[U-Boot] [PATCH v3] Add support for MINI2440 (s3c2440). Documentation about the product can be found on: http://www.friendlyarm.net/products/mini2440

[Marek Vasut]

Dear Ilya Averyanov,

> 2012/4/23 Marek Vasut <marex at denx.de>
> 
> > Dear Ilya Averyanov,
> > 
> > > Dear Marek Vasut,
> > > 
> > > Would you please explain, why do you want to initialize the sdram has
> > 
> > been
> > 
> > > in C code.
> > 
> > Ok, no problem:
> > - You'll be able to call get_ram_size() to scan for ram size as any other
> > board
> > - SDRAM driver will fit properly into the driver model once it's in place
> > (WIP,
> > wanna volunteer for review process?)
> > - It's much cleaner
> > 
> > > If for provide this feature should be written assembly code. And it
> > > would sometimes even harder than the initialization code sdram?
> > 
> > What do you mean?
> 
>  If we use 4kb of SRAM (steppingstone), then at least need to edit
> u-boot/arch/arm/cpu/arm920t/start.S, to add a test from there was a boot
> (NAND or NOR). Edit the address stack. etc ...
> Use the MMU cache for the stack, even a little better, but it is more
> difficult.

Just check where you have SRAM and adjust SP accordingly, it's easy :-)

> 
> > Ah yes, just a remark, please don't top-post. Notice how other people
> > don't do
> > it -- I know gmail does it out-of-the-box, but that doesn't mean it's
> > correct.
> > 
> > Ok.
> > 
> > > 2012/4/21 Marek Vasut <marex at denx.de>
> > > 
> > > > Dear Ilya Averyanov,
> > > > 
> > > > > 2012/4/21 Vasily Khoruzhick <anarsoul at gmail.com>
> > > > > 
> > > > > > 2012/4/21 Ilya Averyanov <averyanovin+uboot at gmail.com>:
> > > > > > > No have problem.
> > > > > > > Available only if you boot from NOR flash.
> > > > > > > If you boot from the NAND 4kb of SRAM (steppingstone) not
> > > > > > > available.
> > > > > > 
> > > > > > For NAND boot it's mapped at 0x0
> > > > > > For NOR boot it's mapped at 0x40000000
> > > > > > 
> > > > > > NAND controller uses it for booting purpose, but anyway for SPL
> > > > > > we should fit code into
> > > > > > 4k (hardware limitation), so I think using assembly here for
> > > > > > SDRAM init is OK.
> > > > > > 
> > > > > > And how will you use the internal SRAM when you boot from NAND,
> > > > > > if the SoC
> > > > > 
> > > > > writes in the SDRAM read data from NAND, and your data will be
> > > > 
> > > > overwritten.
> > > > 
> > > > Why? You'll load SPL into SRAM, then in SPL you'll copy the rest of
> > 
> > uboot
> > 
> > > > from
> > > > NAND to - then already inited - SDRAM and execute it. We even have
> > > > ready-to-use
> > > > NAND SPL.
> > > > 
> > > > > > Regards
> > > > > > Vasily
> > > > 
> > > > Best regards,
> > > > Marek Vasut
> > 
> > Best regards,
> > Marek Vasut

Best regards,
Marek Vasut