uboot- MMC no SDcard

Question

我正在尝试获得一个运行在imx51 Freescale板上的linux内核和linux rootfs。

我编译了linux内核、根文件系统和u-boot，并将镜像复制到SD-card:分区0:引导分区1: rootfs和linux内核

然而，我有以下错误：

U-Boot 2011.12 (Mar 13 2012 - 14:15:41)

CPU:   Freescale i.MX51 family rev3.0 at 800 MHz
Reset cause: POR
Board: MX51EVK
DRAM:  512 MiB
WARNING: Caches not enabled
MMC:   FSL_SDHC: 0, FSL_SDHC: 1
MMC: no card present
MMC init failed
Using default environment

In:    serial
Out:   serial
Err:   serial
Net:   FEC
Warning: failed to set MAC address

Hit any key to stop autoboot:  0 
MX51EVK U-Boot > mmcinfo
MMC: no card present
Device: FSL_SDHC
Manufacturer ID: 0
OEM: 0
Name: Tran Speed: 0
Rd Block Len: 0
MMC version 0.0
High Capacity: No
Capacity: 0 Bytes
Bus Width: 0-bit
MX51EVK U-Boot > mmc init
mmc - MMC sub system

Usage:
mmc read addr blk# cnt
mmc write addr blk# cnt
mmc erase blk# cnt
mmc rescan
mmc part - lists available partition on current mmc device
mmc dev [dev] [part] - show or set current mmc device [partition]
mmc list - lists available devices
MX51EVK U-Boot > mmc list
FSL_SDHC: 0
 FSL_SDHC: 1
MX51EVK U-Boot > mmc dev
MMC: no card present
mmc0(part 0) is current device
MX51EVK U-Boot >

会出什么问题呢？

Answer 1

检查DIP开关，我意识到开关设置为从底部插槽启动SDcard，而我一直从顶部插槽启动。这样，我的问题就解决了。

Answer 2

在file./board/freescale/mx51evk/mx51evk.c

int board_mmc_init(bd_t *bis)
{                                                                  
    u32 index;                                                             
    s32 status = 0;                            
    esdhc_cfg[0].sdhc_clk = mxc_get_clock(MXC_ESDHC_CLK);                      
    esdhc_cfg[1].sdhc_clk = mxc_get_clock(MXC_ESDHC2_CLK);  
}

根据上面的代码片段，我建议检查时钟源。尝试探测MMC0源上的时钟。可能存在时钟源问题。