I.MX6S imx-ipuv3 freeze during boot

[m_kurmann]

Hello

I am currently trying to port an embbeded Linux from a older i.MX6s to a newer industial model:

(MCIMX6S5EVM10AB to MCIMX6S7CVM08AC)

Kernel version:

Linux arm 3.0.35+ #1 PREEMPT armv7l GNU/Linux

While I do not see any notable difference in the booting process as well as during runtime itself, it sometimes happens (1 out of 5) that the boot process freezes completly during the initalization of the imx-ipuv3 and the only solution is powering it off and on again.

It freezes before the info line:

imx-ipuv3 imx-ipuv3.0: IPU DMFC NORMAL mode: 1(0~1), 5B(4,5), 5F(6,7)

can be printed out.

This behavior can be reproduced independent of the U-Boot or the Hardware used.

Is there an important difference in those two CPU which I completly overlooked ?

Thanks in advance for the help

Michael Kurmann

[igorpadykov]

Hi Michael

there are no differencies which could affect booting, in general one can try to

run ddr test and update image with new ddr calibration settings found from test.

i.MX6/7 DDR Stress Test Tool V3.00 

Note, L3.0.35 is very old kernel and not more supported, recommended to migrate

to new ones described on software web page

i.MX Software | NXP 

Best regards
igor
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[m_kurmann]

Hi Igor

I tried the DDR Stress Test.

While the Test itself does run without problem, the calibration itself does freeze during execution (see the attached file).

Also I am now convinced that the problem resides indeed in the Image Processing Unit or its Driver.

Because the freeze in the Bootprocess only occurs as long as I compile this Driver into the Kernel.

Are there kown settings which can provoke such a behaviour or on the other hand are there default settings which should always work ?

Kind Regards

Michael Kurmann

[igorpadykov]

Hi Michael

>While the Test itself does run without problem, the calibration itself does
>freeze during execution (see the attached file).

this may point that there are issues with board, one can check it using
i.MX6 System Development User’s Guide, check clocks stability, power supplies
ripples

https://www.nxp.com/docs/en/user-guide/IMX6DQ6SDLHDG.pdf

>Also I am now convinced that the problem resides indeed in the Image Processing Unit or its Driver.

>Because the freeze in the Bootprocess only occurs as long as I compile this Driver into the Kernel.

reason may be the same as in ddr test, as adding ipu driver in image can cause more

ddr traffic, more power supply ripples e.t.c.

Best regards
igor

[m_kurmann]

Hi Igor

While we did not found the reason for the freeze, we have found out that the new Bootloader we where using was causing this with our old kernel.

We have switched back to our old bootloader and since then there where no freezes during the bootprocess again.

Looking a bit into the Kernel Code I found that the freeze occurs during the first schedule() call, why and how the bootloader has an effect on this is still a mistery for me.

Anyway you can mark this thread as solved.

Thanks for you help.

Kind Regards

Michael

[m_kurmann]

Hi Igor

Thanks for the quick response I will try the Sress Test Tool.

I am aware that our Kernel is not up to date and the migration to a newer one is one of the top priorities in my bucket list.

Kind Regards

Michael