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[u-boot: v2013.01]

[Author: Bo Shen <[e-mail]>]

mmc命令的帮助信息如下：

U-Boot> mmc

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

当系统启动后，系统会将mci0设置为当前设备。使用mmcinfo就可以看到插入到mmc controller 0的sdcard信息。

U-Boot> mmcinfo

Device: mci

Manufacturer ID: 3

OEM: 5344

Name: SD04G

Tran Speed: 25000000

Rd Block Len: 512

SD version 2.0

High Capacity: Yes

Capacity: 3.8 GiB

Bus Width: 4-bit

如果SoC支持多个mmc controller并且使能，使用mmc list来查看使能了几个， 可以通过mmc dev来查看当前是那个设备，或者通过mmc dev <NO.>来切换。

像我的系统支持两个mmc controller.

U-Boot> mmc list (显示有几个mmc controller)

mci 0

mci 1

U-Boot> mmc dev (显示当前是那个device)

mmc1 is current device

U-Boot> mmc dev 0 (设置0为当前设备)

mmc0 is current device

如果，换sdcard，则使用mmc rescan来重新获取sdcard信息

U-Boot> mmc rescan (重新scan当前设备)

mci: setting clock 257812 Hz, block size 512

mci: setting clock 22000000 Hz, block size 512

mci: setting clock 257812 Hz, block size 512

gen_atmel_mci: CMDR 00001048 ( 8) ARGR 000001aa (SR: 0c100025) Command Failed

mci: setting clock 257812 Hz, block size 512

mci: setting clock 22000000 Hz, block size 512

U-Boot> mmcinfo (列出当前设备的信息)

Device: mci

Manufacturer ID: 1

OEM: 5041

Name: SK512

Tran Speed: 25000000

Rd Block Len: 512

SD version 1.10

High Capacity: No

Capacity: 472.5 MiB

Bus Width: 4-bit