Debugging VoCore2 ROM Startup

[Stefan Roese <sr@denx.de>]

Hi Mauro,

On 15.01.20 11:23, Mauro Condarelli wrote:
>>> I am surprised though as all I could find on differences between
>>> MT7628 and MT7688 are is a reference on Mediatek site:
>>> https://docs.labs.mediatek.com/resource/linkit-smart-7688/en/faq
>>>
>>> Q: What’s MT7628 and how is it different from MT7688AN?
>>>
>>> The MT7628 series are pin-to-pin compatible with the MT7688 series.
>>> However, MT7628 comes with a 2T2R antenna, while MT7688 only supports
>>> 1T1R antenna.
>>>
>>> (Incomplete!) comparison of the two datasheets did not show
>>> relevant differences.
> I have started an analysis of current register status (and I quickly hit
> limitation of the documentation I have):
> 
>      b0000008: 00010000    ....
> E-Fuse Configuration is not pristine, but I don't know what it my mean.
> 
>      b0000010: 00111144    D...
> System Configuration Register 0 ->0000 0000 0001 0001 0001 0001 1000 1000

Not correct:

System Configuration Register 0 ->0000 0000 0001 0001 0001 0001 0100 0100

> 
> 00000000     TEST_CODE
> 000          *
> 100010001    BS_SHADOW
> 000          *
> 1            DBG_JTAG_MODE    1: Normal Boot-up
> 1            TEST_MODE_1         ??
> 0            XTAL_FREQ_SEL    0: 25MHz DIP ???
> 0            EXT_BG           0: BG clock from PMU
> 0            TEST_MODE_0      0: SUTIF
> 100          CHIP_MODE      100: SCAN mode

Not correct. You have here 010, so XTAL with 3-byte ADR

> 0            DRAM_TYPE        0: DDR2
> 
> I am concerned by TEST_MODE_1,XTAL_FREQ_SEL and CHIP_MODE that might
> signal a different up/down pulling of Bootstrapping Pins.
> Could You cross check on LinkIt, please?

=> md b0000000
b0000000: 3637544d 20203832 00100000 00010102    MT7628  ........
b0000010: 00156156 02605500 00000000 00000000    Va...U`.........
b0000020: 10240000 00000000 00000071 0020100c    ..$.....q..... .
b0000030: ffffffc0 04000000 c0030004 00fe00ff    ................
b0000040: 00000000 0001ffff 00000000 00000000    ................
b0000050: 00000000 00000000 00000000 00000810    ................
b0000060: 50050404 05550551 00000000 00000000    ...PQ.U.........

SYSCFG0: 00156156

CHIP_MODE: 011: XTAL with 4-byte ADR.

Mainline U-Boot reports this:

CPU:   MT7628 Rev 1.2 - Boot from XTAL (4-Byte SPI Addr)

and the new code from Weijie reports this:

CPU:   MediaTek MT7688A ver:1 eco:2
Boot:  DDR2, SPI-NOR 4-Byte Addr, CPU clock from XTAL
Clock: CPU: 580MHz, Bus: 193MHz, XTAL: 40MHz

One important difference which might explain a lot, it XTAL_FREQ_SEL
which is 0 in your case and 1 in my case.

IIUTC, then the new code from Weijie takes this XTAL selection
into account. Weijie might comment on this. I suggest that you give
this "u-boot-mtmips.bin" binary a try. Good luck. :)

Thanks,
Stefan