linux SD CARD 调试总结

1.先看电路图

image.png

2.再看设备树

&usdhc2 {
    pinctrl-names = "default", "state_100mhz", "state_200mhz";
    pinctrl-0 = <&pinctrl_usdhc2>, <&pinctrl_usdhc2_gpio>;
    pinctrl-1 = <&pinctrl_usdhc2_100mhz>, <&pinctrl_usdhc2_gpio>;
    pinctrl-2 = <&pinctrl_usdhc2_200mhz>, <&pinctrl_usdhc2_gpio>;
    bus-width = <4>; /*位宽配置*/
    cd-gpios = <&gpio4 22  GPIO_ACTIVE_HIGH>;   /*cd 管脚*/
    /*wp-gpios = <&gpio4 21  GPIO_ACTIVE_HIGH>; wp 管脚 */
    /*vmmc-supply = <&reg_usdhc2_vmmc>;    电源控制管脚配置*/
    status = "okay";
};

3. WP 管脚配置不正确或(电路没接)出现如下问题:

3.1 无法存储环境变量

image.png

3.2 无法挂载当前root 分区

image.png
处理办法:先注释掉wp 代码

4.CD 管脚软件配置不正确或者没有配置（硬件没有接）kernel 出现如下log

一直处于要挂载的状态

image.png
处理办法(电路设计就是悬空的):
修改代码：
cd-gpios = <&gpio4 22 GPIO_ACTIVE_LOW>;
为:
cd-gpios = <&gpio4 22 GPIO_ACTIVE_HIGH>;

5.cd管脚硬件没有接uboot 出现如下log

image.png

处理代码如下:

#if !defined(CONFIG_MMC_BROKEN_CD)
    /* we pretend there's no card when init is NULL */
    no_card = mmc_getcd(mmc) == 0;
#else
    no_card = 0;
#endif
#if !CONFIG_IS_ENABLED(DM_MMC)
    no_card = no_card || (mmc->cfg->ops->init == NULL);
#endif
    if (no_card) {
        mmc->has_init = 0;
#if !defined(CONFIG_SPL_BUILD) || defined(CONFIG_SPL_LIBCOMMON_SUPPORT)
        pr_err("MMC: no card present\n");
#endif
        return -ENOMEDIUM;
    }

处理办法: 定义宏 CONFIG_MMC_BROKEN_CD