Modifying binding or duplicating compatible string
From: Rafał Miłecki <hidden>
Date: 2017-05-09 10:09:00
Hi,
We currently have a "brcm,ns-ax-usb3-phy" binding defined for Broadcom's USB
3.0 PHY which you can find in:
Documentation/devicetree/bindings/phy/bcm-ns-usb3-phy.txt
It looks like this:
usb3-phy {
compatible = "brcm,ns-ax-usb3-phy";
reg = <0x18003000 0x1000>, <0x18105000 0x1000>;
reg-names = "ccb-mii", "dmp";
#phy-cells = <0>;
};
The problem is that PHY is actually attached to the MDIO bus and 0x18003000
+ 0x18003004 registers are used to access whole MDIO, not just this single
PHY.
A correct binding should look like this:
mdio: mdio@18003000 {
compatible = "brcm,iproc-mdio";
reg = <0x18003000 0x8>;
#size-cells = <1>;
#address-cells = <0>;
usb3-phy@10 {
compatible = "brcm,ns-ax-usb3-phy";
reg = <0x10>;
usb3-dmp-syscon = <&usb3_dmp>;
#phy-cells = <0>;
};
};
usb3_dmp: syscon@18105000 {
reg = <0x18105000 0x1000>;
};
I mean to clean up this situation. My question is: is this acceptable to
support the same compatible string in two contexts?
1) For backward compatibility the first one would require specifying both:
ccb-mii / MDIO register and DMP register.
2) For cleaniness the new one would require reg to be PHY index and DMP one
to be specified with usb3-dmp-syscon.
In Linux there shouldn't be a problem as MDIO children nodes are handled
separately, but I still don't know if it's an acceptable solution.
Can I have some opinions on this, please?
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