设备树，更改固定链接以太网phy速度运行时 [英] device tree, change fixed link ethernet phy speed runtime

问题描述

我正在使用具有Linux内核不支持的phy的自定义IMX8板(这是第45条汽车oabr收发器).

I'm working with a custom IMX8 board with a phy that is not supported by the Linux kernel (it's a clause 45 automotive oabr transceiver).

该phy实际上正在运行，其mdio总线和数字IO由一个用户空间应用程序控制.

The phy is actually working, and its mdio bus and digital IO's are controlled with an userspace application.

要达到这个目的，我必须将它与设备树绑定在一起，如下所示具有fixed-link属性.

To acheive this i had to bind it in the device tree with the fixed-link property as below.

...
port@0 {
                        reg = <0x00>;
                        label = "oabr";
                        phy-mode = "rgmii";

                        fixed-link {
                            speed = <1000>;
                            full-duplex;
                            pause;
                            asym-pause;
                        };
                    };
...

现在...问题是，我想将phy的速度从1000更改为100，如果能够配置phy并更改设备树，则可以执行此操作，但这意味着需要重新启动设备来加载新的dts文件.

Now... the question is, i would like to change the speed of the phy from 1000 to 100, i'm able to do it if configure the phy AND change the device tree, but this implies a reboot of the device to load a new dts file.

有没有一种方法可以使其在运行时正常运行?

Is there a way to get it working runtime?

非常感谢

马可

推荐答案

为了在运行时添加或加载设备树blob，唯一的方法是使用Linux

In order to add or load a device tree blob in runtime, the only way is to use Linux overlay.

但是问题是NXP在其linux-imx内核中不支持它，您可以在

But the problem is that NXP does not support it in its linux-imx kernel , you can see their post about it here.

如果您没有永久更改用于映像的主设备树文件，我可以建议您这样做:

If you don't make the change permanently to your main device tree file used for the image, I can advise you of doing this:

1. 创建另一个包含主要dts的dts(例如:new-phy.dts)，并在其中添加您的替代节点

1. Create another dts (Ex: new-phy.dts) that includes the main dts and add your override node there

将新的dtb名称添加到您的 $ {MACHINE} .conf KERNEL_DEVICETREE 变量:

Add the new dtb name to your ${MACHINE}.conf KERNEL_DEVICETREE variable:

KERNEL_DEVICETREE + ="freescale/new-phy.dtb"

现在，从u-boot CLI引导后，您需要选择它，例如:

Now you need to choose it once you boot from u-boot CLI, like:

u-boot> setenv fdt_file new-phy.dtb

u-boot> setenv fdt_file new-phy.dtb

u-boot> saveenv

u-boot> saveenv

u-boot>启动

u-boot> boot

或者，您可以在u-boot/configs/$ {MACHINE} _defconfig中进行设置:

Or, you can set it in your u-boot/configs/${MACHINE}_defconfig:

CONFIG_DEFAULT_FDT_FILE ="new-phy.dtb"

否则，您可以尝试为正在使用的内核添加对覆盖的支持.

Otherwise, you can try to add the overlay support for the kernel you are using.

Toradex具有基于IMX8M的SOM和EVK，它们正在使用叠加层，您可以看一下此处，并尝试了解他们为支持该网站所做的工作.

Toradex has SOMs and EVKs based on IMX8M and they are working with overlays, you can take a look here and try to understand what they did to support it.

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