&sdc2 {
    non-removable;
    bus-width = <4>;
    mmc-ddr-3_3v;
    /*mmc-hs200-1_8v;*/
    /*mmc-hs400-1_8v;*/
    no-sdio;
    /delete-property/ no-sd;
    no-mmc;
    ctl-spec-caps = <0x8>;
    cap-mmc-highspeed;
    sunxi-signal-vol-sw-without-pmu;
    sunxi-power-save-mode;
    /*sunxi-dis-signal-vol-sw;*/
    max-frequency = <50000000>;
    /*vmmc-supply = <&reg_dcdc1>;*/
    /*emmc io vol 3.3v*/
    /*vqmmc-supply = <&reg_aldo1>;*/
    /*emmc io vol 1.8v*/
    /*vqmmc-supply = <&reg_eldo1>;*/
    status = "okay";
};

2.前往文件夹 brandy/brandy-2.0/u-boot-2018/drivers/sunxi_flash/mmc/sdmmc.c
将return sdmmc_init_for_sprite(0, 0); 修改为return sdmmc_init_for_sprite(0, 2);

3.配置ubifs等等 即可

#kernel command arguments
earlyprintk=sunxi-uart,0x02500000
initcall_debug=0
console=ttyS0,115200
nand_root=ubi0_4
mmc_root=/dev/mmcblk0p4
nor_root=/dev/mtdblock1
init=/init
loglevel=8
coherent_pool=16K
#reserve_list=30M@64M,78M@128M,200M@512M
mac=
wifi_mac=
bt_mac=
specialstr=
root_partition=rootfs
mtd_name=sys
rootfstype=ubifs, rw
#set kernel cmdline if boot.img or recovery.img has no cmdline we will use this
setargs_nor=setenv bootargs  earlyprintk=${earlyprintk} clk_ignore_unused initcall_debug=${initcall_debug} console=${console} loglevel=${loglevel} root=${nor_root} rootwait init=${init} rdinit=${rdinit} partitions=${partitions} cma=${cma} coherent_pool=${coherent_pool} ion_carveout_list=${reserve_list}
setargs_nand=setenv bootargs earlyprintk=${earlyprintk} clk_ignore_unused initcall_debug=${initcall_debug} console=${console} loglevel=${loglevel}  ubi.mtd=${mtd_name} root=${nand_root} rootfstype=${rootfstype} rootwait init=${init} rdinit=${rdinit} partitions=${partitions} cma=${cma} mac_addr=${mac} wifi_mac=${wifi_mac} bt_mac=${bt_mac} selinux=${selinux} specialstr=${specialstr} coherent_pool=${coherent_pool} ion_carveout_list=${reserve_list}
setargs_nand_ubi=setenv bootargs ubi.mtd=${mtd_name} earlyprintk=${earlyprintk} clk_ignore_unused initcall_debug=${initcall_debug} console=${console} loglevel=${loglevel} root=${nand_root} rootfstype=${rootfstype} init=${init} partitions=${partitions} cma=${cma} snum=${snum} mac_addr=${mac} wifi_mac=${wifi_mac} bt_mac=${bt_mac} specialstr=${specialstr} gpt=1
setargs_mmc=setenv  bootargs earlyprintk=${earlyprintk} clk_ignore_unused initcall_debug=${initcall_debug} console=${console} loglevel=${loglevel} root=${mmc_root}  rootwait init=${init} partitions=${partitions} cma=${cma} mac_addr=${mac} wifi_mac=${wifi_mac} bt_mac=${bt_mac} selinux=${selinux} specialstr=${specialstr} coherent_pool=${coherent_pool} ion_carveout_list=${reserve_list}
#nand command syntax: sunxi_flash read address partition_name read_bytes
#0x4007f800 = 0x40080000(kernel entry) - 0x800(boot.img header 2k)
boot_partition=boot
boot_normal=sunxi_flash read 44800000 ${boot_partition};bootm 44800000
boot_recovery=sunxi_flash read 44800000 extend;bootm 44800000
boot_fastboot=fastboot
#recovery key
recovery_key_value_max=0x13
recovery_key_value_min=0x10
#fastboot key
fastboot_key_value_max=0x8
fastboot_key_value_min=0x2

#uboot system env config
bootdelay=1
#default bootcmd, will change at runtime according to key press
bootcmd=run setargs_nand boot_normal#default nand boot
#verify the kernel

verify=N看起来好像也是setargs_nand

Kernel command line:"root=/dev/mmcblk0p4 rootwait init=/init partitions=boot-res@mmcblk0p1:env@mmcblk0p2:boot@mmcblk0p3:rootfs@mmcblk0p4:rootfs_data@mmcblk0p5:UDISK@mmcblk0p6"
Waiting for root device /dev/mmcblk0p4

问题出在上面，bootargs指向的地址还是rootfs根目录还是emmc地址，而你硬件不存在mmcblk0p4，导致一直在等待；需要改成nand对应的文件系统。

你可以在u-boot直接修改bootcmd，将其中的setargs_mmc替换为setargs_nand，sync后重启。如果是SDK里，就修改你选择的板级下的env.cfg文件(不确定具体目录，自己找下，在device目录下)，再进行测试。