I am a newbie to the embedded linux and device-tree world. I am trying to modify the device tree of ethernet phy from TI. I am interested to know what values the following variables <DP83867_RGMIIDCTL_2_25_NS>, <DP83867_RGMIIDCTL_2_75_NS> and <DP83867_PHYCR_FIFO_DEPTH_4_B_NIB> correspond to. It appears to be delay values, but I searched through the datasheet (https://www.ti.com/lit/ds/symlink/dp83867ir.pdf?HQS=dis-mous-null-mousermode-dsf-pf-null-wwe&DCM=yes&ref_url=https%3A%2F%2Fwww.mouser.co.uk%2F&distId=26) and couldn't find any reference to such variable.
Can someone with some experience in device-tree explain where these variable are coming from and how to change/configure such register values.
&gem3 { /* required by spec */
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_gem3_default>;
phy-handle = <&phy0>;
phy-mode = "rgmii-id";
mdio: mdio {
#address-cells = <1>;
#size-cells = <0>;
reset-gpios = <&gpio 38 GPIO_ACTIVE_LOW>;
reset-delay-us = <2>;
phy0: ethernet-phy@1 {
#phy-cells = <1>;
reg = <1>;
ti,rx-internal-delay = <DP83867_RGMIIDCTL_2_25_NS>;
ti,tx-internal-delay = <DP83867_RGMIIDCTL_2_75_NS>;
ti,fifo-depth = <DP83867_PHYCR_FIFO_DEPTH_4_B_NIB>;
ti,dp83867-rxctrl-strap-quirk;
};
};
};
What does the variable and value of DP83867_RGMIIDCTL_2_25_NS in device tree correspond to?
From https://elixir.bootlin.com/linux/latest/A/ident/DP83867_RGMIIDCTL_2_25_NS it corresponds to a macro with the value 0x8.
#define DP83867_RGMIIDCTL_2_25_NS 0x8