hi3519av100用emmc启动时找不到emmc

下面是开机代码：[code]System startup

Uncompress Ok!

U-Boot 2016.11 (Jul 09 2019 - 20:56:06 +0800)hi3519av100

Relocation Offset is: 1f712000
Relocating to 3ff12000, new gd at 3fe71ef0, sp at 3fe71ed0
SPI Nor:  Boot Media isn't SPI Nor
NAND:  Check Flash Memory Controller v100 ... Found
SPI Nand ID Table Version 2.7
Cannot found a valid SPI Nand Device
0 MiB
MMC:   
MMC Device 0 not found
*** Warning - No MMC card found, using default environment

In:    serial
Out:   serial
Err:   serial
Net:   gmac0
Error: gmac0 address not set.

Hit any key to stop autoboot:  2  1 [/code]
当我选用spi_nand 启动的时候（默认启动方式），spi nand是可以找到的，当我把启动模式（硬件电阻）修改成emmc启动后，烧写spi nand 的uboot到ddr中时，spi nand的信息就采集不到了。代码如上图所示的一样
[code]SPI Nor:  Boot Media isn't SPI Nor
NAND:  Check Flash Memory Controller v100 ... Found
SPI Nand ID Table Version 2.7
Cannot found a valid SPI Nand Device[/code]
请问我该如何让我从启动（我要验证emmc的功能）。