3 pad | |

KSZ9031: | |

All skew control options are specified in picoseconds. The minimum | |

value is 0, and the maximum is property-dependent. The increment | |

step is 60ps. The default value is the neutral setting, so setting | |

rxc-skew-ps=<0> actually results in -900 picoseconds adjustment. | |

Optional properties: | |

Maximum value of 1860, default value 900: | |

- rxc-skew-ps : Skew control of RX clock pad | |

- txc-skew-ps : Skew control of TX clock pad | |

Maximum value of 900, default value 420: | |

- rxdv-skew-ps : Skew control of RX CTL pad | |

- txen-skew-ps : Skew control of TX CTL pad | |

- rxd0-skew-ps : Skew control of RX data 0 pad | |

- rxd1-skew-ps : Skew control of RX data 1 pad | |

- rxd2-skew-ps : Skew control of RX data 2 pad | |

- rxd3-skew-ps : Skew control of RX data 3 pad | |

- txd0-skew-ps : Skew control of TX data 0 pad | |

- txd1-skew-ps : Skew control of TX data 1 pad | |

- txd2-skew-ps : Skew control of TX data 2 pad | |

- txd3-skew-ps : Skew control of TX data 3 pad | |

- micrel,force-master: | |

Boolean, force phy to master mode. Only set this option if the phy | |

reference clock provided at CLK125_NDO pin is used as MAC reference | |

clock because the clock jitter in slave mode is to high (errata#2). | |

Attention: The link partner must be configurable as slave otherwise | |

no link will be established. | |

KSZ9131: | |

All skew control options are specified in picoseconds. The increment | |

step is 100ps. Unlike KSZ9031, the values represent picoseccond delays. | |

A negative value can be assigned as rxc-skew-psec = <(-100)>;. | |

Optional properties: | |

Range of the value -700 to 2400, default value 0: | |

- rxc-skew-psec : Skew control of RX clock pad | |

- txc-skew-psec : Skew control of TX clock pad | |

Range of the value -700 to 800, default value 0: | |

- rxdv-skew-psec : Skew control of RX CTL pad | |

- txen-skew-psec : Skew control of TX CTL pad | |

- rxd0-skew-psec : Skew control of RX data 0 pad | |

- rxd1-skew-psec : Skew control of RX data 1 pad | |

- rxd2-skew-psec : Skew control of RX data 2 pad | |

- rxd3-skew-psec : Skew control of RX data 3 pad | |

- txd0-skew-psec : Skew control of TX data 0 pad | |

- txd1-skew-psec : Skew control of TX data 1 pad | |

- txd2-skew-psec : Skew control of TX data 2 pad | |

- txd3-skew-psec : Skew control of TX data 3 pad | |

Examples: | |

mdio { | |

phy0: ethernet-phy@0 { | |

rxc-skew-ps = <3000>; | |

rxdv-skew-ps = <0>; | |

txc-skew-ps = <3000>; | |

txen-skew-ps = <0>; | |

reg = <0>; | |

}; | |

}; | |

ethernet@70000 { | |

phy = <&phy0>; | |

phy-mode = "rgmii-id"; | |

}; |