topic IMX6Q RMII interface KSZ8895RQXCA in i.MX Processors

IMX6Q RMII interface KSZ8895RQXCA

linwangzhao — Tue, 22 May 2018 01:20:12 GMT

IMX6Q使用RMII接口与交换机KSZ8895RQXCA相连时，使用GPIO_16作为ENET_REF_CLK。如何配置MX6QDL_PAD_GPIO_16__ENET_REF_CLK的工作模式为输出50Mhz。使用默认的配置时输出的是125Mhz，参考“Hardware Development Guide for i.MX 6Quad, 6Dual, 6DualLite,6Solo Families of Applications Processors”文档中的“11.4.1 Using the GPIO_16 pin to generate the reference clock”，需要将“ Bits 1–0 of CCM_ANALOG_PLL_ENETn control the frequency fed to the Ethernet MAC and should be set to 01b to obtain 50 MHZ”，如何在设备树中配置CCM_ANALOG_PLL_ENETn 寄存器？使用的内核版本是linux4.1.15，附件为“Hardware Development Guide for i.MX 6Quad, 6Dual, 6DualLite,6Solo Families of Applications Processors”文档。

Re: IMX6Q RMII interface KSZ8895RQXCA

igorpadykov — Tue, 22 May 2018 08:39:54 GMT

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When the IMX6Q is connected to the switch KSZ8895RQXCA using the RMII interface, GPIO_16 is used as ENET_REF_CLK. How to configure the working mode of MX6QDL_PAD_GPIO_16__ENET_REF_CLK to output 50Mhz. When the default configuration is used, 125Mhz is output. Refer to "11.4.1 Using the GPIO_16 pin to generate the reference clock" in the "Hardware Development Guide for i.MX 6Quad, 6Dual, 6DualLite, 6Solo Families of Applications Processors" document. To "Bits 1–0 of CCM_ANALOG_PLL_ENETn control the frequency fed to the Ethernet MAC and should be set to 01b to obtain 50 MHZ", how to configure the CCM_ANALOG_PLL_ENETn register in the device tree? The kernel version used is linux4.1.15 and the attached document is "Hardware Development Guide for i.MX 6Quad, 6Dual, 6DualLite, 6Solo Families of Applications Processors".

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Hi Lee

enet clocks are configured in uboot, not in linux device tree, example can be found in

uboot/board/freescale/mx6slevk/mx6slevk.c, please check function setup_fec()

uboot-imx.git - Freescale i.MX u-boot Tree

Best regards
igor
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Re: IMX6Q RMII interface KSZ8895RQXCA

linwangzhao — Wed, 23 May 2018 11:35:11 GMT

Hi igorpadykov，

通过这个方法可以产生50Mhz的时钟，但还需要注释掉clk_imx6q.c中第915行：

/*Set enet_ref clock to 125M to supply for RGMII tx_clk */
// clk_set_rate(clk[IMX6QDL_CLK_ENET_REF], 125000000);

Re: IMX6Q RMII interface KSZ8895RQXCA

linwangzhao — Wed, 23 May 2018 11:38:04 GMT

igorpadykov

Hi igorpadykov,

我现在遇到另外一个问题，IMX6Q通过RMII接口与以太网交换机芯片KSZ8895RQXCA相连，设备树中关于网络的配置如下：

&fec {
      pinctrl-names = "default";
      pinctrl-0 = <&pinctrl_enet>;
      phy-mode = "rmii";
      phy-reset-gpios = <&gpio1 18 0>;
      fsl,magic-packet;
      status = "okay";
      fixed-link {
         speed = <100>;
         full-duplex;
         pause;
      };
};

pinctrl_enet: enetgrp {
fsl,pins = <
MX6QDL_PAD_ENET_MDIO__ENET_MDIO 0x1b0b0
MX6QDL_PAD_ENET_MDC__ENET_MDC 0x1b0b0
MX6QDL_PAD_ENET_TX_EN__ENET_TX_EN 0x1b0b0
MX6QDL_PAD_ENET_TXD0__ENET_TX_DATA0 0x1b018
MX6QDL_PAD_ENET_TXD1__ENET_TX_DATA1 0x1b018
MX6QDL_PAD_ENET_RX_ER__ENET_RX_ER 0x1b0b0
MX6QDL_PAD_ENET_RXD0__ENET_RX_DATA0 0x1b018
MX6QDL_PAD_ENET_RXD1__ENET_RX_DATA1 0x1b018
MX6QDL_PAD_GPIO_16__ENET_REF_CLK 0x4001b0a8
MX6QDL_PAD_ENET_CRS_DV__ENET_RX_EN 0x1b0b0
>;
};

目前：imx6q(192.168.1.4)无法ping通同一网段内的我的电脑(192.168.1.2)，我的电脑也无法ping通imx6q。通过示波器可以看到imx6q上的TX0/TX1/RX0/RX1都有信号，而且MX6QDL_PAD_GPIO_16__ENET_REF_CLK上有50Mhz的信号。在我的电脑端使用Wireshark抓包工具可以看到imx6q发送的数据包，而且此时我的电脑也响应了该数据包，但是imx6q端没有接收到数据包，也可能是接收的是错误的数据包。

1、使用imx6q(192.168.1.4)ping我的电脑(192.168.1.2)的信息如下：

      root@imx6qsabresd:~# ping 192.168.1.2
      PING 192.168.1.2 (192.168.1.2) 56(84) bytes of data.
      From 192.168.1.4 icmp_seq=1 Destination Host Unreachable
      From 192.168.1.4 icmp_seq=2 Destination Host Unreachable
      From 192.168.1.4 icmp_seq=3 Destination Host Unreachable
      From 192.168.1.4 icmp_seq=4 Destination Host Unreachable

2、使用 ifconfig eth0命令查看的信息如下：

      root@imx6qsabresd:~# ifconfig eth0
      eth0 Link encap:Ethernet HWaddr 32:34:46:78:9a:dc
      inet addr:192.168.1.4 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::3034:46ff:fe78:9adc/64 Scope:Link
      UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
      RX packets:0 errors:2562 dropped:0 overruns:0 frame:2562
      TX packets:573 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000
      RX bytes:0 (0.0 B) TX bytes:311879 (304.5 KiB)

Re: IMX6Q RMII interface KSZ8895RQXCA

zhangzhencai — Mon, 04 Jun 2018 03:13:06 GMT

你好，最近我们有个项目也在用ksz8895，我们的内核版本和你的是一样的，咨询你几个问题，你们现在怎么样了？能ping通了吗？有没有测试ksz8895的vlan功能？你们有没有用官方的spi驱动？

Re: IMX6Q RMII interface KSZ8895RQXCA

wuweile — Thu, 12 Aug 2021 01:41:41 GMT

我也遇到同样的问题。你的问题解决了吗？怎么解决的

ENET_REF_CLK 对CPU而言是配置成输入还是输出？