f3c2caacee
Currently a MDIO bus is created if the devicetree description is either:
1. Not fixed-link
2. fixed-link but contains a MDIO bus as well
The "1" case above isn't always accurate. If there's a phy-handle,
it could be referencing a phy on another MDIO controller's bus[1]. In
this case, where the MDIO bus is not described at all, currently
stmmac will make a MDIO bus and scan its address space to discover
phys (of which there are none). This process takes time scanning a bus
that is known to be empty, delaying time to complete probe.
There are also a lot of upstream devicetrees[2] that expect a MDIO bus
to be created, scanned for phys, and the first one found connected
to the MAC. This case can be inferred from the platform description by
not having a phy-handle && not being fixed-link. This hits case "1" in
the current driver's logic, and must be handled in any logic change here
since it is a valid legacy dt-binding.
Let's improve the logic to create a MDIO bus if either:
- Devicetree contains a MDIO bus
- !fixed-link && !phy-handle (legacy handling)
This way the case where no MDIO bus should be made is handled, as well
as retaining backwards compatibility with the valid cases.
Below devicetree snippets can be found that explain some of
the cases above more concretely.
Here's[0] a devicetree example where the MAC is both fixed-link and
driving a switch on MDIO (case "2" above). This needs a MDIO bus to
be created:
&fec1 {
phy-mode = "rmii";
fixed-link {
speed = <100>;
full-duplex;
};
mdio1: mdio {
switch0: switch0@0 {
compatible = "marvell,mv88e6190";
pinctrl-0 = <&pinctrl_gpio_switch0>;
};
};
};
Here's[1] an example where there is no MDIO bus or fixed-link for
the ethernet1 MAC, so no MDIO bus should be created since ethernet0
is the MDIO master for ethernet1's phy:
ðernet0 {
phy-mode = "sgmii";
phy-handle = <&sgmii_phy0>;
mdio {
compatible = "snps,dwmac-mdio";
sgmii_phy0: phy@8 {
compatible = "ethernet-phy-id0141.0dd4";
reg = <0x8>;
device_type = "ethernet-phy";
};
sgmii_phy1: phy@a {
compatible = "ethernet-phy-id0141.0dd4";
reg = <0xa>;
device_type = "ethernet-phy";
};
};
};
ðernet1 {
phy-mode = "sgmii";
phy-handle = <&sgmii_phy1>;
};
Finally there's descriptions like this[2] which don't describe the
MDIO bus but expect it to be created and the whole address space
scanned for a phy since there's no phy-handle or fixed-link described:
&gmac {
phy-supply = <&vcc_lan>;
phy-mode = "rmii";
snps,reset-gpio = <&gpio3 RK_PB4 GPIO_ACTIVE_HIGH>;
snps,reset-active-low;
snps,reset-delays-us = <0 10000 1000000>;
};
[0] https://elixir.bootlin.com/linux/v6.5-rc5/source/arch/arm/boot/dts/nxp/vf/vf610-zii-ssmb-dtu.dts
[1] https://elixir.bootlin.com/linux/v6.6-rc5/source/arch/arm64/boot/dts/qcom/sa8775p-ride.dts
[2] https://elixir.bootlin.com/linux/v6.6-rc5/source/arch/arm64/boot/dts/rockchip/rk3368-r88.dts#L164
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>
Co-developed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Andrew Halaney <ahalaney@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.