[U-Boot] [PATCH] arm: at91sam9n12: change EBI IO to high drive mode

[Bo Shen]

Hi Albert,

On 07/17/2013 06:10 PM, Albert ARIBAUD wrote:
> Hi Bo,
>
> On Wed, 17 Jul 2013 17:14:17 +0800, Bo Shen <voice.shen at atmel.com>
> wrote:
>
>> As both the DDR SDRAM and NAND flash connect to EBI on at91sam9n12
>> and share the lower 8 bits data line. If use low drive of the data
>> line, it will cause DDR data access corrupt in lower address, so
>> change the data line to high drive mode
>>
>> This will fix the Linux kernel boot issue when use Lower address
>
> Wait--does this mean that there is no separate chip selects for NAND and
> DDR on this SoC?

No. The NAND and DDR has there own chip selects.

This is chip specific. If DDR and NAND share data line, if we use low 
drive for EBI IO, it will cause DDR low memory address content corrupt. 
For example, if the DDR base address is 0x20000000, if we use 0x20008000 
as entry address of Linux kernel, then it won't boot up successfully. 
So, if we need to use low memory address, we need this to fix.

> Amicalement,
>

Best Regards,
Bo Shen