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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 | 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: 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. |