PROCESSOR-SDK-AM335X: MLO stops when coldbooting, but with a push on reset continues (warmboot )

Thomas Maltesen

This is on a custom hardware using at TPS6217C PMIC. It is a new problem that has arrived in some of the later u-boot/MLO builds.

In a reduced u-boot similar to evm_mini my target stops in MLO after outputting "Trying to boot from MMC1"

Pressing the reset button on the target the device will reboot (now in warmboot) and again output "Trying to boot from MMC1". This time immediatly followed by the U-boot output and my target boots then without problems.

I have not found a fix for this so it is quite a big problem. I have been testing for a long time u-boot and kernel by just pressing reset, so I did not discover this problem.

Does anyone have a clue if there is some configuration that can prevent this?

over 2 years ago

0 Thomas Maltesen over 2 years ago

Intellectual 450 points

For now I have found out that in SPL/MLO the process stops when loading the u-boot image.

The function spl_load_image() is called with device 8 both when the device stops (coldboot) and when the device continues to boot (warmboot).

It seems that the call to the loader (ret = loader->load_image(spl_image, &bootdev)) never returns when coldbooting.

It finds the same loader address in both cases.

0 Judith Mendez over 2 years ago in reply to Thomas Maltesen

TI__Expert 8480 points

Hi,

Please allow a day or so to look at this.

~ Judith

0 Thomas Maltesen over 2 years ago in reply to Thomas Maltesen

Intellectual 450 points

When cold booting the code stops somewhere down in the spl_mmc_do_fs_boot() function, it seems to reach the line calling spl_load_image_ext()

When warmbooting it continues in spl_load_simple_fit().

I have not until now been able to figure out exactly where it stops. I cannot debug the situation because I cannot coldboot with a debugger attached, so I have to add trace output on the console.

0 Judith Mendez over 2 years ago in reply to Thomas Maltesen

TI__Expert 8480 points

Hi Thomas,

Sorry for the delay. E2E has been down for a couple of days.

~ Judith

0 Hong Guan64 over 2 years ago in reply to Judith Mendez

TI__Guru 68290 points

Hi Thomas,
Once u-boot proper is booted, will "reset" cmd @u-boot prompt works on your board?
Best,
-Hong

0 Thomas Maltesen over 2 years ago in reply to Hong Guan64

Intellectual 450 points

I does not reach u-boot when booting fails from coldboot, so in that situation it is not possible to test.

When I press reset and warmboots, I can then stop in u-boot command prompt. And in that case the "reset" command will work and the board reboots fine into kernel.

0 Hong Guan64 over 2 years ago in reply to Thomas Maltesen

TI__Guru 68290 points

Hi Thomas,
The different behavior (coldboot vs warmboot) seems related somehow to the RESET HW design on your board.

Thomas Maltesen said:
I cannot debug the situation because I cannot coldboot with a debugger attached,

Some JTAG debug option for coldboot issue:
- add a "spin" loop in very early SPL code, and rebuild SPL/u-boot
- coldboot your board
- "attach" JTAG to the running board, where "attach" is non-intrusive for the running SPL OR no HW board reset
- break out of the "spin" loop with JTAG
- load SPL code symbol for JTAG debugging on SPL...
I'm attaching AM43xx SPL boot flow, the same flow is applicable for AM335x for your reference...
Best,
-Hong

1513.spl_boot_flow_v1.pdf

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PROCESSOR-SDK-AM335X: MLO stops when coldbooting, but with a push on reset continues (warmboot )