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Documentation: net: phy: improve explanation when to specify the PHY ID

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The old description basically read like "ethernet-phy-idAAAA.BBBB" can
be specified when you know the actual PHY ID. However, specifying this
has a side-effect: it forces Linux to bind to a certain PHY driver (the
one that matches the ID given in the compatible string), ignoring the ID
which is reported by the actual PHY.
Whenever a device is shipped with (multiple) different PHYs during it's
production lifetime then explicitly specifying
"ethernet-phy-idAAAA.BBBB" could break certain revisions of that device.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Martin Blumenstingl 2017-01-22 17:41:32 +01:00 committed by David S. Miller
parent f39aac7e83
commit 7630ea4bda
1 changed files with 3 additions and 2 deletions
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5
Documentation/devicetree/bindings/net/phy.txt
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@ -19,8 +19,9 @@ Optional Properties:
specifications. If neither of these are specified, the default is to specifications. If neither of these are specified, the default is to
assume clause 22. assume clause 22.
If the phy's identifier is known then the list may contain an entry If the PHY reports an incorrect ID (or none at all) then the
of the form: "ethernet-phy-idAAAA.BBBB" where "compatible" list may contain an entry with the correct PHY ID in the
form: "ethernet-phy-idAAAA.BBBB" where
AAAA - The value of the 16 bit Phy Identifier 1 register as AAAA - The value of the 16 bit Phy Identifier 1 register as
4 hex digits. This is the chip vendor OUI bits 3:18 4 hex digits. This is the chip vendor OUI bits 3:18
BBBB - The value of the 16 bit Phy Identifier 2 register as BBBB - The value of the 16 bit Phy Identifier 2 register as