question about uboot mt7620 RAM_VERSION

[Kang-sen Lu]

Hi, Stefan:

Thanks for your reply.

The uboot in the zbtlink mt7620 router has the signatures follows:

U-Boot 1.1.3 (Nov  9 2016 - 15:34:50)

SoC:MediaTek MT7620
DRAM:  Memory Testing..131072K OK. is 128 MB
relocate_code Pointer at: 87fb0000
enable ephy clock...done. rf reg 29 = 5
SSC disabled.
spi_wait_nsec: 29
spi device id: ef 40 18 0 0 (40180000)
Flash: W25Q128BV

I would like to share my strange experience about RAM version uboot for
mt7620. By pure luck, I found that when I tried to load a newly built uboot
with startup menu option 8, unless I change the filename, say, from
uboot.bin to uboot1.bin, the newly loaded uboot would not startup properly
in RAM.

I don't have the knowledge to find out why this variable "modifies" to be
none-zero is so important to the execution of uboot in RAM. Maybe some
expert in this group can easily figure that out.

Thanks.

Kang-sen

On Tue, Oct 18, 2022 at 7:53 AM Stefan Roese <sr at denx.de> wrote:

> Hi Kang-sen,
>
> (added Weijie Gao to Cc)
>
> On 17.10.22 14:11, Kang-sen Lu wrote:
> >   I am building uboot.bin for mt7620 router.
> >
> > I used start menu option 8, a hidden one choice, to load uboot.bin
> through
> > tftp.
> >
> > The tftp transfer is OK. But when the new uboot starts, it hang.
>
> So which mainline U-Boot build target did you use? Don't you see
> any output on the serial console at all?
>
> > I am wondering if the RAM_VERSION for mt7620 still works.
>
> In mainline U-Boot this is usually handled this way. The SPL U-Boot
> version is responsible for the low-level HW init, like DRAM/DDR init
> etc. It's hard to impossible to chainload this SPL part from a
> running U-Boot version.
>
> The "RAM_VERSION" is usually the main U-Boot proper image "u-boot.bin".
> So in general you are using the correct file here. Even though I have
> not idea, if the build target is correct for your "mt7620 router".
>
> Thanks,
> Stefan
>