[Arm-netbook] next step is a boot image

[Andreas Grapentin]

> On 18. Jan 2023, at 14:54, Luke Kenneth Casson Leighton <lkcl at lkcl.net> wrote:
> 
> On Tuesday, January 17, 2023, Andreas Grapentin <andreas at grapentin.org <mailto:andreas at grapentin.org>>
> wrote:
>> 
>> U-Boot SPL 2013.07-07841-g569c37da7d-dirty (Jan 17 2023 - 19:37:10)
>> Board: EOMA68_A20
>> DRAM: 1024 MiB
>> CPU: 960000000Hz, AXI/AHB/APB: 3/2/2
>> SUNXI SD/MMC: 0
> 
> okaay the SPL loader will now be trying to look on sd/mmc 0
> for a u-boot image.  clearly it is not finding it.

From looking at the sunxi spl code, this is the enumeration of all detected mmc slots, not the configured one. It would be good to compare the output to a known good board.

> which socket is the micro-sd card inserted in?
> (and have you remembered to dd u-boot.bin onto it?)
> and, did you fix the power issues which would allow
> the MD SDcard Level Shifter to activate?

The card is inserted in the socket on the EOMA card, I figured since the micro desktop is not getting power, the slot would probably be unusable.

I started looking at the micro desktop board with my multimeter and did some checks, but it’s difficult without reference to a known good board. But what is maybe noteworthy is that of the three larger capacitors on the board just behind the power socket, both sides of all of them are connected to ground. I assume that part of the board is responsible for the power control? If so, then the small chip in the middle might be blown. Again, hard to verify without a known good board.

>> for reference, this was the previous output:
>> 
>>> U-Boot SPL 2017.01-2 (Jan 18 2017 - 21:30:38)
>>> DRAM: 2048 MiB
>>> CPU: 912000000Hz, AXI/AHB/APB: 3/2/2
>>> Trying to boot from MMC2MMC Device 1 not found
> 
> yup there *is* no SD/MMC 1, u-boot-spl was compiled incorrectly
> in this case.

I think you’re right, let’s discard that previous output as garbage.

> the boot process is complex and multi-stage.
> what the SPL loader is going into is a mere 16k SRAM.

Understood. I’ll keep trying to get u-boot proper up and running.

I’ve noticed that the boot loops above are pretty random — it might be possible I’m not supplying enough power to the microsd slot, I’ll try to use a stronger power supply.

Otherwise, I’m pretty certain I’m using the correct microsd slot, because configuring any other slot in boards.cfg results in timeout errors in the MMC code, which leads to the reported error -1

-A