[U-Boot] [PATCH v3 12/15] arm, davinci: Add SPL support for DA850 SoCs

[Christian Riesch]

Hello Heiko,

On Wed, Nov 30, 2011 at 8:41 AM, Heiko Schocher <hs at denx.de> wrote:
> Christian Riesch wrote:
>> On Tue, Nov 29, 2011 at 7:27 PM, Tom Rini <tom.rini at gmail.com> wrote:
>>> On Fri, Nov 25, 2011 at 5:37 AM, Christian Riesch
>>> <christian.riesch at omicron.at> wrote:
>>>> This code adds an SPL for booting from SPI flash on DA850 SoCs.
>>>>
>>>> Signed-off-by: Christian Riesch <christian.riesch at omicron.at>
>>>> Cc: Heiko Schocher <hs at denx.de>
>>>> Cc: Sandeep Paulraj <s-paulraj at ti.com>
>>> Parts of this remind me of omap-common/spl.c so I think longer term we
>>> need to figure out if we can make everyone live with a few more common
>>> SPL files and functions.
>>
>> I stole some ideas from omap-common/spl.c and yes, there are similarities :-)
>>
>>>  Aside, what are the size limitations you're
>>> dealing with here?  Thanks!
>>
>> Size limitation of the SPL? I am using the AM1808 which has 128kB
>> internal SRAM, i think it is the same for all DA8xx SoCs.
>
> If we are using the "nor boot method" in "Legacy NOR Boot" mode
> on the am1808 we must take care, that we can copy only 16kB from
> NOR to the internal SRAM! (But I think, we don't need to take care of
> this mode, as we can use when booting from NOR the "direct NOR Boot"
> mode, where code is exectuted directly from NOR. This mode is used
> on the enbw_cmc board)

I agree, there is a restriction for the "legacy nor boot method", but
if someone can't execute the code directly from NOR with the "direct
NOR boot" for some reason, the "AIS NOR boot" method could be used
[1], which allows copying larger memory areas to the internal SRAM. So
I think there is virtually no restriction from the ROM bootloader.

Regards, Christian

[1] http://www.ti.com/litv/pdf/spraba5b