From: Dinh Nguyen <dinguyen@xxxxxxxxxxxxxxxxxxxxx>
Update the Micrel phy documentation for the KSZ9031 PHY to represent how
the actual values are calculated from the code.
Signed-off-by: Dinh Nguyen <dinguyen@xxxxxxxxxxxxxxxxxxxxx>
---
.../devicetree/bindings/net/micrel-ksz90x1.txt | 73 ++++++++++++++++++++++
1 file changed, 73 insertions(+)
diff --git a/Documentation/devicetree/bindings/net/micrel-ksz90x1.txt b/Documentation/devicetree/bindings/net/micrel-ksz90x1.txt
index f9c32ad..9535b2b 100644
--- a/Documentation/devicetree/bindings/net/micrel-ksz90x1.txt
+++ b/Documentation/devicetree/bindings/net/micrel-ksz90x1.txt
@@ -36,6 +36,71 @@ KSZ9031:
value is 0, and the maximum is property-dependent. The increment
step is 60ps.
+ 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:
@@ -72,3 +137,11 @@ Examples:
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
--
2.6.2
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