android-kvm / linux / eb6a9339efeb6f3d2b5c86fdf2382cdc293eca2c / . / 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. | |

The KSZ9031 hardware supports a range of skew values from negative to | |

positive, where the specific range is property dependent. All values | |

specified in the devicetree are offset by the minimum value so they | |

can be represented as positive integers in the devicetree since it's | |

difficult to represent a negative number in the devictree. | |

The following 5-bit values table apply to rxc-skew-ps and txc-skew-ps. | |

Pad Skew Value Delay (ps) Devicetree Value | |

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

0_0000 -900ps 0 | |

0_0001 -840ps 60 | |

0_0010 -780ps 120 | |

0_0011 -720ps 180 | |

0_0100 -660ps 240 | |

0_0101 -600ps 300 | |

0_0110 -540ps 360 | |

0_0111 -480ps 420 | |

0_1000 -420ps 480 | |

0_1001 -360ps 540 | |

0_1010 -300ps 600 | |

0_1011 -240ps 660 | |

0_1100 -180ps 720 | |

0_1101 -120ps 780 | |

0_1110 -60ps 840 | |

0_1111 0ps 900 | |

1_0000 60ps 960 | |

1_0001 120ps 1020 | |

1_0010 180ps 1080 | |

1_0011 240ps 1140 | |

1_0100 300ps 1200 | |

1_0101 360ps 1260 | |

1_0110 420ps 1320 | |

1_0111 480ps 1380 | |

1_1000 540ps 1440 | |

1_1001 600ps 1500 | |

1_1010 660ps 1560 | |

1_1011 720ps 1620 | |

1_1100 780ps 1680 | |

1_1101 840ps 1740 | |

1_1110 900ps 1800 | |

1_1111 960ps 1860 | |

The following 4-bit values table apply to the txdX-skew-ps, rxdX-skew-ps | |

data pads, and the rxdv-skew-ps, txen-skew-ps control pads. | |

Pad Skew Value Delay (ps) Devicetree Value | |

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

0000 -420ps 0 | |

0001 -360ps 60 | |

0010 -300ps 120 | |

0011 -240ps 180 | |

0100 -180ps 240 | |

0101 -120ps 300 | |

0110 -60ps 360 | |

0111 0ps 420 | |

1000 60ps 480 | |

1001 120ps 540 | |

1010 180ps 600 | |

1011 240ps 660 | |

1100 300ps 720 | |

1101 360ps 780 | |

1110 420ps 840 | |

1111 480ps 900 | |

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: | |

LAN8841: | |

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: | |

/* Attach to an Ethernet device with autodetected PHY */ | |

&enet { | |

rxc-skew-ps = <1800>; | |

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

txc-skew-ps = <1800>; | |

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

status = "okay"; | |

}; | |

/* Attach to an explicitly-specified PHY */ | |

mdio { | |

phy0: ethernet-phy@0 { | |

rxc-skew-ps = <1800>; | |

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

txc-skew-ps = <1800>; | |

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

reg = <0>; | |

}; | |

}; | |

ethernet@70000 { | |

phy = <&phy0>; | |

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

}; | |

References | |

Micrel ksz9021rl/rn Data Sheet, Revision 1.2. Dated 2/13/2014. | |

http://www.micrel.com/_PDF/Ethernet/datasheets/ksz9021rl-rn_ds.pdf | |

Micrel ksz9031rnx Data Sheet, Revision 2.1. Dated 11/20/2014. | |

http://www.micrel.com/_PDF/Ethernet/datasheets/KSZ9031RNX.pdf | |

Notes: | |

Note that a previous version of the Micrel ksz9021rl/rn Data Sheet | |

was missing extended register 106 (transmit data pad skews), and | |

incorrectly specified the ps per step as 200ps/step instead of | |

120ps/step. The latest update to this document reflects the latest | |

revision of the Micrel specification even though usage in the kernel | |

still reflects that incorrect document. |