[U-Boot] [PATCH 1/3] spl: add ymodem support

[Christian Riesch]

Hi,

On Wednesday, March 7, 2012, Mikhail Kshevetskiy <
mikhail.kshevetskiy at gmail.com> wrote:
> On Tue, 6 Mar 2012 22:28:46 +0000
> Laurence Withers <lwithers at guralp.com> wrote:
>
>> On Wed, Mar 07, 2012 at 12:54:05AM +0400, Mikhail Kshevetskiy wrote:
>> > We have an omap l138 based board without jtag and empty spi flash.
>> > UART is an only way to load something on this board, so we are using
>> > uart to load spl image u-boot and then we are using ymodem to load
>> > the rest part of u-boot.
>>
>> Dear Mikhail,
>>
>> I am asking mainly out of curiousity, rather than giving feedback on the
>> patch, but the OMAP-L138 boot ROM has the capability to load both SPL and
>> U-Boot into empty SPI flash using the UART and sfh program or equivalent.
>> (sfh is "serial flash host" for those following along, a program to talk
to
>> the boot ROM over the UART and download some code that the boot ROM can
burn
>> into SPI flash).
>>

It's a combination of boot ROM and a programmer code (sfh) that is
downloaded to the SoC and does the actual lowlevel config of the chip and
the programming to flash. This code must be adapted (and maintained) for
custom boards.

>> What is the advantage in allowing the SPL to flash U-Boot also?
>
> sfh and boot rom does not understand our flash.
>

So there is also another advantage: You can use the same lowlevel
initialization code for downloading code and for normal operation, you will
only need to maintain u-boot for your board.

Christian