[U-Boot] [U-boot] mmc write|read howto

[Josh Wu]

On 4/27/2013 5:26 PM, Jagan Teki wrote:
> Hi Josh,
>
> On Sat, Apr 27, 2013 at 11:55 AM, Josh Wu <josh.wu at atmel.com> wrote:
>> Hi, Jagan
>>
>>
>> On 4/27/2013 4:51 AM, Jagan Teki wrote:
>>> Hi All,
>>>
>>> I need some help regarding mmc write and mmc read commands usage.
>>>
>>> I am using a 4GB SD/MMC plus and socked eMMC cards, usually I am
>>> formatting these cards on my host pc with
>>> fat partition and copy the images into card. while in the u-boot level
>>> I am reading the images from card and copy it onto mem addr
>>> like fatload mmc 0 0x1000 uImage.
>>>
>>> Can we write the images onto these cards in u-boot level?, using mmc
>>> write.
>>> same way can we read back using mmc read? if so how to do that.
>>
>> yes, define the CONFIG_FAT_WRITE macro in your board config file.
>> re-build your u-boot. then you will find "fatwrite" command.
>>
>> U-Boot> fatwrite
>> fatwrite - write file into a dos filesystem
>>
>> Usage:
>> fatwrite <interface> <dev[:part]> <addr> <filename> <bytes>
>>      - write file 'filename' from the address 'addr' in RAM
>>        to 'dev' on 'interface'
>>
>> so you can use:
>>   fatwrite mmc 0 0x20000000 file 0x4000
> Thanks for your information.
>
> I will try the fatwrite, and this must require to have the card should
> formatted as FAT on host, is it?

yes.  Also U-Boot can support EXT2, EXT4, UBI read. And EXT4 write 
(CONFIG_CMD_EXT4_WRITE).

> Any possibility to do the formation on u-boot itself.?

according to my understanding, no.

Best Regards,
Josh Wu

>
> Thanks,
> Jagan.
>
>> Best Regards,
>> Josh Wu
>>
>>> Request for help.
>>>
>>> Thanks,
>>> Jagan.
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>>