[PATCH] Documentation: net: phy: improve explanation when to specify the PHY ID
From: Martin Blumenstingl <hidden>
Date: 2017-01-22 16:41:32
Also in:
linux-devicetree
Subsystem:
networking drivers, open firmware and flattened device tree bindings, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Linus Torvalds
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-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org> --- Thanks to Andrew Lunn for pointing the documentation issue out to me in: http://lists.infradead.org/pipermail/linux-amlogic/2017-January/002141.html Documentation/devicetree/bindings/net/phy.txt | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/Documentation/devicetree/bindings/net/phy.txt b/Documentation/devicetree/bindings/net/phy.txt
index ff1bc4b1bb3b..fb5056b22685 100644
--- a/Documentation/devicetree/bindings/net/phy.txt
+++ b/Documentation/devicetree/bindings/net/phy.txt@@ -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
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2.11.0
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