question about uboot mt7620 RAM_VERSION

[Stefan Roese]

Hi Kang-sen,

On 25.10.22 15:25, Kang-sen Lu wrote:
> Thanks for your reply.
> 
> I cloned the uboot source code from here:
> https://github.com/tessel/uboot-mt7620 
> <https://github.com/tessel/uboot-mt7620>
> 
> I built the uboot.bin for RAM_VERSION. If I select option 8 at power up 
> with the uboot from zbtlink, the new uboot.bin will hang. But if I 
> caused saveenv() to happen, by changing tftp filename artificially, the 
> uboot.bin for RAM_VERSION will start and run properly, by the uboot from 
> zbtlink.

Sorry, this is the ancient U-Boot version. I thought you were talking
about the mainline U-Boot version, which I ported for MT7620/80 some
years ago (with many extensions and fixes by Weijie later on).

I don't remember the details of this ancient MT7620 U-Boot version
and frankly don't want to dig into this (again).

> Maybe Weijie can comment on the experimental result?

Maybe.

> Thanks.
> 
> Kang-sen
> 
> BTW: How does uboot developer usually run the RAM_VERSION uboot.bin, I 
> am curious. Is it loaded with tftp server, or something else?

Yes. This is very handy and frequently done. Load the RAM version
into RAM to the TEXT_BASE address and start it from there via the
"go" command.

BTW: Please keep the ML on Cc. It might be that someone else has
some answers. Or that this topic is interesting for other
people as well.

Thanks,
Stefan

> On Tue, Oct 25, 2022 at 12:46 AM Stefan Roese <sr at denx.de 
> <mailto:sr at denx.de>> wrote:
> 
>     Hi Kang-sen,
> 
>     On 24.10.22 19:58, Kang-sen Lu wrote:
>      > I am wondering if you have read my reply on 10/18. It is very
>     strange to
>      > find that unless I had uboot to do a saveenv, the RAM_VERSION
>     uboot.bin
>      > would not run properly in DRAM.
> 
>     Frankly, I don't really understand this message. It's not clear to
>     me, what you are doing and what is working and what is failing.
> 
>     I thought you were trying to boot the current mainline U-Boot RAM
>     version u-boot.bin. If yes, which build target did you use? What
>     does it show on the serial console?
> 
>     Thanks,
>     Stefan
> 
>      > Thanks.
>      >
>      > Kang-sen
>      >
>      > On Tue, Oct 18, 2022 at 10:05 AM Kang-sen Lu <klu at waav.com
>     <mailto:klu at waav.com>
>      > <mailto:klu at waav.com <mailto:klu at waav.com>>> wrote:
>      >
>      >     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
>     <mailto:sr at denx.de>
>      >     <mailto:sr at denx.de <mailto: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
>      >
> 
>     Viele Grüße,
>     Stefan Roese
> 
>     -- 
>     DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
>     HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
>     Phone: (+49)-8142-66989-51 Fax: (+49)-8142-66989-80 Email:
>     sr at denx.de <mailto:sr at denx.de>
> 

Viele Grüße,
Stefan Roese

-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-51 Fax: (+49)-8142-66989-80 Email: sr at denx.de