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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
assume clause 22.
If the phy's identifier is known then the list may contain an entry
of the form: "ethernet-phy-idAAAA.BBBB" where
If the PHY reports an incorrect ID (or none at all) then the
"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
4 hex digits. This is the chip vendor OUI bits 3:18
BBBB - The value of the 16 bit Phy Identifier 2 register as