问题现象

        MTK T800平台,内核版本4.19.98,使用两片88Q2110芯片,分别RGMII和SGMII,drive identificationphy id失败：

DTS配置

        88Q2110支持C45和C22访问：

         phy idThe resistors are not soldered,默认地址0：

 C22访问寄存器

         Configuration and driver use by defaultC45访问寄存器,但使用C45读phy id失败,改为C22访问寄存器：

        使用C22way by accessing external registers13和14读写寄存器：

         C45读寄存器：

         I don't understand how it works.

static int get_phy_c45_devs_in_pkg(struct mii_bus *bus, int addr, int dev_addr,
				   u32 *devices_in_package)
{
	int phy_reg, reg_addr;

	reg_addr = MII_ADDR_C45 | dev_addr << 16 | MDIO_DEVS2;
	phy_reg = mdiobus_read(bus, addr, reg_addr);
	if (phy_reg < 0)
		return -EIO;
	*devices_in_package = (phy_reg & 0xffff) << 16;

	reg_addr = MII_ADDR_C45 | dev_addr << 16 | MDIO_DEVS1;
	phy_reg = mdiobus_read(bus, addr, reg_addr);
	if (phy_reg < 0)
		return -EIO;
	*devices_in_package |= (phy_reg & 0xffff);

	return 0;
}

        C22读寄存器：

static int get_phy_c45_devs_in_pkg(struct mii_bus *bus, int addr, int dev_addr,
				   u32 *devices_in_package)
{
	int phy_reg, reg_addr;
	mdiobus_write(bus, addr, 0xd, 0x0001);
	mdiobus_write(bus, addr, 0xe, 0x0002);
	mdiobus_write(bus, addr, 0xd, 0x4001);
	phy_reg = mdiobus_read(bus, addr, 0xe);
	printk("PHY_REG = %x\n",phy_reg);
	if (phy_reg < 0)
		return -EIO;
	*devices_in_package = (phy_reg & 0xffff) << 16;
	mdiobus_write(bus, addr, 0xd, 0x0001);
	mdiobus_write(bus, addr, 0xe, 0x0003);
	mdiobus_write(bus, addr, 0xd, 0x4001);
	phy_reg = mdiobus_read(bus, addr, 0xe);
	if (phy_reg < 0)
		return -EIO;
	*devices_in_package |= (phy_reg & 0xffff);
	printk("phy IDDDD = %x\n",*devices_in_package);

	return 0;
}

步骤：

        mdiobus_write(bus, addr, 0xd, 0x0001);

        1、先写寄存器13（0xd）,写00到bit[15:14]表示00=Address地址功能,写1到bit[4:0]表示设备地址.

        mdiobus_write(bus, addr, 0xe, 0x0002);

        2、后写寄存器14（0xe）,写0x0002到bit[15:0]表示寄存器地址,Represents a read deviceID

         mdiobus_write(bus, addr, 0xd, 0x4001);

         3、写寄存器13（0xd）,写01到[15:14]Indicates the function of reading and writing data from registers,写1到bit[4:0]表示设备地址.

        phy_reg = mdiobus_read(bus, addr, 0xe);

        4、读寄存器14（0xe）,返回寄存器0x0002的数据.

        获取到设备ID数据是0x2B,

         0x0003Register read is yes0x0982,10,011000 ,0010,对应0x02,0x18,0x2.The revision number is 2,This is a one-to-one correspondence.

 寄存器操作命令

   yikeSupport customers to set and read by reading and writing filesPHY寄存器,具体命令格式如下.

   （1）Read the register with the following command：

      echo 协议类型r 寄存器地址 > /sys/devices/platform/11021000.ethernet/stmmac

      例如：通过clause22Protocol read registers0x1：

      echo cl22r 1 > /sys/devices/platform/soc/1101a000.eth/stmmac

    （2）Write the register by the following command：

     echo 协议类型w 寄存器地址 value > /sys/devices/platform/11021000.ethernet/stmmac

     例如：通过clause22Protocol write register0x0值为0x5040

      echo cl22w 0 0x5040 > /sys/devices/platform/11021000.ethernet/stmmac

以realtek8211F PHY为例,

（1）设置phy为loopback模式：

echo cl22r 0 > /sys/devices/platform/11021000.ethernet/stmmac (读出 PHY register0的值)

echo cl45r 1 0x834  > /sys/devices/platform/11021000.ethernet/stmmac（c45读方式）

echo cl22w 0 xxx > /sys/devices/platform/11021000.ethernet/stmmac (xxx:为上一步register0读出的值,将bit14置1the hexadecimal value after)

echo cl45w 1 0x834 0x8001 > /sys/devices/platform/11021000.ethernet/stmmac

（2）复位phy,进行reset：

echo cl22r 0 > /sys/devices/platform/11021000.ethernet/stmmac (读出 PHY register0的值)

echo cl22w 0 0x9040> /sys/devices/platform/11021000.ethernet/stmmac (xxx:为上一步register0读出的值,将bit15置1the hexadecimal value after)

疑问：为何T800使用C45I can't read itID呢？