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net: phy: Cleanup the Edge-Rate feature in Microsemi PHYs.

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Edge-Rate cleanup include the following:
- Updated device tree bindings documentation for edge-rate
- The edge-rate is now specified as a "slowdown", meaning that it is now
  being specified as positive values instead of negative (both
  documentation and implementation wise).
- Only explicitly documented values for "vsc8531,vddmac" and
  "vsc8531,edge-slowdown" are accepted by the device driver.
- Deleted include/dt-bindings/net/mscc-phy-vsc8531.h as it was not needed.
- Read/validate devicetree settings in probe instead of init

Signed-off-by: Allan W. Nielsen <allan.nielsen@microsemi.com>
Signed-off-by: Raju Lakkaraju <raju.lakkaraju@microsemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Allan W. Nielsen
2016-10-12 15:47:51 +02:00
committed by David S. Miller
parent cf53b1da73
commit 4f58e6dceb
3 changed files with 92 additions and 119 deletions
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51
Documentation/devicetree/bindings/net/mscc-phy-vsc8531.txt
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@@ -6,22 +6,27 @@ Required properties:
Documentation/devicetree/bindings/net/phy.txt
Optional properties:
- vsc8531,vddmac : The vddmac in mV.
- vsc8531,vddmac : The vddmac in mV. Allowed values is listed
in the first row of Table 1 (below).
This property is only used in combination
with the 'edge-slowdown' property.
Default value is 3300.
- vsc8531,edge-slowdown : % the edge should be slowed down relative to
the fastest possible edge time. Native sign
need not enter.
the fastest possible edge time.
Edge rate sets the drive strength of the MAC
interface output signals. Changing the drive
strength will affect the edge rate of the output
signal. The goal of this setting is to help
reduce electrical emission (EMI) by being able
to reprogram drive strength and in effect slow
down the edge rate if desired. Table 1 shows the
impact to the edge rate per VDDMAC supply for each
drive strength setting.
Ref: Table:1 - Edge rate change below.
Note: see dt-bindings/net/mscc-phy-vsc8531.h for applicable values
interface output signals. Changing the
drive strength will affect the edge rate of
the output signal. The goal of this setting
is to help reduce electrical emission (EMI)
by being able to reprogram drive strength
and in effect slow down the edge rate if
desired.
To adjust the edge-slowdown, the 'vddmac'
must be specified. Table 1 lists the
supported edge-slowdown values for a given
'vddmac'.
Default value is 0%.
Ref: Table:1 - Edge rate change (below).
Table: 1 - Edge rate change
----------------------------------------------------------------|
@@ -29,23 +34,23 @@ Table: 1 - Edge rate change
| |
| 3300 mV 2500 mV 1800 mV 1500 mV |
|---------------------------------------------------------------|
| Default Deafult Default Default |
| 0% 0% 0% 0% |
| (Fastest) (recommended) (recommended) |
|---------------------------------------------------------------|
| -2% -3% -5% -6% |
| 2% 3% 5% 6% |
|---------------------------------------------------------------|
| -4% -6% -9% -14% |
| 4% 6% 9% 14% |
|---------------------------------------------------------------|
| -7% -10% -16% -21% |
| 7% 10% 16% 21% |
|(recommended) (recommended) |
|---------------------------------------------------------------|
| -10% -14% -23% -29% |
| 10% 14% 23% 29% |
|---------------------------------------------------------------|
| -17% -23% -35% -42% |
| 17% 23% 35% 42% |
|---------------------------------------------------------------|
| -29% -37% -52% -58% |
| 29% 37% 52% 58% |
|---------------------------------------------------------------|
| -53% -63% -76% -77% |
| 53% 63% 76% 77% |
| (slowest) |
|---------------------------------------------------------------|
@@ -54,5 +59,5 @@ Example:
vsc8531_0: ethernet-phy@0 {
compatible = "ethernet-phy-id0007.0570";
vsc8531,vddmac = <3300>;
vsc8531,edge-slowdown = <21>;
vsc8531,edge-slowdown = <7>;
};